Language：English   Publishing type：Research paper (scientific journal)  

The primary coordination sphere of the multinuclear cofactor (Mn4CaOx) in the oxygen-evolving complex (OEC) of photosystem II is absolutely conserved to maintain its structure and function. Recent time-resolved serial femtosecond crystallography identified large reorganization of the primary coordination sphere in the S2 to S3 transition, which elicits a cascade of events involving Mn oxidation and water molecule binding to a putative catalytic Mn site. We examined how the crystallographic fields, created by transient conformational states of the OEC at various time points, affect the thermodynamics of various isomers of the Mn cluster using DFT calculations, with an aim of comprehending the functional roles of the flexible primary coordination sphere in the S2 to S3 transition and in the recovery of the S2 state. The results show that the relative movements of surrounding residues change the size and shape of the cavity of the cluster and thereby affect the thermodynamics of various catalytic intermediates as well as the ability to capture a new water molecule at a coordinatively unsaturated site. The implication of these findings is that the protein dynamics may serve to gate the catalytic reaction efficiently by controlling the sequence of Mn oxidation/reduction and water binding/release. This interpretation is consistent with EPR experiments; g ∼ 5 and g ∼ 3 signals obtained after near-infrared (NIR) excitation of the S3 state at 4 K and a g ∼ 5 only signal produced after prolonged incubation of the S3 state at 77 K can be best explained as originating from water-bound S2 clusters (Stotal = 7/2) under a S3 ligand field, i.e., the immediate one-electron reduction products of the oxyl-oxo (Stotal = 6) and hydroxo-oxo (Stotal = 3) species in the S3 state.

DOI： 10.1021/acs.jpcb.2c02596

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Publishing type：Research paper (scientific journal)   Publisher：{MDPI} {AG}  

DOI： 10.3390/molecules27072098

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Three tetrahedral cobalt(II) complexes [CoX2(H2thp)2] were prepared and characterized (H(2)thp = 2-(1,4,5,6tetrahydropyrimidin-2-yl)phenol, X = Cl, Br, and I). X-ray crystallographic analysis indicates that the H2thp ligand coordinates to a Co ion in monodentate fashion in zwitterionic form. In the crystal, all the complexes formed characteristic one-dimensional chain structures via N-H center dot center dot center dot X hydrogen-bonding interactions. The static magnetic measurements showed that the g-factors and axial zero-field splitting parameters for Br- and I- derivatives are quite similar despite the deference in the halide ligand. A significant frequency dependence was observed for all the complexes in dynamic magnetic measurements in the presence of an external field. The relaxation dynamics below 3 K for the Br- and I- derivatives were found to be dominated by Raman relaxation process, while that of the Cl- derivative was dominated by Orbach process. The relatively long intermolecular Co center dot center dot center dot Co distances > 8 angstrom resulted in no influence in the static magnetic properties and the QTM phenomena.

DOI： 10.1016/j.ica.2021.120667

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Molecular and crystal structures of the mononuclear cobalt(III) complexes bearing N'-(pyridin-2-ylmethylene) picolinoylhydrazidate (Lpy-), [Co(Lpy)3] (1) and [Co(Lpy)2]BF4 (2a and 2b), as well as those of the Lpy-bridged CoIII2CoII trinuclear and CoII4 tetranuclear complexes, [Co3(Lpy)4(H2O)2](BF4)4 (3) and [Co4(Lpy)4Cl2(CH3CN)2] (BF4)2 (4), were determined by the single-crystal X-ray diffraction method, which revealed a variety of coordination and bridging modes of the multidentate Lpy- ligand. The protonated free hydrazone, HLpy, exists as an E-form (in regard to the imine configuration) in the solid state and in solution. In the mononuclear CoIII complexes, the hydrazonate anion (Lpy-) coordinates to a CoIII center in three different coordination modes: a bidentate kappa 2N1,N2 mode with the E-form (in 1) and two kinds of tridentate modes with the respective configuration, Z-kappa 3N1,N2,N4 and E-kappa 3O,N3,N4, in 2a and 2b. The former tridentate mode was sterically favored in the CoIII complexes, resulting in the five- and six-membered chelate rings, with a conversion of the imine configuration during the complexation. Complex 2a could also serve as a complex ligand toward a CoII ion with the kappa 2O, N3 mode, forming the CoIII-CoII-CoIII trinuclear complex (3). In the novel tetranuclear CoII complex (4), the ELpy- hydrazonates bridged two CoII ions in two different modes: mu-kappa 2O,N1:kappa 3O,N3,N4 and mu-kappa 2N1,N2:kappa 3O,N3,N4, where all chelate coordinations formed a five-membered ring with the CoII ion.

DOI： 10.1016/j.ica.2021.120464

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Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography ({IUCr})  

DOI： 10.1107/S2056989020016096

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jphotochem.2020.112905

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The correlation between magnetic relaxation dynamics and the alignment of single-ion magnets (SIMs) in a crystal was investigated using four analogous cobalt(ii) complexes with unique hydrogen-bond networks. The hydrogen-bonding interactions in the crystals resulted in a relatively short intermolecular CoMIDLINE HORIZONTAL ELLIPSISCo distance, which led to non-zero intermolecular magnetic coupling. All the complexes with a CoMIDLINE HORIZONTAL ELLIPSISCo distance shorter than 6.5 angstrom exhibited zero-field slow magnetic relaxation as weak magnetic interactions split the ground +/- M-s levels and suppressed quantum tunneling of magnetization (QTM). In particular, antiferromagnetically coupled one-dimensional chain SIM networks effectively suppressed QTM when the two intrachain CoMIDLINE HORIZONTAL ELLIPSISCo distances were non-equivalent. However, when the two distances in a chain were equivalent and each molecular symmetry axis aligned parallell within the chain, QTM suppression was insufficient because magnetic coupling from the adjacent molecules was virtually cancelled. Partial substitution of the Co-II ion with the diamagnetic Zn-II ion up to 33% for this complex resulted in complete QTM suppression in the absence of an external field. These results show that the manipulation of intermolecular distances and alignments is effective for suppressing undesired QTM events in SIMs.

DOI： 10.1039/d0ra08286d

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography ({IUCr})  

DOI： 10.1107/S2056989020014437

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

Several series of platinum(II), palladium(II), and nickel(II) complexes bearing 8-(diphenylphosphino)quinoline (PQ(H)) or its 2-methyl or 2-phenyl derivatives (PQ(Me) or PQ(Ph)) were synthesized, and their crystal structures and behaviors in solution were investigated. Most of the complexes [M(PQ(R))(2)]X-2 (M-II = P-II, Pd-II, or Ni-II; R = H, Me or Ph; X = monoanionic ions) characterized in this study have an approximately square-planar coordination geometry with two bidentate P,N-chelating or monodentate P-donating quinolylphosphine ligands in the cis(P,P) configuration. A large steric requirement from the Me or Ph substituent introduced at the 2-position of the quinoline ring gives the resulting complexes severe distortion. The Pt-II and Pd-II complex cations maintained the square-planar coordination geometry, but the M(II )center was displaced from the chelating ligand plane. This bending of the chelate coordination makes the M-N(quinoline) bond weaker, as demonstrated by the longer M-N bonds. In accord with the bond weakening, the partial dissociation of the PQ(H) or PQ(Me) chelates by substitution with halide anions were observed using UV-vis spectroscopy and X-ray crystallography. In contrast, the PQ(Ph) complexes were stable in solution toward the addition of halide anions; the intramolecular pi-pi stacking interaction between the coordinating quinolyl and the 2-substituted phenyl rings protects the M-II center from nucleophilic attack. In the corresponding Ni-II complexes, the steric congestion arising from the mutually cispositioned PQ(R) ligands resulted in a larre tetrahedral distortion around the Ni-II center. However, the intramolecular pi-pi stacking interaction was still effective in the PQ(Ph) complex, and this interaction can explain some unusual robustness and electrochemical properties of the Ni-II-PQ(Ph) complex.

DOI： 10.1021/acs.inorgchem.0c02706

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

DOI： 10.1039/D0QI00919A

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ica.2020.119862

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.poly.2020.114401

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Two new tetranuclear iron(II) complexes, [Fe-4(H2LH)(6)](ClO4)(8) (1ClO(4): H2LH = N,N'-bis(imidazole-4-ylmethylidene)-1.4-diaminobenzene) and [Fe-4(H2LMe)(6)](BF4)(8) (2BF(4): H2LMe = N,N'-bis(5-methylimidazole-4-ylmethylidene)-1.4-diaminobenzene), were synthesized from Fe(ClO4 or BF4)(2)center dot 6H(2)O, 1.4-diaminobenzene and 4-formylimidazole or 5-methyl-4-formylimidazole. X-ray analysis revealed that these complexes have a tetrahedral structure with four iron(II) ions at the apexes and the bridging bis(bidentate) ligands on the edges. The internal space of the tetrahedron was filled with the phenylene segments of the bridging ligands. Magnetic susceptibility studies indicated that both 1ClO(4) and 2BF(4) showed gradual but incomplete spin-crossover (SCO) behavior, because the densely packed tetrahedral structure could prevent the contraction of the Fe-N bonds on the highspin to low-spin transition.

DOI： 10.1016/j.ica.2019.119373

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Dinuclear complex, [Fe-2(H2L1'(Me))(3)](ClO4)(4) (1Me, H(2)L1,(Me) = N,N'-(1,3 -phenylene)bis (1 -(5 -methyl-1H-imidazol-4-yl)methanimine)), and octanuclear complexes, [Fe-8(H2L2,H)(12)](ClO4)(16 )(2HClO: H2L2,H = N,N'-(1,3-phenylenebis(methylene))bis-(1-(1H-imidazol-4-yl)methanimine) and [Fe-2(H2L2'(Me))(12)](X)(16) (2MeX: H2L2,Me = N.N'-(1,3 -phenylene))bis-(methylene))bis- (1-(5-methyl-1H-imidazol-4-yl)methanimine), X = ClO4, BF4), were synthesized. It was revealed by X-ray analysis that 1Me has a dinuclear mesocate structure. On the other hand, 2HClO4 and 2MeX have novel octanuclear bicapped trigonal prism structures with six iron(II) sites having the meridional configuration on vertexes and two iron(II) sites having the facial one on the centers of each triangular base. Magnetic susceptibility studies indicated that these dinuclear and octanuclear complexes show gradual spin-crossover (SCO) behavior.

DOI： 10.1246/bcsj.20190360

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

Crystal structures and crystallisation behaviours of a series of first-row transition-metal(II) complexes bearing 1,1,1-tris[2-aza-3-(imidazol-4-yl)prop-2-enyl]ethane (H3L), [M-II(H3L)]Cl(ClO4) (M = Mn, Fe, Co, Ni and Zn) were examined. These compounds crystallise in an orthorhombic crystal system with a non-enantiogenic (Sohncke) space group P2(1)2(1)2(1), resulting in spontaneous resolution of the chiral complex cations. Hydrogen bonds between the imidazole N-H atoms in the tripodal ligand and chloride anions give enantiomorphic crystals with a homochiral three-dimensional network structure. In order to verify the spontaneous resolution of these compounds, solid-state circular dichroism spectra of the resulting single crystals were measured (KBr disk method). Unexpectedly, the observed spectra indicated that imbalanced formation of the enantiomorphic crystals (i.e., left-handed Lambda-form vs. right-handed Delta-form complex cations) in all cases. Moreover, in the cases of Ni-II and Zn-II compounds, predominant enantiomorphic crystals formed by spontaneous resolution were always the same (in at least ten of our recrystallisation experiments). These observations suggest that there is a certain (but as yet unknown) factor that affects the predominant deposition of either enantiomorphic crystal when spontaneous resolution takes place from a solution of a racemic mixture in which rapid racemisation occurs.

DOI： 10.1039/c9ce01864f

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

(E)-N-Benzylidenepicolinohydrazide (Hbphz) was used to synthesize a series of hydrazonato-bridged homodinuclear Ln(2)(III) dithiocarbamato (RR'dtc(-)) complexes of the form [{Ln(RR' dtc)(2)}(2)(mu-bphz)(2)] {Ln= La, Pr, Nd, Sm or Eu; RR'= dimethyl-(Me-2) or pyrrolidine-(pyr)}. X-ray crystallographic studies revealed that these complexes possessed a common head-to-tail type dinuclear structural motif in which two hydrazonato ligands bridged two Ln(III) centers in the mu- 1 kappa N-2(py),O:2 kappa O-2,N(imine) mode and two RR'dtc ligands coordinated to each Ln(III) center. Interestingly, while the Sm-III and Eu-III complexes crystallized as simple 8:8-coordinate dinuclear molecules, the lighter Ln(III) (i.e. La-III, Pr-III and Nd-III) complexes afforded in some cases 9:9-coordinate molecules, where the ninth coordination site was occupied by a solvent ethanol or methanol molecule. Even for the lighter Ln(III) complexes, the complexes were solved in dichloromethane or chloroform as the 8:8-coordinate dimer, as revealed by H-1 NMR spectroscopy. In the UV-visible absorption and magnetic circular dichroism (MCD) spectra of the complexes, similar spectral patterns for ligand-centered and Laporte forbidden f-f transitions were observed. The MCD spectral studies demonstrated the characteristic magneto-optical behavior of the complexes.

DOI： 10.1016/j.ica.2019.119124

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

Four new homodinuclear lanthanoid(III) dithiocarbamato (RR'dtc(-)) complexes bridged by 2,2'-bipyrimidine (bpm) of the form [{Ln(RR'dtc)(3)}(2)(mu-bpm)] {Ln = Nd or Eu; RR' = dimethyl- (Me-2) or pyrrolidine(pyr)} were prepared and their crystal structures and spectroscopic properties were characterized. The crystallographic studies revealed that all of the complexes possess a similar structural motif with an 8:8-coordination geometry, in which the bpm ligand bridges two Ln(III) centers in the kappa N-2(1,1') : kappa N-2(3,3') mode and three RR'dtc(-) ligands coordinate to each Ln(III) center. The complexes exhibit weak but relatively sharp f-f transition bands in the absorption and magnetic circular dichroism (MCD) spectra recorded in the visible region. The MCD spectral studies demonstrated the magneto-optical behavior of the complexes. The spectral features of the dithiocarbamato complexes were distinctly different from those of their beta-diketonato analogues, suggesting the coordination environment around the Ln(III) center influences the electronic structure and spectroscopic symmetry of the complexes in solution. (C) 2019 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2019.07.046

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

Complexation properties of U-shaped ligands, L-1 and L-2, which are Schiff bases of 5,5 '-(9,9-dimethylxanthene-4,5-diyl)bis(salicylaldehyde) (H(2)xansal) with 3-amino-1-propanol or 2-hydroxybenzylamine, respectively, were investigated to construct polynuclear manganese complexes. In these ligands, two O,N,O-Schiff bases are bridged by a xanthene backbone. The reactions of H4L1 or H4L2 with manganese salts afforded tetra- and dinuclear manganese complexes, including the tetramanganese(ii,ii,iii,iii) complex [Mn-4(L-1)(2)(mu-OAc)(2)] with a Mn4O6 core exhibiting an incomplete double-cubane structure. In the Mn4O6 core, phenolate and alkoxide O atoms bridge the manganese ions. Deprotonated 3-hydroxypropyl groups were crucial to the assembly of four manganese ions because the phenolate-bridged dimanganese(iii,iii) complex [Mn-2(H2L1)(2)](2+) was obtained in the absence of a base, and H4L2, which has 2-hydroxybenzyl groups instead of 3-hydroxypropyl groups in H4L1, afforded the cyclic dimanganese(iv,iv) complex [Mn-2(L-2)(2)]. We disclosed that [Mn-4(L-1)(2)(mu-OAc)(2)] was converted to the oxo-bridged tetramanganese(iii,iii,iii,iii) complex [Mn-4(L-1)(HL1)(mu(3)-O)(mu-OAc)(2)](+) by treating with NH4PF6 or NH4BF4: a triply bridging alkoxide was protonated and replaced by an oxide ligand. The cyclic voltammograms of [Mn-4(L-1)(HL1)(mu(3)-O)(mu-OAc)(2)](+) suggested that the reverse reaction forming [Mn-4(L-1)(2)(mu-OAc)(2)] occurred in the electrochemical processes and was assisted by protonation.

DOI： 10.1039/c9dt03007g

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Photosynthetic water oxidation is catalyzed by a Mn4CaO5-cluster in photosystem II through an S-state cycle. Understanding the roles of heterogeneity in each S-state, as identified recently by the EPR spectroscopy, is very important to gain a complete description of the catalytic mechanism. We performed herein hybrid DFT calculations within the broken-symmetry formalism and associated analyses of Heisenberg spin models to study the electronic and spin structures of various isomeric structural motifs (hydroxo-oxo, oxyl-oxo, peroxo, and superoxo species) in the S3 state. Our extensive study reveals several factors that affect the spin ground state: (1) (formal) Mn oxidation state; (2) metal-ligand covalency; (3) coordination geometry; and (4) structural change of the Mn cluster induced by alternations in Mn···Mn distances. Some combination of these effects could selectively stabilize/destabilize some spin states. We found that the high spin state ( Stotal = 6) of the oxyl-oxo species can be causative for catalytic function, which manifests through mixing of the metal-ligand character in magnetic orbitals at relatively short O5···O6 distances (<2.0 Å) and long MnA···O5 distances (>2.0 Å). These results will serve as a basis to conceptually identify and rationalize the physicochemical synergisms that can be evoked by the unique "distorted chair" topology of the cluster through cooperative Jahn-Teller effects on multimetallic centers.

DOI： 10.1021/acs.jctc.8b01055

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A series of Nd-III and Eu-III complexes containing achiral or chiral dithiocarbamato (dtc) ligands, [Ln(Xdtc)(3)(NN)] {Ln = Nd or Eu; X = dimethyl- (Me-2), pyrrolidine- (pyr), or (S)-prolinol- (S-proOH); NN = 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy)}, were prepared and their crystal structures and spectroscopic properties, in particular the natural circular dichroism (CD) and magnetic circular dichroism (MCD), were investigated. The crystal structures of the complexes analyzed by the X-ray diffraction method showed an 8-coordinate geometry around the Ln III center with comparable structural parameters to one another and to the related complexes reported previously. These complexes exhibited similar spectral patterns in their absorption, natural CD and MCD spectra in solution. Weak but characteristic sharp f-f transition bands were observed in the absorption and MCD spectra, but no CD signals associated with these transitions were observed even in the S-proOHdtc complexes. The MCD spectral pattern of the Eu-III complexes revealed a local C-2v symmetry around the Ln(III) center in solution, in contrast to the aqua and the analogous beta-diketonato Eu-III complexes.

DOI： 10.1016/j.ica.2018.09.064

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography ({IUCr})  

DOI： 10.1107/S2414314618014827

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley-VCH Verlag  

Reactions of methyl (S)-2-[(2-hydroxybenzylidene)amino]-3-(1H-imidazol-4-yl)propanoate (S-H2LMe) and various transition-metal(II) salts (MX2: M = Mn, Fe, Co, and Ni
X = ClO4, Cl, OAc, etc.) are examined. During the reactions with MnII and CoII salts, the MII ion is oxidized by air to form a cationic complex with two mono-deprotonated ligands, [MIII(S-HLMe)2]X [M, X = Mn, ClO4 (S-1ClO4)
Co, ClO4 (S-3ClO4)
and Co, Cl (S-3Cl)], where (S-HLMe)– is coordinated to a MIII center in a tridentate κ3O,N,N′ mode with a mer configuration. In contrast, the NiII ion is not oxidized
only one of the ligands is deprotonated to form a similar monocationic complex, [NiII(S-HLMe)(S-H2LMe)]PF6 (S-6PF6), which forms a dimer structure by double hydrogen bonds between the coordinating phenoxide and phenol groups in the crystal. Interestingly, the above complexes show slow racemization of the ligand, as confirmed by circular dichroism spectroscopy. Racemic NiII complexes of [Ni(HLMe)(H2LMe)](PF6 or Cl) (rac-6PF6 or rac-6Cl) are isolated and their crystal structures are confirmed by X-ray diffraction analysis. In the case where Co(OAc)2 is used as the metal(II) salt, a new ligand dimerization reaction takes place to afford a complex of [Co(H2LLMe)]Cl (7Cl, H4LLMe = methyl (E)-3-{[3-(1H-imidazol-4-yl)-1-methoxy-1-oxopropano-2-yl]amino}-2-[(1H-imidazol-4-yl)methyl]-2-[(2-hydroxybenzylidene)amino]-3-(2-hydroxyphenyl)propanoate).

DOI： 10.1002/ejic.201800137

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Chemical Society of Japan  

Two geometric isomers of [RuCl2(PPh3)2(O-N)]-type complex were prepared and characterized by X-ray crystallography (PPh3 = triphenylphosphine, O-N = Hpia/pia-, Hpia = 3-hydroxypicolinamide). The electrochemical properties of the complexes upon protonation/deprotonation were investigated. The redox potential of the Ru center was remarkably shifted by isomerization. The UV-vis and electrochemical measurements suggested that slow isomerization from trans(P,Cl),trans(P,N) geometry to trans(P,P) geometry induced the oxidation and deprotonation of the complex.

DOI： 10.1246/cl.171166

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c8cc04756a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

Three tetracoordinated cobalt(ii) complexes with a series of unsymmetrical bidentate ligands were synthesized and crystallographically characterized. Although their static magnetic properties are similar, their dynamic magnetic properties differ drastically depending indirectly on intermolecular hydrogen-bonding interactions.

DOI： 10.1039/C8DT04537B

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

This paper describes the development of a simple magnetic circular dichroism (MCD) apparatus from a wood base and neodymium magnets and its configuration in the Faraday alignment. The applicability and effectiveness of the apparatus for MCD spectra measurements have been examined. The apparatus was used by undergraduate students to conduct MCD experiments on Ni2+, Nd3+, and Eu3+ ions in aqueous solutions. Absorption spectra of the sample solutions were also measured. The results of the MCD and absorption spectra of d-d and f-f transition were compared. The results indicate that the apparatus can be used to teach undergraduate students.

DOI： 10.1021/acs.jchemed.7b00106

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Cobalt(III) complexes with three unsymmetrical bidentate ligands containing a noncoordinating N-H bond and a phenolate-O donor as hydrogen-bond donor and acceptor, respectively, were prepared and characterized. H-1 NMR spectroscopy indicated that all the tris-chelate Co(III) complexes prepared favor the mer configuration in solution. [Co(Hthp)(3)] and [Co(Himn)(3)] also possess the mer configuration in the crystals (Hthp(-) = 2-(1,4,5,6-tetrahydropyrimidin-2-yl)phenolate, Himn(-) = 2-(2-imidazolinyl)-phenolate). On the other hand, [Co(Himl(-))(3)] takes the fac configuration in the crystal (Himl(-) = 2-(2-irnidazolyl)-phenolate). 'these Co(III) complexes showed three types of characteristic supramolecular structures: ladder, distorted hexagonal sheet, and honeycomb sheet structure; constructed by intermolecular hydrogen bonds. Heating [Co(Himn)(3)] and [Co(Himl)(3)] in methanol selectively afforded precipitates of the fac isomer due to the low solubility of the hydrogen-bonded supramolecular structures. This mer to fac isomerization upon crystallization in methanol is presumably induced by the formation of highly ordered hydrogen-bond networks via the methanol molecule. The fac isomers remained intact in dimethyl sulfoxide (DMSO) for longer than a week at room temperature. Upon heating, however, fac to mer geometrical isomerization of both fac-[Co(Himn)(3)] and fac-[Co(Himl)(3)] was observed in DMSO. Thus, mer/fac interconversion was achieved by heating in two different solvents, due to the forrnation of a supramolecular assembly of hydrogen-bond networks.

DOI： 10.1021/acs.cgd.6601438

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIOMED CENTRAL LTD  

Background: Light calcareous stone materials used in connection with cultural heritage objects, such as pedestals, or used as wall facings in connection with bronze statues or joints often show green staining due to the corrosion products from the bronze elements. The green stains alter the appearance of the monument and thus disrupt the original intention. Due to this, several cleaning methods, often involving ammonia, have been developed for removal of copper stains from stone surfaces. This paper describes a new, highly efficient method for cleaning copper stains from calcareous stone by introducing the chelating agent ethylenediamine in a poultice consisting of Laponite (R) RD, Arbocel (R) BC1000 and CMC.
Results: Cleaning experiments were performed on marble and on a calcareous sandstone plinth contaminated with natural copper corrosion products due to outdoor exposure of an untreated bronze statue. The cleaning results were evaluated by visual observations.
Conclusion: The chemical cleaning of copper stained calcareous stone surfaces has been investigated and a new method for removal of copper stains has been developed. A solution of 0.1 M ethylenediamine in a poultice consisting of Laponite (R) RD/Arbocel (R) BC1000/CMC has shown to be an effective, economical, and fast do-it-yourself method.

DOI： 10.1186/s40494-016-0102-5

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Reactions of [(Cp*Rh)(2)(mu-OH)(3)]OH (Cp*=eta(5)-C5Me5-) and thymine (=H(2)thym) in methanol in the presence or absence of a certain metal salt were examined. From the reaction mixture without any template metal salt, a dinuclear hydroxido-bridged complex bearing monodentate monodeprotonated thyminato ligands,1[Cp*Rh(Hthym-kappa N-1))(2)(mu-OH)(2)], was isolated after recrystallization from water. In the presence of a metal salt MXn{=NaPF6, NaBF4, NaNO3, Ca(NO3)(2), Ca(ClO4)(2), La(NO3)(3), Eu(NO3)(3), Dy(NO3)(3) and Er (NO3)(3)) were deposited orange crystals (1P, 1B, 1N, 2N, 2C, 3N, 4N, 5N and 6N, respectively) which consist of a thyminato(2-)-bridged tetranuclear Cp*Rh complex incorporating a Mn+ cation, [(Cp*Rh)(4)(mu-thym)(4)M](n+). All complexes were characterized by the single-crystal X-ray diffraction method, which revealed that homochiral aggregations of four Rh-III centers were achieved to give metallacalix[4]arene-type clusters. It was also observed that the bridging modes of thyme(2-) ligands were dependent on the template metal ion. In the Na+-incorporated clusters (1X, X = P, B or N) a thyme(2-) ligand bridged two Rh-III and the third Na+ ions with a mu(3)-1 kappa N-1:2 kappa N-2(3),O-2:3 kappa O-2 mode, while in the Ln(3+) analogs (Ln = La, Eu, Dy or Er: 3N-6N) thyme(2-) exhibited a different bridging mode, mu(3)-1 kappa N-1:2 kappa N-2(3),O-4:3 kappa O-2. In the cases of Ca2+-incorporated clusters, the bridging mode is further dependent on the associated anion; only the mu(3)-1 kappa N-1:2 kappa N-2(3),O-2:3 kappa O-2-type cluster was obtained in the NO3- salt (2N), but the ClO4- salt (2C) afforded both types of the bridging clusters piled up alternatively in the crystals. The tetranuclear structures with a template metal cation, [(Cp*Rh)(4)(mu-thym)(4)M](n+), are maintained in solution. The magnetic behaviors of the Dy3+- and Er3+-incorporated complexes (5N and 6N) are also reported. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2016.01.023

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Complexation of 2-hydroxy-N-(n-aminoalkyl)benzamides, where n-aminoalkyl substituents are 2-amino-2-methylpropyl (H(2)L2(Me2)), (R)-2-aminopropyl {(R)-H(2)L2(Me)} and 3-aminopropyl (H(2)L3), with manganese(II)chloride or perchlorate were examined. With the 2-aminopropyl derivatives, dinuclear methoxido-bridged manganese(III) complexes bearing the dianionic ligands, [{Mn(L2(Me2) or (R)-L2(Me)) (MeOH)}(2)(mu-OMe)(2)] (2 or 4), were isolated and their crystal structures were determined. There was a weak antiferromagnetic interaction between two axially distorted Mn-III centers in 2. Also, with the ligand of (L2(Me2))(2) a mononuclear manganese(IV)complex, [Mn(L2(Me2))(2)]center dot DMF (3 center dot DMF) was obtained. In the crystal of 3 center dot DMF a heterochiral dimerization via the intermolecular double hydrogen-bonds was observed. In the case of reactions with H(2)L3, mononuclear manganese(III)complexes, [Mn(H(2)L3 ')(2)Cl-2] Cl (6)and [Mn(H(2)L3 ')(2)(MeOH)(2)]Cl-2(ClO4)(7), were afforded, where the ligand (H(2)L3 ')has a phenolateamide-ammonium type zwitterionic form of H(2)L3 and coordinates to a Mn-III center via the phenolato-O and amide-O atoms to form a six-membered chelate ring. Furthermore, a tetranuclear (Mn2Mn2III)-Mn-II double incomplete-cubane type cluster compound, [Mn-4(HL3)(2)Cl-2(OMe)(6)(MeOH)(2)]center dot 4MeOH (5a center dot 4MeOH) was revealed by the single-crystal X-ray diffraction study, although the bulk crystals (5)obtained from the reaction mixture showed a different PXRD pattern. The elemental analysis of the bulk crystals of 5 suggested that they consist of the same tetranuclear clusters. It is interesting that the bulk crystals of 5 were highly efflorescent, and it was suggested that their coordinated MeO and MeOH ligands were easily substituted by OH and H2O, respectively, in atmospheric air. This conversion changed their magnetic behaviors drastically. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2016.03.036

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIOMED CENTRAL LTD  

Background: Calcareous materials, like marble used in connection with cultural heritage objects such as statues and pedestals, or as wall facings on buildings, often show a brownish staining owing to contact with iron metal or iron-containing minerals in the stone. The discolouration alters the appearance of the stone, which is undesirable from an aesthetic point of view. Despite rust staining being a conspicuous phenomenon and numerous works that have dealt with the problem of removing rust stains, a simple and non-toxic method has so far been missing. This paper describes a highly efficient method for cleaning rust stains from marble by introducing the chelating amino acid cysteine in a Laponite poultice in combination with the strong reducing agent sodium dithionite.
Results: Cleaning experiments were performed on artificially discoloured samples of various types of Carrara Bianco marble and on naturally rust stained marble. To begin with, solutions of cysteine in combination with sodium dithionite and ammonium carbonate were tested by immersion of samples into the different solutions. Secondly, solutions of cysteine and sodium dithionite with and without buffering were used in a poultice consisting of Laponite (R) RD, Arbocel (R) BC1000 and CMC. The poultice was applied on three different marble types: Carrara Fabricotti, Carrara Vagli and Carrara La Piana. Thirdly, the optimized method was tested on original rust stained material of Greenlandic marble, which has been used as wall facing, and finally in situ in Copenhagen on a larger area of The Marble Church showing rust stains due to pyrite oxidation. The cleaning results were evaluated by visual observations, cross sections, and etching of the surface by testing on high gloss marble.
Conclusion: Cleaning of iron-discoloured marble surfaces has been investigated and a new method for removal of rust stained marble has been developed. A solution of 0.1 M cysteine and 0.1 M sodium dithionite in a poultice consisting of Laponite (R) RD/Arbocel (R) BC1000/CMC = 10:10:1 has shown to be a fast, simple, cheap, and non-toxic, do-it-yourself method.

DOI： 10.1186/s40494-016-0081-6

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography  

The crystal structures of bis[2-(pyridin-2-yl)phenyl]rhodium(III) complexes with the metal in an octahedral coordination containing chloride and acetonitrile ligands, namely (OC-6-42)-acetonitrilechloridobis[2-(pyridin-2- yl)phenyl-2N,C1]rhodium(III), [RhCl(C11H8N)2(CH3CN)] (1), thyminate(1-) and methanol, namely (OC-6-42)-methanol(5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin- 1-ido-N1)bis[2-(pyridin-2-yl)phenyl-2N,C1]rhodium(III), [Rh(C11H8N)2(C5H5N2O2)(CH3OH)]CH3OH0.5H2O (2), and thyminate( 1-) and ethanol, namely (OC-6-42)-ethanol(5-methyl-2,4-dioxo- 1,2,3,4-tetrahydropyrimidin-1-ido-N1)bis[2-(pyridin-2-yl)phenyl-2N,C1]rhodium( III), [Rh(C11H8N)2(C5H5N2O2)(C2H5OH)]C2H5OH (3), are reported. The acetonitrile complex, 1, is isostructural with the IrIII analog. In complexes 2 and 3, the monodeprotonated thyminate (Hthym-) ligand coordinates to the RhIII atom through the N atom, and the resulting Rh-N(Hthym) bond lengths are relatively long [2.261 (2) and 2.252 (2) A ° for 2 and 3, respectively] as compared to the Rh-N bonds in the related thyminate complexes. In each of the crystals of 2 and 3, the complexes are linked via a pair of intermolecular N- H O hydrogen bonds between neighbouring Hthym- ligands, forming an inversion dimer. A strong intramolecular O-H O hydrogen bond between the thyminate(1-) and alcohol ligands in mutually cis positions to each other is also observed.

DOI： 10.1107/S2056989016004837

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We prepared enantiomers of chiral Pt-II complexes, Pt(pppb)Cl and Pt(pppb)CN (pppbH=1-pyridyl-3-(4,5-pinenopyridyl)benzene), and measured their CPL (circularly polarized luminescence) spectra for excimer and trimer emission. The contribution of the pinene moiety to CPL was considerably low for the -* emission of the monomer but large for MMLCT (metal-metal-to-ligand charge-transfer) of the excimer and trimer which had a helical structure induced in a face-to-face stacking fashion. The trimer CPL for (+)-Pt(pppb)Cl was larger in intensity than that of excimer CPL; on the other hand, that for (+)-Pt(pppb)CN was opposite in sign compared with that of excimer CPL. We conclude that differences in the excited-state structure of the aggregate between Pt(pppb)Cl and Pt(pppb)CN account for the variation in the CPL spectra. By the aid of TD-DFT calculations it was predicted that the dihedral angle (Cl-Pt-Pt-Cl) was 50-60 degrees or 110-140 degrees for Pt(pppb)Cl aggregates and 160 degrees for Pt(pppb)CN aggregates.

DOI： 10.1002/asia.201500985

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We prepared hydrazone palladium(II) complexes of [PdCl2(HLn)] and [PdCl(L-n)] (n = 1-3) by the reaction of [PdCl2(cod)] or [PdCl2(PhCN)(2)] and the hydrazone ligands of HLn {N'-(pyridin-2-ylmethylene)picolinohydrazide (HL1), N'-[1-(pyridin-2-yl)ethylidene]picolinohydrazide (HL2), and N'-[(6-methylpyridin-2-yOmethylene]picolinohydrazide (HL3)}. The structures of the complexes were determined by X-ray analysis. The hydrazone ligands had kappa N(pyl), kappa N(imine) and kappa N(amidate) kappa N(py2) bidentate coordination modes in [PdCl2(HLn] (1, n = 1; 2, n = 2) and in [PdCl2(HL3)] (3), respectively. In contrast, tridentate coordination modes of kappa N(pyl)), kappa N(imine), kappa N(py2) and kappa N(py1), kappa N(amidate), kappa N(py2) were observed in [PdCl(L-n)] (4, n = 1; 5, n = 2) and in [PdCl(L-n)] (6, n = 1; 7, n = 2; 8, n = 3). Thermal conversion of complexes 1-3 to complexes 6-8 proceeded in acetonitrile. Complexes 4 and 5 were obtained from complexes 1 and 2, respectively, in a basic acetonitrile solution under dark conditions. Complex 4 reverted immediately to complex 1 in an acidic acetonitrile solution that included hydrochloric acid. However, under room light, in the basic acetonitrile solution that included trimethylamine, complex 4 converted photochemically to complex 6. The thermochromic or vapochromic structure conversion of these complexes also occurred in the solid state. On heating at 180 degrees C, the color of the crystals of complexes 1, 2, and 3 changed from yellow to orange in the solid state. H-1 NMR and/or UV vis absorption spectroscopy confirmed that the orange complexes 6-8 were produced. The reddish-orange crystals of complexes 4 and 5 were exposed to hydrogen chloride vapor to yield the yellow products of complexes 1 and 2, respectively.

DOI： 10.1021/acs.inorgchem.5b01128

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography  

The crystal structures of dichloridopalladium(II), -platinum(II) and - rhodium(III) complexes containing 8-(diphenylphosphanyl) quinoline, (SP-4)-[PdCl2(C21H16NP)], (1) [systematic name: dichlorido(8-diphenylphosphanyl-quinoline) palladium(II)], (SP-4)-[PtCl2(C21H16NP)]·CH2Cl2, (2) [systematic name: dichlorido(8-diphenylphosphanylquinoline) platinum(II) dichlorometh-ane monosolvate], and (OC-6-32)-[RhCl2(C21H16NP)2]PF6·0.5CH2Cl2·-0.5CH3OH, (3) [systematic name: cis-dichloridobis(8-diphenylphosphanyl-quinoline) rhodium(III) hexafluoridophosphate dichloromethane/methanol hemisolvate] are reported. In these complexes, the phosphanylquinoline acts as a bidentate ligand, forming a planar asymmetrical five-membered chelate ring. The palladium(II) and platinum(II) complex molecules in (1) and (2), respectively, show a typical square-planar coordination geometry and form a dimeric structure through an intermolecular π-π stacking interaction between the quinolyl rings. The centroid-centroid distances between the stacked six-membered rings in (1) and (2) are 3.633 (2) and 3.644 (2) Å, respectively. The cationic rhodium(III) complex in (3) has a cis(Cl),cis(P),cis(N) (OC-6-32) configuration of the ligands, in which two kinds of intramolecular π-π stacking interactions are observed: between the quinolyl and phenyl rings and between two phenyl rings, the centroid-centroid distances being 3.458 (2) and 3.717 (2) Å, respectively. The PF6 - anion in (3) is rotationally disordered, the site occupancies of each F atom being 0.613 (14) and 0.387 (14). The CH2Cl2 and CH3OH solvent molecules are also disordered and equal site occupancies of 0.5 are assumed.

DOI： 10.1107/S2056989015006076

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Trans-bis(acetylacetonato)-bis(4-methylpyridine)cobalt(III)hexafluorophosphate, [AMPC]PF6, was synthesized and characterized by X-ray diffraction and vibrational spectroscopy. The title compound C22H28-N2O4Co crystallizes with Z = 2 in space group P-1 (#2). The molecular structure and vibrational spectra of this compound were investigated by means of density functional theory (DFT) calculations and the results were compared with the experimental data. The measured IR bands were interpreted in terms of the calculated vibrational normal modes and compared with the tris(acetylacetonate)Co(III) (Co(acac)(3)) and 4-methylpyridine (4-Mepy) vibrational spectra. The scaled theoretical wavenumbers and the structural parameters were in excellent agreement with the experimental data. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.saa.2014.12.019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Reactions of a ruthenium(II) complex containing quinoline-2-carbaldehyde (pyridine-2-carbonyl)hydrazone (HL), trans(P,P)-[RuCl2(PPh3)(2)(HL)] (1), and 3d-metal(II) chlorides resulted in heterodimetallic complexes, [RuCl2(PPh3)(2)-(mu-L)MCl2] (2M, M = Mn, Fe, Co, Ni, Cu, and Zn), in which the deprotonated hydrazonate (L-) bridged two metal ions in the mu-1(Ru)kappa N-2,O:2(M)kappa N-3',N '',N''' mode. The coordination bond lengths around the Ru and M centers suggested that the oxidation states in the complexes 2M could be assigned as Ru-III and M-II; this was also supported by magnetic, electrochemical, and spectroscopic measurements. In addition, oxidation of complex 1 by (NH4)(2)[Ce(NO3)(6)] gave the corresponding mononuclear Ru-III complex with the deprotonated hydrazonate, trans(P,P)-[RuCl2(PPh3)(2)(L)] (3). It is suggested that oxidation of the Ru center lead to the concerted deprotonation from the hydrazone ligand. Addition of excess HClO4 to complex 3 gave a doubly protonated Ru-III complex, 4(ClO4)(2); in this complex the hydrazonate moiety was not protonated, but both the quinolyl and pyridyl N atoms were protonated. Complexes 3 and 4(2+) could be interconverted by the addition of acid or base without changing the oxidation state of the Ru center.

DOI： 10.1246/bcsj.20140381

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Union of Crystallography  

The title compound, [Ru(C&lt
inf&gt
10&lt
/inf&gt
H&lt
inf&gt
8&lt
/inf&gt
N&lt
inf&gt
2&lt
/inf&gt
)&lt
inf&gt
2&lt
/inf&gt
(C&lt
inf&gt
16&lt
/inf&gt
H&lt
inf&gt
12&lt
/inf&gt
N&lt
inf&gt
4&lt
/inf&gt
O)](BF&lt
inf&gt
4&lt
/inf&gt
)&lt
inf&gt
2&lt
/inf&gt
·3CH&lt
inf&gt
2&lt
/inf&gt
Cl&lt
inf&gt
2&lt
/inf&gt
, crystallizes with one complex dication, two BF&lt
inf&gt
4&lt
/inf&gt
&lt
sup&gt
-&lt
/sup&gt
counter-anions and three dichloromethane solvent molecules in the asymmetric unit. The central Ru&lt
sup&gt
II&lt
/sup&gt
atom adopts a distorted octahedral coordination sphere with two 2, 2′-bipyridine (bpy) and one quinoline-2-carbaldehyde (pyridine-2-carbonyl)hydrazone (HL) ligand. The hydrazone ligand has a Z form and coordinates to the Ru&lt
sup&gt
II&lt
/sup&gt
atom via the amide-O and imine-N atoms, affording a planar five-membered chelate ring, while its pyridine-N and quinoline-N donor atoms in the substituents are non-coordinating. The hydrazone N - H group forms an intramolecular hydrogen bond with the quinoline-N atom. In the crystal, the quinoline moiety of HL shows the shortest π-π stacking interaction with the pyridine substituent of HL in a neighbouring complex, the centroid-to-centroid distance being 3.793 (3) Å.

DOI： 10.1107/S2056989015000122

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

In the thyminate(2-)-bridged tetranuclear Cp*Rh-III complexes incorporating a Na+, Ca2+ or Ln(3+) cation, homochiral aggregation of four Rh-III centres was achieved to form metallacalix[4] arene-type clusters. The thyminate(2-) bridged two RhIII and the third metal ionwith a mu(3)-1 kappa N-1:2 kappa N-2(3),O-2:3 kappa O-2 mode in the Na+ and Ca2+ complexes, while in the Ln(3+) analogues it exhibited a different bridging mode, mu(3)-1 kappa N-1:2 kappa N-2(3),O-4:3 kappa O-2.

DOI： 10.1039/c4cc09087j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Six-coordinate [Cu(pdt)(2)(H2O)(2)](2+) and four-coordinate [Cu(pdt)(2)](+) complexes were synthesized and the cross redox reactions were studied in acetonitrile (pdt = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine). Single crystal analyses revealed that [Cu(pdt)(2)(H2O)(2)](BF4)(2) was of pseudo-D-2h symmetry with two axial water molecules and two symmetrically coordinated equatorial pdt ligands, while the coordination structure of [Cu(pdt)(2)]BF4 was a squashed tetrahedron (dihedral angle = 54.87 degrees) with an asymmetric coordination by two pdt ligands: one pdt ligand was coordinated to Cu(I) through pyridine-N and triazine-N2 while another pdt ligand was coordinated through pyridine-N and triazine-N4, and a stacking interaction between the phenyl ring on one pdt ligand and the triazine ring on another pdt ligand caused the squashed structure and non-equivalent Cu-N bond lengths. The cyclic voltammograms for [Cu(pdt)(2)(H2O)(2)](2+) and [Cu(pdt)(2)](+) in acetonitrile were identical to each other and quasi-reversible. The reduction of [Cu(pdt)(2)(H2O)(2)](2+) by decamethylferrocene and the oxidation of [Cu(pdt)(2)](+) by [Co(2,2'-bipyridine)(3)](3+) in acetonitrile revealed that both cross reactions were sluggish through a gated process (the structural change took place prior to the electron transfer) accompanied by slow direct electron transfer processes. It was found that the triazine ring of the coordinated pdt ligand rotates around the C-C bond between the triazine and pyridine rings with the kinetic parameters k = 51 +/- 5 s(-1) (297.8 K), Delta H-double dagger = 6.2 +/- 1.1 kJ mol(-1) and Delta S-double dagger = -192 +/- 4 J mol(-1) K-1. The electron self-exchange process was directly measured using the line-broadening method: k(ex) = (9.9 +/- 0.5) x 10(4) kg mol(-1) s(-1) (297.8 K) with Delta H-double dagger = 44 +/- 7 kJ mol(-1) and Delta S-double dagger = 0.2 +/- 2.6 J mol(-1) K-1. By comparing this rate constant with the self-exchange rate constants estimated from the cross reactions using the Marcus cross relation, the nonadiabaticity (electronic) factors, kappa(el), for the direct electron transfer processes between [Cu(pdt)(2)](+/2+) and non-copper metal (Fe2+ and Co3+) complexes were estimated as ca. 10(-7), indicating that the electronic coupling between the d orbitals of copper and of non-copper metals is very small.

DOI： 10.1039/c5dt01808k

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A reaction of [PdCl2(cod)] (cod = 1,5-cyclooctadiene) and an E/Z mixture of quinoline-2-carbaldehyde (pyridine-2-carbonyl) hydrazone (HL) gave two kinds of Pd-II mononuclear complexes, [PdCl-(Z-L-kappa N-3,N',N '')] (1) and [PdCl2(E-HL'-kappa N-2,N')] (2), where L- is the deprotonated hydrazonate anion and HL' is the quinolinium-hydrazonate zwitterionic form of HL. Complex 2 is gradually converted to 1 in solution, and complex 1 is a good precursor to prepare a Pd-II/Ru-II heterodinuclear complex bridged by hydrazonate, trans(Cl, Cl)-[RuCl2(PPh3)(2)(mu-L)PdCl] (3).

DOI： 10.1039/c5dt02345a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

New iron(II) complexes were synthesized with two tridentate hybrid ligands having phosphorous and nitrogen donor sites, in order to quantitatively estimate the difference of the ligand-field strengths of phosphorous and nitrogen donor sites in cationic metal complexes. Iron(II) complexes with bis(dimethylphosphinoethyl)amine (PNP) and 2,6-bis(diphenylphosphinomethyl)pyridine (PpyP) ligands crystallized as un-symmetric facial-[Fe(PNP)(2)](PF6)(2)center dot CH3NO2 and mer-[Fe(PpyP)(2)](CF3SO3)(2), respectively, as expected from the steric congestion and from the tendency to avoid the mutual trans influence between two phosphorous donor sites. Both complexes are in the low-spin electronic state up to 400 K. The pseudo-D (4h) coordination geometry of the PpyP complex made it possible to separate axial (2 x N) and equatorial (4 x P) contributions to the overall ligand-field by means of a spectrometric method: the difference in the ligand-field strengths by the equatorial Ph2P-donor sites and by the axial 2,6-disubstituted pyridine donor sites is ca. 13,200 cm(-1). A significantly reduced inter-electronic repulsion parameter (425 cm(-1) for both PNP and PpyP complexes) from the value of the free ion (1,060 cm(-1)) indicates covalent interaction between the Fe(II) and P atoms even in these cationic metal complexes. It is shown that the degree of covalency as well as the coordination bond strengths between various metal ions and phosphorous/nitrogen donor atoms is successfully explained by the relative energy levels of interacting atomic orbitals calculated on the basis of the Thomas-Fermi-Dirac potential.

DOI： 10.1007/s10953-014-0182-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A chiral complex, [Fe(HL)(2)](PF6)(2) (1), where HL denotes 2-pyridylmethylidenehydrazono-4-(2-methylimidazoly)methane, was prepared. X-ray structure analysis revealed that it crystallizes as a kryptoracemate of sesquihydrate chiral crystals in the orthorhombic non-centrosymmetric space group P2(1)2(1)2(1) (Z = 8, Z' = 2). Two diastereomeric cationic complexes with opposite configuration reside within the asymmetric unit. KBr pellets prepared using selected single crystals showed enantiomorphous circular dichroism patterns.

DOI： 10.1021/cg500635q

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN CHEMICAL SOC  

Two diastereoisomers of cyclo(Pro-Tyr) have been synthesized simultaneously. The crystal structures and conformations of both cyclo(L-Pro-L-Tyr) and a racemic mixture of cyclo(D-Pro-L-Tyr) and cyclo(L-Pro-D-Tyr), abbreviated as rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr), have been determined by a single-crystal X-ray diffraction study at low temperature. The crystals of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) belong to orthorhombic space group Pna2(1) with a = 10.755 (1), b = 12.699 (1), c = 9.600 (1) angstrom and Z = 4. The tyrosine side chain is folded towards the diketopiperazine (DKP) ring. The DKP ring adopts a twist boat conformation with pseudo symmetry C-2v. The pyrrolidine ring has an envelope conformation with the N5, C4, C7 and C8 atoms in a plane. The crystal of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) is stabilized by hydrogen bonds between amide N2-H2 and carbonyl oxygen O2 in the neighbor. The hydroxyl group of tyrosine residue is also hydrogen bonded to the oxygen of the carbonyl group of the DKP ring in the next molecule. The spectroscopic properties of both isomers are also described.

DOI： 10.5012/bkcs.2014.35.8.2299

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A series of phosphine-substituted ruthenium poly-pyridine complexes, cis(P,Cl)-[Ru(trpy)(Pqn)Cl]PF6 (cis-Cl), trans(P,MeCN)-[Ru(trpy)(Pqn)(MeCN)](PF6)(2) (trans-PN), cis(P,MeCN)-[Ru(trpy)(Pqn)(MeCN)] (PF6)(2) (cis-PN), and [Ru(trpy)(dppbz)(MeCN)] (PF6)(2) (PP), were synthesized and crystallographically characterized (trpy = 2,2':6',2 ''-terpyridine, Pqn = 8-(diphenylphosphanyl)quinoline, and dppbz = 1,2-bis(diphenylphosphanyl)benzene). In electrochemical measurements for cis-PN and PP, the reduction of cis-PN resulted in the formation of trans-PN via cis trans isomerization and that of PP proceeded via a two-electron-transfer reaction. The mechanism of the electrochemical behaviors is discussed through consideration of five-coordinated species, [Ru(trpy)(Pqn)](n+) or [Ru(trpy)(dppbz)](n+) (n = 0-2), formed by liberation of a monodentate labile ligand.

DOI： 10.1021/ic5003644

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Two new cluster compounds having chiral incomplete-cubane-type (Mn3O4)-O-III cores were synthesized using (2S)-2-hydroxy-4-(salicylideneamino)butyrate (H2L-) and characterized by X-ray analysis as well as magnetic susceptibility and spectroscopic measurements. Compound 1 contains a [Mn-3(III)(L)(3)(mu(3)-OMe)](-) cluster anion, while compound 2 prepared in water has a heptanuclear structure bearing two [Mn-3(III)(L)(3)(mu(3)-OH)](-) clusters connected by a Mn-II(H2O)(4) fragment. In both compounds, a moderate intracluster (MnMnIII)-Mn-III center dot center dot center dot)31 ferromagnetic interaction was observed. It was also found that the (Mn3O4)-O-III cluster cores are maintained in solution.

DOI： 10.1246/cl.140067

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The reactions of quinoline-2-carbaldehyde (pyridine-2-carbonyl)hydrazone (HL) and [RuCl2(PPh3)(3)] in various solvents at different temperatures gave the three geometrical isomers trans(Cl,Cl)-, cis(Cl,Cl),trans(P,N)-, and trans(P,P)-[RuCl2(PPh3)(2){HL-O(amide),N(imine)}] (1, 2, and 3, respectively) as well as a linkage isomer trans(P,P)-[RuCl2(PPh3)(2){HL-N(imine),N(quin)}] (4). The molecular and crystal structures of 1-4, together with both E and Z configurational isomers (with respect to the C=N double bond) of the free ligand HL, were determined by X-ray analysis. The ligand HL adopted a Z form and acted as a O(amide),N(imine) bidentate ligand in 1-3, whereas it was an E isomer with a N(imine),N(quin) coordination mode in 4. The gradual thermal conversions of 1 to 2 and of 2 to 3 were observed in dichloromethane and ethanol, respectively, but an interconversion between 3 and 4 was not detected. In dichloromethane, all complexes have a reversible Ru-III/II redox couple in the range 110-412 mV (vs. Ag/Ag+), and the redox potential was largely dependent on the coordination mode of HL and on the mutual configuration of the two PPh3 ligands. Such a potential shift can be interpreted as a combination of Cl-/amide O -donor and PPh3/quinoline N -acceptor orbital contributions to the Ru-II d orbitals [highest occupied molecular orbitals (HOMOs)]. Complexes 3 and 4 in acetonitrile showed a gradual spectral change, probably because of the substitution of the Cl- ligand by the acetonitrile solvent. In addition, 2-4 showed solvatochromic behavior even in noncoordinating solvents that resulted from a blueshift of the metal-to-ligand charge-transfer (MLCT) transition band in polar solvents. These electrochemical and spectroscopic properties are also supported by DFT and time-dependent DFT (TD-DFT) calculations.

DOI： 10.1002/ejic.201301150

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A series of cobalt(III) complexes containing 2-cyanoethylphosphines, [Co(acac)(2){P(CH2CH2CN)(n)Ph3-n}(2)]-BF4 {acac = 2,4-pentanedionate; n = 1 (1), 2 (2), and 3 (3)} have been prepared, and their molecular and crystal structures have been determined. The X-ray diffraction study revealed that these complexes are the trans isomers in the crystals. The Co-P bond lengths are little affected by the number of 2-cyanoethyl substituents on the P atom, which is consistent with a small change of the sigma-donicity among these phosphines. The trans configuration of these complexes is maintained in solution, as revealed by 1H NMR spectroscopy. The 2-cyanoethylphosphines could not form stable cis-isomers of [Co(acac)(2){P(CH2CH2CN)(n)Ph3-n}(2)](+), like the corresponding methylphosphines (PMenPh3-n,). This fact probably results from a strong electron-withdrawing property of a terminal cyano group of phosphine substituent. In the UV-Vis absorption spectra of complexes 1-3, the LMCT transition band is observed in the range of 20500-24000 cm(-1), which is comparable to the analogous PMenPh3-n, complexes, but their intensity is characteristically weaker than that of the corresponding PMenPh3-n complexes. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2013.09.001

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Oxidation of a blue ethanolic mixture containing Co(BF4)(2)center dot 6H(2)O and PClPh2 by tetramethylthiuram disulfide afforded a red- colored complex having a cis-[Co-III(Me(2)dtc)(2)(P)(2)] environment (Me(2)dtc = N, N-dimethyldithiocarbamate), although the yield was relatively low. Single- crystal X- ray crystallography revealed that the product was [Co(Me(2)dtc)(2){(Ph2PO)(2)BF2}] (1), where bis(diphenylphosphinito) difluoroborate was probably formed by hydrolysis of PClPh2 followed by reaction with BF4 in ethanol. The same complex was also prepared by hydrolysis of cis-[Co(Me(2)dtc)(2)(PHPh2)(2)]BF4 in a mixture of acetonitrile, methanol and water. The molecular structure and spectroscopic properties of complex 1 were compared with those of the corresponding Ph2POMe complex, cis-[Co(Me(2)dtc)(2)(Ph2POMe)(2)]BF4. (C) 2013 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.ica.2013.10.028

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DOI： 10.1002/jhet.1827

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

New rutheniurn(II or III) complexes with general formula [Ru(O-N)(bpy)(2)](n+) (O-N = unsymmetrical bidentate phenolate ligand; bpy = 2,2'-bipyridine) were synthesized, and their crystal structures and electrochemical properties were characterized. Ru-II complexes with, 2-(2-imidazolinyl)phenolate (Himn(-)) or 2-(1,4,5,6-tetrahydropyrimidin-2-yl)phenolate (Hthp(-)) could be deprotonated by addition of excess KO'Bu, although the deprotonated species were easily reprotonated by. exposure to air. Unlike these Run complexes, their Ru-III analogs showed interesting ligand oxidation reactions upon addition of bases. With Ru-III (Himn)(bpy)(2)](2+), two electron oxidation of Himn(-) and reduction of the Rum center resulted in conversion of the 2-irnidazolinyl group, to a 2-imidazolyl group. On the other hand, the corresponding Hthp- complex exhibited four electron oxidation of the ligand to form 2-(2-pyrirnidyl)phenolate (pym-). These aromatization reactions of imidazolinyl and 1,4,5,6-tetrahydropyrimidyl groups were also achieved by the electrochemically generated Rum complexes.'

DOI： 10.1021/ic401662v

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Four cobalt(III) complexes with the formula of [Co(Ln)2] - bearing tridentate amine-amidato-phenolato-type ligands (Ln: n = 1-4) were synthesized. All of the complexes were characterized by 1H NMR spectroscopy and X-ray analysis. The geometrical selectivity was found to depend on the flexibility of the amine-amidato chelate in combination with the planar 2-oxybenzamido 6-membered chelate
that is, the amine-amidato 5-membered chelate took the mer-type geometry, and the 6-membered chelate took the fac-type geometry. In most of the mer-type complexes, intermolecular double hydrogen bonds via amidato(O) and amino group were selectively formed between their enantiomeric pairs of mononuclear complexes. In the case of two chiral ligands {L22- = 2-amino-1-(2-oxybenzamido)propane
L32- = trans-1-amino-2-(2-oxybenzamido)cyclohexane}, [Co(L3)2]- showed diastereoselectivity while [Co(L2)2]- did not. Furthermore, PPh4[Co(L1)2] (L12- = 2-amino-1-(2-oxybenzamido)-2-methylpropane) showed an apparent solvatochromic behavior in several solvents. Although the molecular structures of [Co(L2 or L3)2]- are quite similar to that of [Co(L1) 2]-, these complexes did not exhibit such a solvatochromic behavior. © 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2013.01.011

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Several new iridium(III) and rhodium(III) complexes bearing 5-methyltetrazolate (MeCN4-) have been prepared, and their structures in the crystals and in solution have been determined by X-ray analysis and by NMR spectroscopy, respectively. In the crystals of the mononuclear complexes, kappa N-2-coordination of MeCN4- was observed when the ancillary ligand was 2,2'-bipyridine (bpy): [Cp*M(bpy)(MeCN4-kappa N-2)]PF6 (Cp* = eta(5)-C5Me5; M = Ir: 1 and Rh: 2), while the corresponding complexes with 2-(2'-pyridyl)phenyl (ppy(-)) were confirmed to have the kappa N-1-coordination of MeCN4-: [Cp*M(ppy)(MeCN4-kappa N-1)] (M = Ir: 3 and Rh: 4). In solution, the Ir-III complexes (1 and 3) were robust enough to maintain their molecular structures, but the Rh-III complexes (2 and 4) existed as an equilibrium mixture of the kappa N-1- and kappa N-2-isomers. In addition to the Ir-III-Ir-III and Rh-III-Rh-III homodinuclear complexes bridged by MeCN4- (5-8), the corresponding heterodinuclear Ir-III-Rh-III complexes (9-12) were prepared using the mononuclear Ir-III complexes (1 and 3) as precursors. The molecular structures of these dinuclear complexes were also characterised. Interestingly, both of the heterodinuclear complexes comprised of Cp*M(bpy)(2+) and Cp*M'(ppy)(+) fragments, [Cp*M(bpy)(mu-MeCN4)M'(ppy)Cp*](PF6)(2) (M = Ir, M' = Rh: 10 and M = Rh, M' = Ir: 11), exhibited selective crystallisation of a specific mu-kappa N-1(M'-ppy):kappa N-3(M-bpy) isomer. In solution, the dinuclear complexes with a Rh-N(MeCN4) bond and more than one positive charge (6 and 9-11) showed a dissociation equilibrium, while monocationic MeCN4-bridged complexes (7, 8 and 12) were inactive for dissociation. Furthermore, the heterodinuclear complexes of 9-12, as well as the Rh-III-Rh-III complex of 8, exhibited a bridging isomerisation, which would proceed via a eta(2):eta(2)-intermediate without dissociation of Cp*M(bpy or ppy) fragments.

DOI： 10.1039/c3dt51667a

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A series of cobalt(III) complexes containing 2-cyanoethylphosphines, [Co(Me(2)dtc)(2){P(CH2CH2CN)(n)Ph3-n}(2)]BF4 {Me(2)dtc(-): N,N-dimethyldithiocarbamate; n =1 (1), 2 (2), and 3 (3)} have been prepared, and their molecular structures in the crystals and in solution have been characterized. X-ray analysis revealed that all complexes isolated as single-crystals were the trans-isomers. The Co-P bond lengths for the 2-cyanoethylphosphines in complexes 1-3 are almost invariant to the number of 2-cyanoethyl substituent groups. Unlike related complexes with other monodentate P-donor ligands, complexes 1-3 in solution showed dissociation and isomerization equilibriums, which were achieved immediately after dissolving the crystals. These characteristic features of the complexes would result from the weak sigma-donor and pi-acceptor abilities of 2-cyanoethylphosphines. Furthermore, mixing of complex 1 and NaN3 in acetonitrile gave cis-[Co(Me(2)dtc)(2)(N-3){P(CH2CH2CN)Ph-2}] quantitatively, and refluxing the mixture resulted in the phosphine-tetrazolate complex, [Co(Me(2)dtc)(2)(Ph2PCH2CH2CN4-(KP)-P-2,N-1)] (4).

DOI： 10.1246/bcsj.20120148

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The crystal structure of trans-[Cr(tn)(2)Cl-2]ClO4 (tn = 1,3-propanediamine) is determined by a single-crystal X-ray diffraction study at 185 K. The Cr atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two chlorine atoms in trans position. The orientations of two six-membered rings in the complex cation are in an anti chair-chair conformation with respect to each other. The mean Cr-N(tn) and Cr-Cl bond lengths are 2.0862(2) and 2.3112(6) respectively. The ClO (4) (-) anions have a slightly distorted tetrahedral geometry with Cl-O lengths and O-Cl-O angles influenced by the hydrogen bonding. The crystal packing is stabilized by several hydrogen bonds. The infrared and electronic absorption spectral properties are also described along with the results of X-ray crystallography.

DOI： 10.1134/S0022476612020291

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New Schiff base (HL) ligand is prepared via condensation of 2-aminophenol and 4-(dimethylamino) cinnamaldehyde. The cobalt complex with the formula of [Co(L)(2)(MePy)(2)]PF6 is prepared in good yield from the reaction of the ligand with cobalt(II) acetate. The compounds were characterized by the analytical and spectroscopic methods. The ligand (HL) behaves as a bidentate ligand and coordinates to the cobalt ions via the nitrogen and oxygen atoms with mononuclear structure. The ligand (HL) has been structurally characterized by X-ray crystallography. There is O-H center dot center dot center dot N-H bond linking the molecules together. FT-IR spectra show that HL is coordinated to the cobalt ion in a mono-negative bidentate manner with ON donor sites of the azomethene N and deprotonated phenolic-OH. There are two methylpyridine molecules apically coordinated to Co(III) ion in octahedral environment. Electrochemical properties were investigated as metal centres in the dimethylformamide solvents. The Co(III) complex exhibit both irreversible reductive (CoIII/CoII; Epc, -1.24 V) and oxidative (CoII/CoIII; Epa, +0.79 V, respectively) responses in cyclic voltammetry. Thin film of nano-sized [M(L)(2)(MePy)(2)]PF6 complex was formed by surface layer-by-layer chemical deposition method. The formation of uniform thin films of nano-crystalline metal complex is dependent on metal and ligand concentrations.

DOI： 10.1007/s10904-011-9535-1

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A host-guest complex, [Fe-III(H3L)][Fe-III(L)][Cr-III(ox)(3)]center dot 3H(2)O (1), where H3L and L3- serve as hexadentate ligands, was prepared. In 1, three properties are united: the homochiral assembly of chiral [Fe-III(H3L)](3+) and [Fe-III(L)] into a conglomerate structure, the chiral recognition of the host Fe-III assembly to the guest [Cr-III(ox)(3)](3-) and the spin-crossover of [Fe-III(H3L)](3+).

DOI： 10.1039/c2ce25612f

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Mononuclear Mn(III) complexes have been prepared via the Mn(II) reaction of an equimolar of Schiff-bases derived from reaction of 2-hydroxy-3-methoxybenzaldehyde or 2-hydroxy-5-methoxybenzaldehyde with 1,2-diaminopropane. Axial ligands L include: pyridine (py) and H2O. The resulting complexes have been characterized by FT-IR and UV-vis spectroscopy. The crystal structures of the complexes were determined and indicate that in the solid state the complex adopts a slightly distorted octahedral environment of the imine N and hydroxo O with the two axial ligands. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Mn-III-Mn-II is electrochemically quasi-reversible. Thermal stability of these complexes was determined by TG and DTG. Layers of these complexes were formed on nanostructure zinc oxide thin film and a red shift was observed when zinc oxide thin film is modified by complex. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.saa.2011.03.055

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Reactions of [Cp*Ir{NSC(NR2)S}] (Cp* = eta(5)-C5Me5, R = Me or Et,) with alkyl halides (MeI or BnBr) in acetonitrile gave the N-alkylated products, [Cp*Ir{R'NSC(NR2)S}] (R' = Me or Bn). These complexes readily reacted with PPh3 to give adducts. In contrast, [Cp*Ir{SN=C(NR2)S}] formed their PPh3 adducts, which gave thermally stable S-alkylated products by reactions with alkyl halides.

DOI： 10.1246/cl.2011.831

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Density functional theory (DFT) at B3LYP/6-31++G** level has been applied to study structural, electronic and bonding characteristics of some 2-oxo-1,2,3,4-tetrahydropyrimidin-5-carboxamides (THPMs) and their oxidized forms 2-oxo-1,2-dihydropyrimidin-5-carboxamides (DHPMs). Results of this study show that for these THPMs, the six-member ring adopts a boat conformation with a pseudo-axial orientation of the C(4)-substituent. Experimental and theoretical (1)H NMR data obtained for THPMs and their corresponding oxidized forms (DHPMs) are correlated. Thermochemical analysis on THPMs and their corresponding oxidation products show that the oxidation reaction of THPMs to DHPMs is endothermic. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molstruc.2011.05.017

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Cobalt(HI) complexes with N-(aminoalkyl)salicylamide dianions, Ln(2-) (n = 1-4), have been prepared and their molecular and crystal structures have been determined. The geometric (mer- or fac-) selectivity of [Co(Ln)(2)](-) complexes was dependent on the number of the amine-amidato chelate ring member. Intermolecular homochiral hydrogen-bonds and solvatochromic behavior of the complexes were also observed.

DOI： 10.1246/cl.2011.696

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The tetrafluoroborate salt of bis{8-(diphenylphosphino)quinoline}copper(I), [Cu(Ph(2)Pqn)(2)]BF(4), afforded orange prismatic (2O) or yellow columnar (2Y) crystals, dependent on the solvent and concentration of the recrystallization solution used. X-ray analysis revealed that crystals of 2O and 2Y had the same composition and exhibited different crystal systems: 2O was triclinic, with space group P (1) over bar and Z = 2, and 2Y was monoclinic with space group P2(1)/c and Z = 4. In these crystals, the tetrahedral copper(I) complex exhibited a strong "rocking distortion" toward a trigonal pyramidal coordination geometry (by a slide translation of one of the unsymmetrical bidentate chelating ligands along the tetrahedral edge). In addition, both the 2O and 2Y complexes showed a "flattening distortion", meaning that the dihedral angle between the two chelate planes were off-perpendicular and oriented toward opposite directions, which resulted in a pair of distortion isomers: syn clinal (sc: 2O) and anti clinal (ac: 2Y). (31)P CP-MAS NMR spectroscopy indicated that 2O and 2Y could be distinguished. Both isomers exhibited inequivalent P atoms, but a larger difference in chemical shift was observed in 2Y. TD-DFT calculations reproduced the difference in spectra between the orange- and yellow-colored complexes, which originated from metal-to-ligand charge-transfer transitions.

DOI： 10.1021/ic1024636

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We investigated polymorphism in [Pt(fdpb) Cl] [Hfdpb = 1,3-bis(5-trifluoromethyl-2-pyridyl)benzene]. The following polymorphs of the complex were crystallized: yellow [Form Y; orthorhombic, Pca2(1), a = 23.4336(14) angstrom, b = 4.6377(2) angstrom, c = 15.7845(9) angstrom, Z = 4], red [Form R; monoclinic, C2/c, a = 21.3619(12) angstrom, b = 13.5629(7) angstrom, c = 13.6974(6) angstrom, beta = 122.301(2)degrees, Z = 8], and dark green [Form G; monoclinic, P2(1)/a, a = 6.7953(4) angstrom, b = 18.2519(12) angstrom, c = 13.5199(8) angstrom, beta = 96.039(2)degrees, Z = 4]. The yellow color of Form Y was due to the influence of stacking on the pi,pi* absorption of the Pt molecule; the red color of Form R originated from a MMLCT absorption due to Pt-Pt interactions in a closely stacked dimer; and the dark green of Form G was attributed to the absorption of a linear array of Pt-II complexes. The polymorphs emitted luminescence at around 550 (Form Y), 670 (Form R), and 750 nm (Form G). Mechanical grinding of the crystals changed the polymorphs from the crystalline to the amorphous phase; the emission spectra of ground samples of Forms Y and R, observed at 750 nm, were identical. When the amorphous solid was heated to around 500 K, the emission spectrum was blueshifted to 670 nm due to a phase transition from amorphous to crystalline. Heating also caused a crystal-crystal transformation; phase transitions from Form G to Form R and Form R to Form Y proceeded at 430-470 and 540-560 K, respectively.

DOI： 10.1002/ejic.201001359

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A series of mononuclear Mn-II, Mn-III, and Mn-IV complexes was prepared using a single tripodal ligand (H3L). Addition of a cation (NH4+, K+, Na+) to [(MnL)-L-III] showed a pronounced effect on the redox potentials. Different variants of Jahn-Teller distortion, axial elongation and compression, were observed in the Mn-III complexes.

DOI： 10.1039/c1cc12418h

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A reaction of [Cp*IrCl(2)](2) {Cp* = eta(5)-C(5)(CH(3))(5)}and 2-mercaptobenzimidazole (H(2)bimt) in methanol in a 1:2 molar ratio gave a yellow complex of [Cp*IrCl(2)(H(2)bimt)]center dot CH(3)OH (1). In compound 1 the H(2)bimt acts as a monodentately S-donating (kappa S) ligand. A similar reaction of [Cp*IrCl(2)](2) and H(2)bimt in the presence of NaOCH(3) (molar ratio of 1:2:2) gave an orange product (2) on addition of excess amount of NH(4)PF(6). Compound 2 was composed of an unsymmetrical dinuclear complex cation, [(Cp*IrCl)(2)(mu-Hbimt)(mu-H(2)bimt)](+), a PF(6) anion, and water molecules of crystallization. In the complex cation, H(2)bimt bridges two Ir(III) centers by S atom in the mu-kappa S:kappa S mode, while the monodeprotonated Hbimt ligand bridges via S and N atoms in the mu-kappa S:kappa N(1) mode. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2010.05.053

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Mononuclear [Fe(H(2)L(R))(2)]X(2) (R = H, 2-Me, 5-Me, 2-Et-5-Me; X = ClO(4), BF(4)) and dinuclear [Fe(2)(H(2)L(R))(3)]X(4) complexes containing imidazole-4-carbaldehyde azine (H2LH) and its derivatives prepared by condensation of 4-formylimidazole, 2-methyl- or 5-methyl-4-formylimidazole, or 2-ethy1-4-methy15-formylimidazole, with hydrazine in a 2:1 mole ratio in methanol, were prepared and their magnetostructural relationships were studied. In the mononuclear complexes, H(2)L(R) acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H(2)L(R) acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate structure. At room temperature, [Fe(2)(H(2)L(H))(3)](ClO(4))(4) and [Fe(2)(H(2)L(2)-me)(3)](ClO(4))(4) were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H(2)L(2-Me) with electron-donating methyl groups being stronger than H(2)L(H), with the order of the ligand field strengths being H(2)L(2-me) &gt; H(2)L(H). However, in the mononuclear [Fe(H(2)L(H))(2)](ClO(4))(2) and [Fe(H(2)L(2-Me))(2)](ClO(4))(2) complexes, a different order of ligand field strengths, H(2)L(H) &gt; H(2)L(2-Me), was observed because [Fe(H(2)O)(2)](ClO(4))(2) was in the LS state while Fe(H(2)L(2-me))(2)](ClO(4))(2) was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H(2)L(2-Me) ligand and the other ligand in Fe(H(2)L(2-Me))(2)](ClO(4))(2) is responsible for the observed change in the spin state. The same is true for [Fe(H(2)L(2-Et-5-Me))2](ClO(4))(2), while [Fe(H(2)L(5-Me))2](ClO(4))(2) does not involve such a steric congestion and stays in the LS state over the temperature range 5-300K. Two kinds of crystals (polymorphs) were isolated for [Fe(2)(H(2)L(H))(3)](BF(4))(4) and [Fe(2)(H(2)L(2-Et-5-Me))(3)](ClO(4))(4), and they exhibited different magnetic behaviors. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ccr.2009.11.016

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Surface tension of anionic surfactant solutions, sodium dodecyl sulfate (SDS) or sodium dodecylbenzenesulfonate (SBS) decreases remarkably in the presence of [Co(NH3)(6)]X-3 (2.50 mM) (X- = Cl-, Br-, I-, or ClO4-) at 298 K, depending on the kind of counter anion X. The magnitude of reduction is in the order ClO4- &gt; I- &gt; Br- &gt; Cl- for SDS solutions and ClO4- &gt; Cl- &gt; Br- &gt; I- for SBS solutions at 0.03 mM surfactant concentrations.

DOI： 10.1246/cl.2010.306

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT UNION CRYSTALLOGRAPHY  

The title compound, C27H27N7O6, a Schiff base, was synthesized by the reaction of triethylenetetramine with 3-nitrobenzealdehyde. There are two independent molecules in the asymmetric unit. The central aromatic ring in one molecule makes dihedral angles of 23.99 (7) and 20.06 (6)degrees with the two terminal rings; for the second molecule, these angles are 26.14 (6) and 24.64 (6)degrees.

DOI： 10.1107/S1600536810003168

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The "solvent effect" on the solid-state luminescence of a neutral complex, [Ru(dbb)(2)(CN)(2)] (dbb = 4,4'-di-tert-butyl-2,2'-bipyridine), was presented. The crystals of this complex showed a variety of luminescence color from orange to dark-red, depending on the acceptor number of the solvent included in the crystal as a solvent of crystallization. The luminescence change was very similar to the solvatochromism in solution, which was attributed to the local donor-acceptor interaction between the CN group and the solvent molecules. The dynamic shift observed in the transient emission spectrum of the crystalline powder was accounted for by the solvent molecule reorganization. X-ray crystallography of [Ru(dbb)(2)(CN)(2)]center dot 3(CH3)(2)CO showed the complex molecule having an approximate C-2 symmetry and very weak interactions between the acetone molecules and the CN groups. A three-dimensional network constructed by acetone molecules was observed in the hydrophobic space consisting of t-butyl groups in dbb ligands. A thin film of the complex showed vapochromic behavior such that the luminescence changed depending on the solvent of crystallization. This suggests a capability for organic molecule discrimination using the complex in the solid state.

DOI： 10.1021/ic9021596

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Nickel(II) complexes containing P-N-type bidentate hybrid ligands of 2-aminoethylphosphanes (RR&apos;Pea; RR&apos; = Ph(2) or MePh) or 8-quinolylphosphanes (RR&apos;Pqn), namely [Ni(P-N)(2)]-(BF(4))(2) [P-N = Ph(2)Pea (1), MePhPea (2), Ph(2)Pqn (3), or MePhPqn (4)] have been prepared, and their structural, spectroscopic, and electrochemical properties determined. The crystal structure analysis indicates that the 2-aminoethyl-phosphane complexes (1 and 2) have a square-planar coordination geometry around the Ni(II) center with a cis(PP) configuration, whereas the 8-quinolylphosphane complexes (3 and 4) exhibit a severe tetrahedral distortion because of the steric repulsion between the ortho-H atoms in the mutually cis-positioned quinolyl rings. Complexes I and 2 maintain their diamagnetic square-planar four-coordinate structure on acetonitrile solution, whereas complexes 3 and 4 show paramagnetic behavior. Spectroscopic and electrochemical measurements suggest that the ligand-field strengths of these four P-N-type ligands increase in the order Ph(2)Pqn (3) &lt; MePhPqn (4) &lt; Ph(2)Pea (1) &lt; MePhPea (2). The Ph(2)Pqn complex 3 is readily reduced by Zn powder to afford the corresponding nickel(I) complex [Ni(Ph(2)Pqn)(2)]BF(4) (5). The crystal structure of complex 5 reveals that the Nil ion adopts a distorted tetrahedral coordination geometry with slightly longer (approximate to 0.05 angstrom) Ni-P and Ni-N bond lengths than those in the corresponding Ni(II) complex 3.

DOI： 10.1002/ejic.200900767

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The crystal structures of rac- and Lambda-[M-III(tn)(3)]P3O9 center dot nH(2)O (M = Co, Cr; tn = 1,3-diaminopropane = trimethylenediamine; P3O9 = cyclotriphosphate(3-))were determined by single-crystal X-ray analyses. In rac-[Co(tn)(3)]P3O9 center dot 7.3H(2)O, the [Co(tn)(3)](3+) cations with the same absolute configuration (Delta or Lambda) and the P3O93- anions are alternately arrayed and connected by multiple NH center dot center dot center dot O hydrogen bonds to form a homochiral columnar structure. Adjacent homochiral columns with opposite chirality are connected by intercolumn hydrogen bonds to form a racemic pair of columns. The crystal structure of rac-[Cr(tn)(3)]P3O9 center dot 7.5H(2)O is similar to that of the Co complex; however, there exist two types of racemic pairs of columns. In the crystal of Lambda-[Co(tn)(3)]P3O9 center dot 2.5H(2)O, a pair of columns consisting of alternately stacked Lambda-[Co(tn)(3)](3+) cations and P3O93- anions are linked by hydrogen bonds. Neighboring column pairs are further linked by hydrogen bonds to form a three-dimensional (3-D) sheet structure. The crystal structure of Lambda-[Cr(tn)(3)]P3O9 center dot 2.5H(2)O is isomorphous with the Co complex. The circular dichroism (CD) spectra of aqueous solutions of Lambda-[M(tn)(3)]Br-3 (M = Co, Cr) change when P3O93- is added, and the changes were explained by ion pair formation through hydrogen bonds.

DOI： 10.1039/c0nj00270d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Mononuclear [Fe(H2L2-Et-5-Me)(2)](2+) and dinuclear [Fe-2(H2L2-Et-5-Me)(3)](4+) complexes, where H2L2-Et-5-Me denotes 2-ethyl-5-methylimidazole-4-carbaldehyde azine, were prepared and isolated as the perchlorate salts, and their structures and magnetic properties were studied. In file mononuclear complex, the ligand acts as ail unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom. The complex was in the HS state above 50 K. In the dinuclear complex, each ligand acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate structure. Two types of crystals, plates and blocks, were isolated for the dinuclear complex. The plate crystals exhibited a sharp spin transition, [LS-HS] &lt;-&gt; [HS-HS], with no [LS-LS] state being observed. The block crystals remained in the [HS-HS] state above 50 K.

DOI： 10.1246/bcsj.82.1497

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In the title dinuclear iridium(III) complex, [Ir-2(C10H15)(2)-(C5H5N2S)(2)]I-2, the iridium(III) atoms are bridged by 2-(aminosulfanyl) pyridine(1-) [(2-py)SNH] ligands in a mu-(2-py) SNH-kappa N-2(py),N(NH):kappa N(NH) mode. The dinuclear complex cation lies on a crystallographic inversion center, resulting in a planar Ir2N2 ring with an Ir-N(py) bond length of 2.085 (9) angstrom and bridging Ir-N(NH) bonds of 2.110 (9) and 2.113 (9) angstrom. The two (2-py) S units have mutually anti configurations with respect to the Ir2N2 ring

DOI： 10.1107/S1600536809037167

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Mononuclear [Fe(H(2)L(R))(2)](2+) and dinuclear [Fe(H(2)L(R))(3)](4+) (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H(2)L(H)) and its derivatives (H(2)L(2-Me) and H(2)L(5-Me)) prepared from the condensation reaction of 4-formylimidazole or 2-methyl- or 5-methyl-4-formylimidazole with hydrazine (2:1) were prepared, and their magnetostructural relationships were studied. In the mononuclear complexes, H(2)L(R) acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H(2)L(R) acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe(2)(H(2)L(H))(3)](CIO(4))(4) and [Fe(2)(H(2)L(2-Me))(3)](CIO(4))(4) were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H(2)L(2-Me) with electron-donating methyl groups being stronger than H(2)L(H), with the order of the ligand field strengths being H(2)L(2-M) (e)&gt; H(2)L(H), However, in the mononuclearjFe(H(2)L(H))(2)](CIO(4))(2) and [Fe(H(2)L(2-Me))(2)](CIO(4))(2) complexes, a different order of Iigand field strengths, H(2)L(H) &gt; H(2)L(2-Me), was observed because [Fe(H(2)L(H))(2)] (CIO(4))(2) was in the LS state while [Fe(H(2)L(2-Me))(2)](CIO(4))(2) was in the HS state at room temperature. X-ray structural studies revealed that the interligand steric repulsion between a methyl group of an H(2)L(2-Me) ligand and the other ligand in [Fe(H(2)L(2-Me))(2)](CIO(4))(2) is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe2(H(2)L(H))(3)](BF(4))(4), and both exhibited a sharp spin transition, [LS-HS] &lt;-&gt; [HS-HS], The spin transition of the block crystals is more abrupt with a hysteresis, T(c)up arrow = 190 K and T(c)down arrow = 183 K with Delta T= 7 K.

DOI： 10.1021/ic900977m

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In the title complex, [Mn-2(C19H2ON2O4)(2)(C19H22N2O4)(2)](PF6)(2), the Mn-III ion is coordinated by two O [Mn-O = 1.855 (2) and 1.887 (2) angstrom] and two N [Mn-N = 1.982 (3) and 1.977 (3) angstrom] atoms from the tetradentate Schiff base ligand and a coordinated axial ligand [Mn-O = 2.129 (2) angstrom]. The centrosymmetric dimer contains two Jahn-Teller-distorted Mn-III ions, each in a nearly octahedral geometry, connected through two phenolate bridges from two ligands. There are two stereogenic centers. The methyl group and the H atom attached to the middle propane C atom are disordered over two positions with occupancy factors in the ratio 0.58:0.42. The crystal is therefore a mixture of two diasteroisomers, viz. RS/SR and RR/SS. In the axial ligand, the two benzene rings form a dihedral angle of 56.97 (5)degrees and the dihedral angle between the two MnNC3O chelate rings is 2.98 (12)degrees

DOI： 10.1107/S1600536809028591

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The title Schiff base, C(21)H(26)N(2)O(2), contains two intramolecular O-H center dot center dot center dot N hydrogen bonds between the hydroxyl groups and the nearest imine N atoms, each leading to a six-membered ring. Weak C-H center dot center dot center dot O hydrogen bonds result in a ladder network running along the a axis. In addition, intermolecular C-H center dot center dot center dot pi interactions serve to stabilize the extended structure.

DOI： 10.1107/S1600536809022855

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In the title complex, [Ni(C(21)H(24)N(2)O(4))], the Ni(II) ion has a slightly distorted square-planar geometry, coordinated by the two N and two O atoms of a new tetradentate Schiff base ligand. The dihedral angle between the planes of the two NiNC(3)O chelate rings is 14.37 (12)degrees.

DOI： 10.1107/S1600536809019965

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Several (azido)iridium(III) complexes having a pentamethylcyclopentadienyl (Cp*) group, [Cp*Ir(N(3))(2)(Ph(2)Ppy-kappa P)] (1: Ph(2)Ppy = 2- diphenylphosphinopyridine), (Cp*Ir(N(3))(Ph(2)Ppy-kappa P,kappa N)]CF(3)SO(3) (2), [Cp*Ir(N(3))(dmpm)]PF(6) (3: dmpm = bis(dimethylphosphino)methane), [Cp*Ir(N(3))(Ph(2)Pqn)]PF(6)center dot CH(3)OH (4 center dot CH(3)OH: Ph(2)Pqn = 8- diphenylphosphinoquinoline), and [Cp*Ir(N(3))(pybim)] (5: Hpybim = 2-(2- pyridyl)benzimidazole) have been prepared and their crystal structures have been analyzed by X-ray diffraction. In complex 1, the Ph(2)Ppy ligand is only coordinated via the P atom (-kappa P), while in 2 it acts as a bidentate ligand through the P and N atoms (-kappa P,kappa N) to form a four-membered chelate ring. Comparing the structural parameters of the chelate ring in 2 with those of a similar five-membered chelate ring formed by ph(2)Pqn in 4, it became apparent that the angular distortion in the Ph(2)Ppy-kappa P,kappa N ring was remarkable, although the Ir-P and Ir-N bonds in the Ph(2)Pqn-kappa P,kappa N ring were not elongated very much from the corresponding bonds in the Ph(2)Pqn-kappa P,kappa N ring. In the pybim complex 5, the five-membered chelate ring was coplanar with the pyridine and benzimidazolyl rings. With the related (azido)iridium(III) complexes analyzed previously, comparison of the structural parameters of the Ir-N(3) moiety in (Cp*Ir(III)(N(3))(L-L&apos;)(+/0) complexes reveals all anomalous feature of the 2,2&apos;-bipyridyl (bpy) complex, [Cp*Ir(N(3))(bpy)]PF(6). (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2009.04.010

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The Co-II atom in the title monomeric Schiff base complex, [CoCl2(C21H22N2)], is bonded to two Cl atoms and to two N atoms of the Schiff base ligand N,N &apos;-bis[(E)-3-phenylprop-2-en-1-ylidene]propane-1,3-diamine in a distorted tetrahedral geometry. The molecule has an idealised mirror symmetry, but is not located on a crystallographic mirror plane.

DOI： 10.1107/S1600536809016274

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

It has been observed that, at 25.0 +/- 0.1 degrees C, [Co(NH(3))(6)](ClO(4))(3), [Co(en)(3)](ClO(4))(3), [Co(bpy)(3)](ClO(4))(3), and [Co(phen)(3)](ClO(4))(3) in the regions of 1.25-5.00 mM aqueous solutions cause a significant surface tension reduction (STR) of water by the surfactants, sodium dodecylsulfate (SIDS) and sodium dodecylbenzenesulfonate (SBS), suggesting the formation of the 1:1 and 1:2 association complexes, {[complex](3+)(S(-))}(2+) and {[complex](3+)(S(-))(2)}(+) where [complex](3+) =[Co(NH(3))(6)](3+), [Co(en)(3)](3+), [Co(bpy)(3)](3+), or [Co(phen)(3)](3+), S(-) = DS(-) or BS(-). The effect of [Co(en)(3)](3+) on STR in SDS-water system is the largest due to a strong hydrophilic interaction between amino protons of [Co(en)(3)](3+) and sulfate oxygen atoms of DS(-). The effects of [Co(en)(3)](3+), [Co(bpy)(3)](3+), and [Co(phen)(3)](3+) on STR in SBS-water system are significant and almost same, meaning that the hydrophilic interaction between [Co(en)(3)](3+) and the sulfonate group is comparable to the hydrophobic interaction between [Co(bpy)(3)](3+) or [Co(phen)(3)](3+) and the phenyl group of BS(-). The Co(III) complexes of 1.25-5.00 mM are precipitated as {[complex](3+)(S(-))(3)} at 0.0295-0.173 mM of S(-). The precipitates, {[Co(bpy)(3)](3+)(S(-))(3)} and {[Co(phen)(3)](3+)(S(-))(3)} can be dissolved at higher molar ratio of [S(-)]/[complex(3+)] than 3.5 for SDS and 4.0 for SBS. This observation suggests that the aggregated premicelle [Co(bpy or phen)(3)](2)(DS)(7)(-) or aggregated premicelle [Co(bpy or phen)(3)](BS)(4)(-) is formed. (C) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2008.12.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Lanthanide complexes are of great importance for their prospective applications in wide range of science and technology. Chiral lanthanide complexes can constitute stereo-discriminating probes in biological media, owing to the luminescent properties of the rare-earth ions. Sensitized emission with narrow bandwidth, having fast radiation rate and high emission quantum efficiency are the main perspective for synthesizing the complexes. Attention has been given on remarkable chirality with high dissymmetry factors (g = Delta epsilon(ext)/epsilon(max)) of the complexes. For this purpose, beta-diketonato ligands with chiral BINAPO (1,1'-binapthyl phosphine oxide) ligand were chosen to achieve the goal. The complexes [Ln(TFN)(3)-(S-BINAPO)](TFN = 4,4,4- trifluoro-1(2-napthyl)-1,3-butanedione), [Ln(HFT)(3)(S-BINAPO)] (HFT = 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione) and [Ln(HFA)(3)(S-BINAPO)](hfa = hexafluoroacetylacetonate) (where Ln = Yb, Eu) were synthesized. The complex, [Eu(TFN)(3)(S-BINAPO)] gives strong red emission at 615 nm with narrow emission band (&lt; 10 nm) when excited by 465 nm light with quantum efficiency 86%. The dissymmetry factors (g = Delta epsilon(ext)/epsilon(max)) corresponding to the F-7(1) -&gt; D-5(0) transition at 590 nm is 0.091 for [Eu(TFN)(3)(S-BINAPO)] and for [Yb(hfa)(3)(S-BINAPO)](hfa = hexafluoroacetylacetonate) corresponding to the F-2(7/2) -&gt; F-2(5/2) transitions is 0.12, are among the largest values for both Eu and Yb complexes to date, respectively. The Eu complexes, [Eu(HFT)(3)(S-BINAPO)] and [Eu(TFN)(3)(S-BINAPO)] are found to be spontaneously emissive, showing bright red emission, when placed in sunlight or even in the laboratory when light is switched on. (c) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2008.03.093

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The structure, spectroscopic, and electrochemical properties of [Co{(BA)(2)pn}(L)(2)]ClO(4) complexes, where (BA)(2)pn = N,N &apos;-bis(benzoylacetone)-1,3-propylenediimine dianion and the two ancillary ligands (L) are pyridine, py (1), and 4-methylpyridine, 4-Mepy (2), have been investigated. These complexes have been characterized by elemental analyses, IR, UV-Vis and (1)H-NMR spectroscopy. The crystal structure of [Co{(BA)(2)pn}(py)(2)]ClO(4) (1) has been determined by X-ray diffraction. The coordination geometry around cobalt(III) is best described as a distorted octahedron. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Co(III)-Co(II) is electrochemically irreversible, which is accompanied by the dissociation of the axial N(py)-cobalt bonds. This process becomes quasi-reversible upon the addition of excess py ligands. The second reduction step of Co(II/I) shows reversible behavior and is not influenced by the nature of the axial ligands.

DOI： 10.1007/s11243-008-9127-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Several new mono- and dinuclear eta(5)-pentamethylcyclopentadienyl (Cp*) iridium(III) complexes bearing 5-methyltetrazolate (MeCN4-) have been synthesized and their molecular and crystal structures have been determined. For complexes incorporating 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen), both mononuclear kappa N-2-coordinated and dinuclear mu-kappa N-1:kappa N-3-bridging MeCN4 Complexes were obtained: [Cp*Ir(bpy or phen)(MeCN4-kappa N-2)]PF6 (1 or 3) and [{Cp*Ir(bpy or phen)}(2)(mu-MeCN4-kappa N-1:kappa N-3)](PF6)(3) (2 or 4), respectively. It was confirmed by X-ray analysis that the dinuclear complex in 2 has a characteristic structure with a pyramidal pocket constructed from a mu-kappa N-1:kappa N-3-bridging MeCN4- and two bpy ligands. In the case of analogous complexes with N,N-dimethyldithiocarbamate (Me(2)dtc(-)), yellow platelet crystals of mononuclear kappa N-1-coordinated complex, [Cp*Ir(Me(2)dtc)(MeCN4-kappa N-1)]center dot HN4CMe (5 center dot HN4CMe), and yellow prismatic crystals of dinuclear mu-kappa N-1:kappa N-4-bridging one, [{Cp*Ir(Me(2)dtc)}(2)(mu-MeCN4-kappa N-1: kappa N-4)]PF6 (6), were deposited. The kappa N-1- and kappa N-1:kappa N-4-bonding modes of MeCN4- in these complexes presumably arise from the compactness of the Me(2)dtc(-) coligand. 6 is the first example in which tetrazolates act as a mu-kappa N-1: kappa N-4-bridging ligand. Furthermore, the molecular and crystal structures of dinuclear complexes having mu-kappa S-2,N:kappa S-bridging 2-pyridinethiolate (2-Spy(-)) or 8-quinolinethiolate (8-Sqn(-)) ligands have been determined: [(Cp*Ir)(2)(mu-2-Spy or 8-Sqn-kappa S-2,N:kappa S)(2)] (7 or 8). These thiolato-bridging complexes were stable toward the addition of 5-methyltetrazole (HN4CMe), owing to the characteristic intramolecular stacking interaction between the pyridine or the quinoline rings. The 2-Spy complex of 7, however, reacted with an excess amount of Na(N4CMe), resulting in cleavage of the Ir-N(py) bond and coordination of MeCN4- in the mu-kappa N-2:kappa N-3-bridging mode: [(Cp*Ir)(2)(mu-2-Spy-kappa S:kappa S)(2)(mu-MeCN4-kappa N-2:kappa N-3)]PF6 (9). This bridging mode of MeCN4- was also observed in the triply bridging MeCN4 complex: [(Cp*Ir)(2)(mu-MeCN4-kappa N-2:kappa N-3)(3)]PF6 (10). In these various MeCN4 complexes, the structural parameters of the MeCN4 moiety were not perturbed by the difference in the bonding modes.

DOI： 10.1021/ic701631k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The crystal structures of mononuclear (azido)( pentamethylcyclopentadienyl) iridium(III) complexes bearing 2- or 8-quinolinethiolate (n-Sqn(-)), [Cp* Ir(N-3)( n-Sqn)] {n = 2 (1) or 8 ( 2); Cp* = eta(5)- C5Me5} have been determined by X-ray analysis. The 2-Sqn complex, 1, acquires severe steric strains in the four-membered kappa(2) N, S chelate ring, while the 8-Sqn isomer, 2, forms a strain-free five-membered planar kappa(2) N, S chelate ring. It has also been revealed that the corresponding benzimidazole-2-thiolate (Hbimt(-)) complex, which was obtained similarly to the above n-Sqn complexes from [Cp* Ir(N-3)(2)] (2) and Na(Hbimt), takes an unsymmetrical dinuclear structure bridged by two Hbimt(-) ligands with different bonding modes, [Cp* Ir(N-3){mu(S: N-1)-Hbimt}{mu(S:S)-Hbimt}Ir(N-3)Cp*] MeOH (3). (c) 2007 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.ica.2007.09.040

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The X-ray crystal structure of tetrakis (+)-hfbc Pr(III) complex, Na[Pr((+)-hfbc)(4)]center dot CH3CN, was compared with that of the corresponding Na-La complex with a pseudo-achiral dodecahedron, and the solution CD spectra were also discussed in the 4f-4f transition in consideration of the exciton CD couplet showing Delta-SAPR-8 configuration in CHCl3. (c) 2007 Published by Elsevier B.V.

DOI： 10.1016/j.jallcom.2007.04.236

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

In the title compound, [ Pt( C18H15N2) Cl], the Pt-II centre adopts a distorted square- planar coordination geometry due to the pincer- type monoanionic N - C - N tridentate ligand. The planar complexes stack via pi - pi interactions to form twodimensional accumulated sheets. This packing pattern is in contrast to that in related pincer- type N - C - N complexes, which exhibit a one- dimensional columnar stacking.

DOI： 10.1107/S0108270107044009

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DOI： 10.1107/S1600536807042493

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

DOI： 10.1107/S160053680704281X

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DOI： 10.1107/S160053680704559X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The magnetic interactions in a new series of isostructural imino nitroxide radical lanthanide(III) complexes, [Ln(hfac)(3)(IM2py)] (Ln = Gd-Yb: IM2py = 2-(2'-pyridyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazoline-l-oxy; hfac = 1, 1, 1, 5,5,5-hexafluoro-2,4-pentanedione), are examined by considering the intrinsic paramagnetic contribution of the Ln(III) ion from the corresponding [Ln(hfaC)3(pybzim)] with a diamagnetic pybzim(2-(2-pyridyl)benzimidazole) ligand; the Ln(III)-IM2py interaction being antiferromagnetic for the 4f(7) to 413 Ln(III) complexes and negligibly small for the other complexes. This series is the first example reverse to the previous cases for the series of Ln-Cu or Ln-aminoxyl(NIT) radical (4,5-dihydro-4,4,5,5-tetramethyl-IH-imidazoline-3-oxide-l-oxy) complexes, other than only a few examples of semiquinone Ln complexes. This reverse nature of the magnetic interaction, as compared with the NIT complexes, validates the empirical approach by O. Kahn et al. [Inorg. Chem. 38 (1999) 3692; J. Am. Chem. Soc. 122 (2000) 3413] in the spin-coupled systems for a series of Ln(III) complexes. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2007.02.024

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INT UNION CRYSTALLOGRAPHY  

The title compound, [IrBr2(eta(5)-C10H15)(C18H13P)]center dot CH2Cl2, is the first example of an iridium(III) phosphole complex to be characterized by X-ray crystallographic analysis. The Ir-P bond length is 2.2828 (15) angstrom, which is shorter by 0.04 angstrom than that of the analogous PPh3 complex. This is indicative of the steric compactness of 5-phenyldibenzophosphole compared with PPh3. The dibenzophosphole portion of the ligand is nearly planar, and the planes of the dibenzophosphole units of neighbouring molecules are stacked on top of each other to form a dimer in the crystal structure. The closest C center dot center dot center dot C distances between the planes are similar to 3.9 angstrom.

DOI： 10.1107/S1600536807026621

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A series of bis(4,4,4-trifluoro-1-R-1,3-butanedinato) Co(II) complexes with imino nitroxide radical(IM2py), [Co(RtfC)(2)(IM(2)py)] (R = trifluoromethyl, phenyl, naphthyl, thienyl), was prepared and characterized by the X-ray analysis which demonstrated the stereo-specific formation of the trans(CF3)-isomer with the trans disposition of the CF3 groups. The significant substituents effect on the UV-Vis spectra and magnetic properties were discussed in consideration of the inversion of the d pi(t(2g)) orbital levels leading to the orbital orthogonality or overlap with the SOMO pi* of IM2py in terms of the AOM parametrizations or spin-paring energy. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2006.09.054

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Several new cobalt(III) complexes containing (3-aminopropyl) dimethylphosphine (pdmp) have been prepared, and their molecular structures have been determined. A dichloro complex of trans(Cl,Cl)-cis(P,P)-[CoCl2(pdmp)(2)]PF6 (1) was prepared from trans-[CoCl2(py)(4)]Cl center dot 6H(2)O and pdmp. X-Ray crystallography confirmed the (C-2)-chair(2) conformation of two six-membered pdmp chelate rings in 1, while the analogous 1,3-bis(dimethylphosphino) propane (dmpp) complex trans-[CoCl2(dmpp)(2)]ClO4 (3) exhibited the (D-2d)-twist(2) conformation. Substitution reactions of 1 for ethane-1,2-diamine (en), pentane-2,4-dionate (acac), and N,N-dimethyldithiocarbamate (dtc) gave the mixed-ligand tris(chelate)-type complexes of [Co(en)(2)(pdmp)]Cl-2(PF6) (5), [Co(acac)(pdmp)(2)](PF6)(2) (7), and [Co(dtc)(3-n)(pdmp)(n)](PF6)(n) [n = 1 (9) or 2 (10)], respectively. The conformer of the complex cation in 5 was assigned as lel center dot ob center dot chair by X-ray analysis. In the case of the acac complex 7, both trans(P,N) (7a) and trans(N,N) (7b) isomers were isolated, and the complex cations were characterized as syn-chair(2) and anti-chair(2) conformers, respectively, with respect to the six-membered pdmp chelate rings. These conformers coincide with the most stable ones anticipated by the DFT optimum geometry calculations. In the crystal structure of trans(P,N)-[Co(dtc)(pdmp)(2)](BPh4)(2) (10') one of the pdmp chelate rings adopted a skew-boat (twist) conformation, which reduced the intramolecular steric ring-ring interaction effectively. The DFT optimized geometries for several isomers and/or conformers of [CoCl2(pdmp)(2)](+) were compared.

DOI： 10.1039/b612025c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A reaction of [Cp*lr(2-Spy)(N-3)] (Cp* = pentarnethylcyclopentadienyl; 2-Spy = 2-pyridinethiolate) with two equivalents of methyl iodide afforded the diiodo complex bearing 2-MeSpy, [Cp*lrl(2)(2-MeSpy)] (3). From X-ray crystallography and IR spectroscopy, the S atom of 2-MeSpy is coordinated to the metal ion in the solid state. In CD2Cl2, complex 3 exhibited a dissociation equilibrium of 2-MeSpy similar to the corresponding thioanisole complex of [Cp*lrl(2)(MeSPh)].

DOI： 10.1246/bcsj.79.1897

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

In the title compound, cis-[Pd(C5H14NP)(2)]Cl-2.CH4O, the coordination geometry around the Pd-II center is distorted square planar, with a cis-P2N2 configuration of the two chelating (3-amino-prop-yl)dimethyl-phosphine (pdmp) ligands. The six-membered pdmp chelate rings adopt chair conformations, and pairing of the chairs designates the complex cation as a (C-s)-chair(2) conformer. The distances between the Pd-II center and the Cl- anions are greater than 4.5 angstrom, indicating no obvious inter-action.

DOI： 10.1107/S0108270106023596

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

In the title compound, [Cu(NO3)(2)(C20H40N4)] center dot 3H(2)O, the Cu atom lies on a crystallographic inversion centre and has a distorted octahedral geometry, with four N atoms of the macrocyclic ligand in the equatorial positions and two O atoms of the axial nitrate ligands. The long axial Cu-O bond of 2.746 (2) angstrom may result from the Jahn-Teller effect. The macrocyclic ligand adopts the most stable trans-III configuration with the two six-membered rings in chair form and two five-membered rings in a gauche form.

DOI： 10.1007/S1600536806034234

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

For newly prepared sodium tetrakis( 3-heptafluorobutylryl-( +)-camphorato) Ln( III) complexes, the X-ray crystal analysis revealed an unprecedented pseudo-achiral dodecahedron ( DD-8 ( D-2d)), whereas in CHCl3 solution, the exciton CD and F-19 NMR spectra showed a novel chiral Delta-SAPR-8 ( C-4) configuration which is stereospecifically formed by a trapped Na+ ion with Na+center dot center dot center dot FC ( fluorocarbon) interactions.

DOI： 10.1021/ic0606633

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

In the monoclinic crystal structure of the title compound, trans-[ Ru( C3H5OS2)(2)( C18H15P)(2)] PF6 center dot H2O, the structure of the Ru-III complex cation is very similar to that in the orthorhombic crystal of the nonhydrated complex [ Noda, Ohuchi, Hashimoto, Fujiki, Itoh, Iwatsuki, Noda, Suzuki, Kashiwabara & Takagi ( 2006), Inorg. Chem. 45, 1349 - 1355]. In the present crystal structure, the P-Ru-P bond axes of the complex cations are aligned parallel to the [ 101] direction.

DOI： 10.1107/S1600536806013420

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A series of new iridium(III) complexes containing pentamethylcyclopentadienyl (Cp* = eta(5)-C5Me5) and 1,8-naphthyridine (napy) have been prepared. X-ray crystallography revealed that napy acted as a monodentate, a didentate chelating, and a bridging ligand in complexes of [Cp*IrCl2(napy)] (1), [Cp*IrCl(napy)]PF6 (2), and [(Cp*IrC])(2)(H)(napy)]PF6 (4), respectively. The crystal structure of [Cp*Ir(napy)(2)]-(PF6)(2) (3) has also been determined; the dicationic complex bore both monodentate and chelating napy ligands. Dinuclear Cp*Ir-III complex bridged by napy was only isolable if two Ir-III centers were supported by a hydride (H-) bridge. In complexes 2 and 3, the four-membered chelate rings formed by napy exhibited a large steric strain; in the rings the N-Ir-N bond angles were only 60.5(2)-61.0(4)degrees and the Ir-N-C angles were 94.7(8)-96.7(8)degrees. The bridging coordination of napy in complex 4 also afforded a large strain, i.e., the Ir-III centers were displaced by 0.84(3) angstrom from the napy plane, due to the steric interaction between two Cp*IrCl moieties. The monodentate napy complex I in CDCl3 or CD2Cl2 at ambient temperature showed a rapid coordination-site exchange reaction, which gave two N sites of napy equivalent; at temperatures below -40 degrees C, the H-1 NMR spectra corresponded to the molecular structure of [Cp*IrCl2(napy-KN)]. The analogous diazido complex of [Cp*Ir(N-3)(2)(napy)] (5) has also been prepared, and the crystal structure has been determined. In contrast to the dichloro complex 1, the diazido complex 5 exhibited a dissociation equilibrium of coordinated napy in solution. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2006.02.033

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Controlled-potential electrochemical oxidation of cis-[Ru(ROCS2)(2)(PPh3)(2)] (R = Et, Pr-i) yielded corresponding Ru(III) complexes, and the crystal structures of cis-[Ru(ROCS2)(2)(PPh3)(2)] and trans-[Ru(ROCS2)(2)(PPh3)(2)](PF6) were determined. Both pairs of complexes exhibited almost identical coordination structures. The Ru-P distances in trans-[Ru-III(ROCS2)(2)(PPh3)(2)](PF6) [2.436(3)-2.443(3) angstrom] were significantly longer than those in cis-[Ru-II(ROCS2)(2)(PPh3)(2)] [2.306(1)-2.315(2) angstrom]: the smaller ionic radius of Ru(III) than that of Ru(II) stabilizes the trans conformation for the Ru(III) complex due to the steric requirement of bulky phosphine ligands while mutual trans influence by the phosphine ligands induces significant elongation of the Ru-III-P bonds. Cyclic voltammograms of the cis-[Ru(ROCS2)(2)(PPh3)(2)] and trans-[Ru(ROCS2)(2)(PPh3)(2)](+) Complexes in dichloromethane solution exhibited typical dual redox signals corresponding to the cis-[Ru(ROCS2)(2)(PPh3)(2)](+/0) (ca. +0.15 and +0.10 V vs ferrocenium/ferrocene couple for R = Et and Pr-i, respectively) and to trans-[Ru(ROCS2)(2)(PPh3)(2)](+/0) (-0.05 and -0.15 V vs ferrocenium/ferrocene for R = Et and Pr-i, respectively) couples. Analyses on the basis of the Nicholson and Shain's method revealed that the thermal disappearance rate of transient trans-[Ru(ROCS2)(2)(PPh3)(2)] was dependent on the concentration of PPh3 in the bulk: the rate constant for the intramolecular isomerization reaction of trans-[Ru((PrOCS2)-Pr-i)(2)(PPh3)(2)] was determined as 0.338 +/- 0.004 s(-1) at 298.3 K (Delta H* = 41.8 +/- 1.5 kJ mol(-1) and Delta S* = -114 +/- J mol(-1) K-1), while the dissociation rate constant of coordinated PPh3 from the trans-[Ru((PrOCS2)-Pr-i)(2)(PPh3)(2)] species was estimated as 0.113 +/- 0.008 s(-1) at 298.3 K (Delta H* = 97.6 +/- 0.8 kJ mol(-1) and Delta S* = 64 +/- 3 J mol(-1) K-1), by monitoring the EC reaction (electrode reaction followed by chemical processes) at different concentrations of PPh3 in the bulk. It was found that the trans to cis isomerization reaction takes place via the partial dissociation of (PrOCS2-)-Pr-i from Ru(II), contrary to the previous claim that it takes place by the twist mechanism.

DOI： 10.1021/ic0514871

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The synthesis and magnetic characterization of pyrazolato-bridged dinuclear complexes [{M(NCS)(4-Phpy)}(2)(mu-bpypz)(2)] (Hbpypz=3,5-bis(2-pyridyl)-pyrazole; 4-Phpy=4-phenylpyridine; M=CO2+ (1) and Fe2+ (2)) are described together with the X-ray crystal analysis of the cobalt complex. The structure of 1 shows that the desired coordination has been achieved with the cobalt atoms being coordinated to two bpypz to form the dimer. The X-ray diffraction patterns show 1 and 2 to be isomorphous at room temperature. 2 displays it single spin-crossover transition between the [HS-HS] and [LS-LS] states with T-c = 150 K. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2005.03.047

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Photolysis of the (azido)(pyrdine-2-thiolato)iridium(III) complex Cp*lr(2-Spy)(N-3) (1) gave a pyridine-1-imido-2-thiolato complex, Cp*lr(1-N-2-Spy) (2), in which one of the nitrogen atoms of the azide ligand has been inserted into the lr-N(py) bond (Cp* = eta(5)-C5Me5). Complex 2 reacted quantitatively with methyl iodide to give the N-methylated product, [Cp*lr(1-NMe-2-Spy)]l (3). X-ray crystallography revealed that both 2 and 3 have similar two-legged piano stool structures with planar 1-N-2-Spy(2-) or 1-NMe-2(-)Spyligands, which form iridacyclopentadienyl-like rings by moderate S(p pi)/N(p pi) to lr(d pi) pi donation.

DOI： 10.1021/ic051097z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Cobalt(III) and rhodium(III) complexes of the series of [(MCl3)-Cl-III - (P)(3) + n](n+) (M = Co or Rh; n = 0, 1, 2 or 3) have been prepared with the use of 1,1,1-tris(dimethylphosphinomethyl)ethane (tdmme) and mono- or didentate phosphines. The single-crystal X-ray analyses of both series of complexes revealed that the M-P and M-Cl bond lengths were dependent primarily on the strong trans influence of the phosphines, and secondarily on the steric congestion around the metal center resulting from the coordination of several phosphine groups. In fact, the M-P(tdmme) bonds became longer in the order Of [MCl3(tdmme)] &lt; [MCl2(tdmme)(PMe3)](+) &lt; [MCI(tdmme)(dmpe)](2+) (dmpe = 1,2-bis(dimethylphosphino)ethane) &lt; [M(tdmme)(2)](3+) for both Co-III and Rh-III series of complexes, while the M-CI bond lengths were shortened in this order (except for [M(tdmme)(2)](3+)). Such a steric congestion around the metal center can also account for the structural and spectroscopic characteristics of the series of complexes, [MCI(tdmme)(dmpm, dmpe or dmpp)](2+) (dmpm = bis(dimethylphosphino)methane, dmpp = 1,3-bis(dimethylphosphino)propane). The X-ray analysis for [CoCl(tdmme)(dmpm or dmpe)](BF4)(2) showed that all Co-P bonds in the dmpm complex were shorter by 0.03-0.04 angstrom than those in the dmpe complex. Furthermore, the first d-d transition energy of the Co-III complexes and the (1)J(Rh-P(tdmme)) coupling constants observed for the Rh-III complexes indicated an unusual order in the coordination bond strengths of the didentate diphosphines, i.e., dmpm &gt; dmpe &gt; dmpp. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2005.02.008

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Synthesis, characterization and magnetic properties of new lanthanide-radical complexes, [Ln(III)(hfac)(3)(IM2imH)] (Ln = Gd, Tb; IM2imH=2-(2-pyridyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazolyl-1-oxy), are described. The molecular structure of the [Tb(hfaC)(3)(IM2imH)] has been determined by the X-ray diffraction. The magnetic susceptibility data for [Gd(hfaC)(3)(IM2imH)] show that the Gd-IM2imH magnetic interaction is antiferromagnetic with an exchange coupling constant J = -2.59 cm(-1) in contrast to the ferromagnetic interaction in most of Gd(III) complexes containing paramagnetic center, which will be examined in connection with planarity of the IM2imH chelate. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2004.11.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL MUNKSGAARD  

In the title compound, [Ir(C10H15)(N-3)(C10H8N2)]PF6, the linear azide ligand adopts an end-on terminal coordination mode with a relatively long Ir-N bond of 2.230 (6) Angstrom. The azide is asymmetric in an unusual way: the azide N-N bond adjacent to the azide Ir-N bond [1.025 (12) Angstrom] is significantly shorter than the terminal azide N-N bond [1.282 (15) Angstrom], while the azide Ir-N-N bond angle is 116.4 (6)degrees.

DOI： 10.1107/S1600536805003727

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

[Cu(2,9-dimethyl-1,10-phenanthroline)2](2+) and [Cu(6,6'-dimethyl-2,2'-bipyridine)(2)](2+/+) complexes with no coordinated solvent molecule were synthesized and the crystal structures were analyzed: the coordination geometry around the Cu(I) center was in the D-2d symmetry while a D-2 structure was observed for the four-coordinate Cu(II) complexes. Coordination of a water or an acetonitrile molecule was found in the trigonal plane of the five-coordinate Cu(II) complex in the Tbp (trigonal bipyramidal) structure. Spectrophotometric analyses revealed that the D-2 structure of the Cu(II) complex was retained in nitromethane, although a five-coordinate Tbp species (green in color), was readily formed upon dissolution of the solid (reddish brown) in acetonitrile. The electron self-exchange reaction between D-2d-Cu(I) and D-2-Cu(II), observed by the NMR method, was very rapid with k(ex) = (1.1 +/- 0.2) x 10(5) kg mol(-1) s(-1) at 25degreesC(DeltaH* = 15.6 +/- 1.3 kJ mol(-1) and DeltaS* = 96 +/- 4 J mol(-1) K-1), which was more than 10 times larger than that reported for the self-exchange reaction between D-2d-Cu(I) and Tbp-Cu(II) in acetonitrile. The cross reduction reactions of D-2-Cu(II) by ferrocene and decamethylferrocene in nitromethane exhibited a completely gated behavior, while the oxidation reaction of D-2d-Cu(I) by [Ni(1,4,7-triazacyclononane)(2)](3+) in nitromethane estimated an identically large self-exchange rate constant to that directly obtained by the NMR method. The electron self-exchange rate constant estimated from the oxidation cross reaction in 50% v/v acetonitrile nitromethane mixture was 10 times smaller than that observed in pure nitromethane. On the basis of the Principle of the Least Motion (PLM) and the Symmetry Rules, it was concluded that gated behaviors observed for the reduction reactions of the five-coordinate Cu(II) polypyridine complexes are related to the high-energy C-2v --&gt; D-2d conformational change around Cu(II), and that the electron self-exchange reactions of the Cu(II)/(I) couples are always adiabatic through the C-2v structures for both Cu(II) and Cu(I) since the conformational changes between D-2d, D-2 and C-2v structures for Cu(I) as well as the conformational change between Tbp and C-2v structures for Cu(II) are symmetry-allowed. The completely gated behavior observed for the reduction reactions of D-2-Cu(II) species in nitromethane was attributed to the very slow conformational change from the ground-state D-2 to the entatic D-2d structure that is symmetry-forbidden for d(9) metal complexes: the very slow back reaction, the forbidden conformational change from entatic to the ground-state D-2 structure, ensures that the rate of the reduction reaction is independent of the concentration of the reducing reagent.

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A reaction of the triple cubane-type organometallic polyoxomolybdate cluster, [(Cp * Rh)4Mo4O16] · 2H2O (1 · 2H2O), with 1,2-benzenedithiol gives a 1,2-benzenedithiolate-bridged dinuclear complex, [(Cp * Rh)2(μ(S)-1,2-C6H4S2-S,S′)2] (2), and another dinuclear complex, [(Cp * Rh)2(μ(S)-1,2-C6H4S2-S,S′)(μ(S)-1,2-C6H4S(SO2)-S,S′)] (3), both of which are characterized by the single-crystal X-ray diffraction method. The former complex, 2, is also obtained from a reaction of [(Cp * RhCl)2(μ-Cl)2] with 1,2-benzenedithiol in the presence of NaOCH3, and the latter, 3, from oxygenation of 2 with t-BuOOH. The 1H NMR study in CD2Cl2 indicates that complex 2 changes gradually to a coordinatively unsaturated mononuclear complex, [Cp * Rh(1,2-C6H4S2-S,S′)] (4). An analogous mononuclear iridium(III) complex, [Cp * Ir(1,2-C6H4S2-S,S′)] (5), is also prepared and characterized by X-ray structural analysis. © 1997 Elsevier Science S.A.

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DOI： 10.1246/cl.1996.911

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DOI： 10.1039/dt9960003779

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

A new phosphine ligand, 8-(dimethylphosphino)quinoline (Me₂Pqn), and its palladium(I or II) complexes, [PdX₂(Me₂Pqn)] (X = Cl (1a), Br (1b), and I (1c)), [Pd(Me₂Pqn)₂](BF₄)₂ (2b), and [Pd₂Cl₂(Me₂Pqn)₂] (3), have been prepared and characterized. The structures of 2b and 3 have been determined by X-ray analysis. The crystal data and final R values are: for 2b, FW = 658.42, monoclinic, P2₁/n, a = 17.453(2), b = 10.453(2), c = 14.928(2) Å, β = 105.63(1)°, V = 2622.8(5) ų, D_x = 1.667 Mg m⁻³, and Z = 4, R = 0.071 for 3908 reflections (|F_o| ≥ 3σ(|F_o|)); for 3, MW = 662.64, monoclinic, P2₁/n, a = 16.429(1), b = 12.191(1), c = 12.821(1) Å, β = 92.673(8)°, V = 2565.1(4) ų, D_x = 1.714 Mg m⁻³, and Z = 4, R = 0.056 for 5136 reflections (|F_o| ≥ 3σ(|F_o|)). In 2b the square coordination plane formed by two long Pd–N (2.138(9) and 2.135(8) Å) and two Pd–P bonds (2.243(3) and 2.237(3) Å) is slightly distorted towards tetrahedral geometry, the dihedral angle between the two chelate planes formed by the Pd, P, and N atoms being 10.3(2)°. 3 is a dinuclear complex with a Pd–Pd bond (2.542(1) Å), Me₂Pqn chelates to one Pd(I) center, and the N donor atom occupies the trans position to the Pd–Pd bond. The dihedral angle between the two coordination planes linked by the Pd–Pd bond is nearly a right angle, 82.13(6)°.

DOI： 10.1246/bcsj.68.1619

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DOI： 10.1016/0957-4166(95)00142-C

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DOI： 10.1021/ic00110a003

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DOI： 10.1021/ic00107a002

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Publishing type：Research paper (scientific journal)  

DOI： 10.1039/dt9950003609

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Publishing type：Research paper (scientific journal)  

DOI： 10.1007/BF01165471

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A heterotrimetallic sulfide cluster with an organometallic group, [Cp*Rh{P(OEt)(3)}(mu-S)(2)W(mu-S)2CuCl] (Cp*=eta(5)-C(5)Me(5)), was prepared stepwise by using mononuclear units of organorhodium(III), thiotungstate(VI), and chlorocopper(I). X-ray crystal structure analysis revealed that the cluster possesses a linear sequence of middle (Rh), early (W), and late (Cu) transition metal atoms with octahedral, tetrahedral, and trigonal planar coordination geometries, respectively.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

The title complex, prepared from a reaction of [(IrCp^*Cl)₂(μ-Cl)₂] with K₂CrO₄ in water, has been characterized via a single-crystal X-ray diffraction study. In the solid state the tri-μ-hydroxo-diiridium complex cations, the dichromates having the staggered conformation, and the water molecules of crystallization are entirely connected by hydrogen bonds forming a novel two-dimensional layer structure.

DOI： 10.1246/bcsj.67.1968

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

The iridium(III) complexes containing (2-aminoethyl)dimethylphosphine (edmp) or (2-aminoethyl)diphenylphosphine (edpp) were prepared. Crystal structures of fac-[Ir(edmp)₃]Cl₃·5H₂O (2), trans(Cl,Cl),cis(P,P)-[IrCl₂(edpp)₂]BF₄ (3), and Δ(lel₃)- and Λ(ob₃)-[Ir(R,R-chxn)₃](NO₃)₃·3H₂O (4 and 5; chxn = trans-1,2-cyclohexanediamine) were determined by single-crystal X-ray diffraction. Crystal data and final R values are: for 2, FW = 703.7, triclinic, <sub></SUB>, a = 11.718(2), b = 13.199(1), c = 9.482(1) Å, α = 91.44(1), β = 105.86(1), γ = 90.53(1)°, V = 1410.0(2) ų, Dx = 1.66 Mg m⁻³, and Z = 2, R = 0.039 for 5410 reflections. For 3, FW = 808.5, triclinic, , a = 11.465(1), b = 13.694(1), c = 10.049(1) Å, α = 94.764(6), β = 92.197(8), γ = 102.807(8)°, V = 1530.5(2) ų, Dx = 1.75 Mg m⁻³, and Z = 2, R = 0.035 for 5978 reflections. For 4, FW = 774.9, hexagonal, P63, a = 13.005(1), c = 10.221(2) Å, V = 1497.1(3) ų, Dm = 1.71(2), Dx = 1.72 Mg m⁻³, and Z = 2, R = 0.020 for 1063 reflections. For 5, hexagonal, FW = 774.9, P63, a = 13.359(1), c = 9.848(2) Å, V = 1522.0(3) ų, Dm = 1.70(2), Dx = 1.69Mg m⁻³, and Z = 2, R = 0.015 for 1105 reflections. The average Ir–N bond length of 2.167(6) Å in 2 is longer by 0.077(6) Å than those in 4 and 5. The structural data of the corresponding cobalt(III) and rhodium(III) complexes show that the order of the strength of the trans influence of the –PMe2 group in edmp is Co^III < Ir^III < Rh^III. In 3, the elongation of the metal–nitrogen bond length by the trans influence of the –PPh2 group in edpp is smaller than that of the –PMe2 group in 2, and the elongation is nearly the same as those in the corresponding cobalt(III) and rhodium(III) complexes. The absorption spectra of the two series of complexes, fac-[M(edmp)3]³⁺ and trans(Cl,Cl),cis(P,P)-[MCl2(edpp)₂]⁺ (M = Co^III, Rh^III, and Ir^III) are compared and Shimura's spectrochemical parameters for iridium(III) are discussed.

DOI： 10.1246/bcsj.67.1013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

Crystal structures of Pd(I) and Pt(I) dinuclear complexes, [MM′Cl₂(μ-Me₂Ppy)₂] (MM′ = Pd₂ (1), PdPt (2), and Pt₂ (3)) and [Pd₂Cl₂(μ-Ph₂Ppy)₂] (4), were determined by the single crystal X-ray diffraction method. Crystal data and final R values are: 1, triclinic, _{</SUB>, a = 10.019(2), b = 10.902(2), c = 9.062(1) Å, α = 97.75(2), β = 102.45(2), γ = 82.64(2)°, V = 952.7(3) ų, Z = 2, and R = 0.047; 2, monoclinic, P21/n, a = 16.532(2), b = 19.205(3), c = 13.260(2) Å, β = 93.86(2)°, V = 4200(1) ų, Z = 8, and R = 0.043; 3, monoclinic, P21/n, a = 16.515(5), b = 19.095(10), c = 13.233(4) Å, β = 93.15(3)°, V = 4167(3) ų, Z = 8, and R = 0.047; 4, monoclinic, C2/c, a = 30.505(4), b = 17.896(2), c = 12.983(1) Å, β = 98.52(1)°, V = 7009(1) ų, Z = 8, and R = 0.041. All of the complexes were found to be the head-to-tail isomer of a side-by-side type dinuclear structure. The metal–metal bond distances of 2.584(1) Å in 1, 2.561(1) Å in 2, 2.573(1) Å in 3, and 2.594(1) Å in 4 are relatively short compared with those in the analogous dinuclear complexes bridged by diphosphine ligands. All of the M–P, M–N, and M–Cl distances in Me2Ppy complexes become shortened in the order of the Pd2 > PdPt > Pt<SUB>2} complexes.

DOI： 10.1246/bcsj.65.1817

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DOI： 10.1246/bcsj.65.1016

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DOI： 10.1246/cl.1992.1067

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

The complexes [MX₂(PMe₂py-P)₂] (M=Pd(II), Pt(II); X=Cl, Br, and I) have been synthesized and characterized both in the solid state and in solution by their infrared and ¹H, ¹³C, and ³¹P NMR spectra, in addition to an X-ray crystallographic analysis of cis-[PdCl₂(PMe₂py-P)₂]. The latter complex exists as a cis–trans equilibrium mixture in solution, while only the cis isomer has been isolated in the solid state. The [PdBr₂(PMe₂py-P)₂] complex which has been isolated as the trans isomer shows also the same isomerization in solution, in contrast to [PdBr₂(PMe₂Ph)₂] which exists only as the trans isomer both in the solid state and in solution. Furthermore, PMe₂py has been found to have the ability for chelation via the nitrogen and phosphorus atoms to make a four-membered chelate ring. The chelate ring in the complexes [PdX(PMe₂py)₂]Y (X=Cl, Br, and I; Y=ClO₄⁻, PF₆⁻) has been confirmed by infrared spectra and X-ray analysis of cis(P,P)-[PdCl(PMe₂py-P,N)(PMe₂py-P)]ClO₄. This is the first example in which PMe₂py is acting as a chelating ligand.

DOI： 10.1246/bcsj.63.3434

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Event date： 2020.3.22 - 2020.3.25

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Event date： 2020.3.22 - 2020.3.25

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Event date： 2019.11.16 - 2019.11.17

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Venue：徳島  

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Event date： 2019.11.16 - 2019.11.17

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Event date： 2019.9.21 - 2019.9.23

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Venue：名古屋  

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Event date： 2019.9.21 - 2019.9.23

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Venue：名古屋  

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Venue：名古屋  

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Venue：名古屋  

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Event date： 2019.9.21 - 2019.9.23

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Event date： 2018.11.17 - 2018.11.18

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Venue：松山  

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Venue：松山  

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Event date： 2018.7.30 - 2018.8.4

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Venue：Sendai, Japan  

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Venue：Sendai, Japan  

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Venue：Sendai, Japan  

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Venue：Sendai, Japan  

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Venue：Sendai, Japan  

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Event date： 2018.7.28 - 2018.7.30

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Venue：仙台  

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Event date： 2018.3.20 - 2018.3.23

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Venue：船橋  

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Event date： 2018.3.20 - 2018.3.22

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Venue：Nanyang Technological University, Singapore  

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Event date： 2017.12.15

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Venue：Toyonaka, Osaka  

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Venue：札幌  

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Venue：札幌  

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Venue：札幌  

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Venue：札幌  

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Venue：札幌  

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Venue：札幌  

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Venue：札幌  

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Event date： 2017.9.16 - 2017.9.18

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Venue：札幌  

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Event date： 2017.9.16 - 2017.9.18

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Venue：札幌  

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Venue：札幌  

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Event date： 2017.9.16 - 2017.9.18

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Venue：札幌  

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Event date： 2017.7.2 - 2017.7.5

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Venue：Copenhagen, Denmark  

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Venue：横浜  

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Venue：Karpacz, Poland  

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Venue：Karpacz, Poland  

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Venue：Karpacz, Poland  

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Venue：岡山  

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Venue：岡山  

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Venue：岡山  

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Event date： 2016.11.5 - 2016.11.6

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Venue：高松  

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Venue：高松  

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Venue：高松  

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Venue：高松  

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Event date： 2016.9.10 - 2016.9.12

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

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Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

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Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

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Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡  

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Event date： 2016.9.10 - 2016.9.12

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡  

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Event date： 2016.7.4 - 2016.7.8

Language：English   Presentation type：Poster presentation  

Venue：Brest, France  

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Event date： 2016.7.4 - 2016.7.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Brest, France  

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Event date： 2016.7.4 - 2016.7.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Brest, France  

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Event date： 2016.7.4 - 2016.7.8

Language：English   Presentation type：Poster presentation  

Venue：Brest, France  

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Event date： 2016.7.4

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Toulouse, France  

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Event date： 2016.3.25 - 2016.3.28

Language：English   Presentation type：Oral presentation (general)  

Venue：京田辺  

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Event date： 2016.3.25 - 2016.3.28

Language：Japanese   Presentation type：Poster presentation  

Venue：京田辺  

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Event date： 2016.3.25 - 2016.3.28

Language：Japanese   Presentation type：Poster presentation  

Venue：京田辺  

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