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

A mixture of 2-pyridine carboxaldehyde, 4-formylimidazole (or 2-methyl-4-formylimidazole), and NiCl2 center dot 6H(2)O in a molar ratio of 2:2:1 was reacted with two equivalents of hydrazine monohydrate in methanol, followed by the addition of aqueous NH4PF6 solution, afforded a Ni-II complex with two unsymmetric azine-based ligands, [Ni(HLH)(2)](PF6)(2) (1) or [Ni(HLMe)(2)](PF6)(2) (2), in a high yield, where HLH denotes 2-pyridylmethylidenehydrazono-(4-imidazolyl)methane and HLMe is its 2-methyl-4-imidazolyl derivative. The spectroscopic measurements and elemental analysis confirmed the phase purity of the bulk products, and the single-crystal X-ray analysis revealed the molecular and crystal structures of the Ni-II complexes bearing an unsymmetric HLH or HLMe azines in a tridentate kappa(3) N, N', N" coordination mode. The HLH complex with a methanol solvent, 1 center dot MeOH, crystallizes in the orthorhombic non-centrosymmetric space group P2(1)2(1)2(1) with Z = 4, affording conglomerate crystals, while the HLMe complex, 2 center dot H2O center dot Et2O, crystallizes in the monoclinic and centrosymmetric space group P2(1)/n with Z = 4. In the crystal of 2 center dot H2O center dot Et2O, there is intermolecular hydrogen-bonding interaction between the imidazole N-H and the neighboring uncoordinated azine-N atom, forming a one-dimensional polymeric structure, but there is no obvious magnetic interaction among the intra- and interchain paramagnetic Ni-II ions.

DOI： 10.3390/molecules27206788

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The compound crystallized in a monoclinic system, and was characterized thus: space group P2(1)ln, a = 7.887(41)angstrom, b = 21.853(11)angstrom, c = 14.355(7)angstrom, beta = 100.567(4)degrees, Z = 4, V = 2432.27(28)angstrom(3). The crystal structure was solved by direct methods and refined by full-matrix least squares on F-2 to final values of R-1 = 0.0539 and wR(2) = 0.1568. 1,3-Diyne of the title compound, undergoing C-C bond coupling with carbon monoxide, cross-links to {(eta(5)-Cp)(2)Fe-2(mu-CO) (CO)(2)}-group to form a 1,2-dimetalla-3-cyclopentene-5-one by a {mu, eta(1): eta(1): eta(2))-bond fashion with atomic distances of Fe1-Fe2 2.553(1)angstrom, Fe1-C1 2.058(3)angstrom, Fe2-C2 1.945(3)angstrom, C1-C2 1.423(4)angstrom, and C1-C3 1.499(4)angstrom, respectively.

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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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

Total synthesis of nilotinin M3, which is a member of the ellagitannin family of natural products containing an isodehydrodigalloyl (isoDHDG) group, was achieved using the Ullmann reaction to construct a highly functionalized diaryl ether.

DOI： 10.1055/a-1508-9541

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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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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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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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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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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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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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DOI： 10.1039/c9dt03007g

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DOI： 10.1039/c8dt04537b

PubMed

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

DOI： 10.1107/S2414314618014827

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

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 Mn-II and Co-II salts, the M-II ion is oxidized by air to form a cationic complex with two mono-deprotonated ligands, [M-III(S-HLMe)(2)]X [M, X = Mn, ClO4 (S-1ClO(4)); Co, ClO4 (S-3ClO(4)); and Co, Cl (S-3Cl)], where (S-HLMe)(-) is coordinated to a M-III center in a tridentate O-3,N,N mode with a mer configuration. In contrast, the Ni-II ion is not oxidized; only one of the ligands is deprotonated to form a similar monocationic complex, [Ni-II(S-HLMe)(S-H2LMe)]PF6 (S-6PF(6)), 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 Ni-II complexes of [Ni(HLMe)(H2LMe)](PF6 or Cl) (rac-6PF(6) 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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Two polymorphs of iron(II) complex fac-[Fe-II(HLn-Pr)(3)]Cl.PF6, 1 and 2, were obtained (HLn-Pr = 2-methylimidazole-4-yl-methylideneamino-n-propyl ligand). Complex cations, fac-[Fe-II(HLn-Pr)(3)](2+), of 1 and 2 had similar octahedral and facial geometries coordinated with three bidentate HLn-Pr ligands. The three imidazole groups in fac-[Fe-II(HLn-Pr)(3)](2+) with Delta- and Lambda-enantiomorphs are hydrogen-bonded with three Cl- ions, forming one-dimensional (1D) and two-dimensional (2D) network structures in 1 and 2, respectively. Complex 1 had a ladder-like 1D structure formed by imidazole...chloride hydrogen bonds, with a circular binuclear net unit of {...fac-[Fe-II(HLn-Pr)(3)](2+)...Cl-...}(2), and showed two successive scan rate dependent spin crossover (SCO) processes with thermal hysteresis. Complex 2 had a 2D network structure formed by imidazole...chloride hydrogen bonds with circular binuclear and tetranuclear net units of {...fac-[Fe-II(HLn-Pr)(3)](2+)...Cl-...}(2),(4), and showed a one-step scan rate dependent SCO profile centered at 143 K with thermal hysteresis. The relaxation property was identified from the scan rate dependence of magnetic susceptibility and temperature dependent Mossbauer spectra and X-ray diffraction studies. The crystal structure of 2 was analyzed at 12 temperatures in a cooling cycle. Upon lowering the temperature, the crystal system transformed from a monoclinic to a triclinic lattice at 210 K in a high-spin state, and then transformed to a low-spin state at 150 K in the triclinic system. (c) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2017.03.028

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The 1:1 assembly reaction of the racemic form of the crosslinking ligand complex Na[(CuLdpen)-L-II(1R2R/1S2S)] with Ln(III)(NO3)36H2O gave the centrosymmetric circular (Cu(II)Ln(III))(2) complex [(CuLdpen)-L-II(1R2R/1S2S)Ln(III)(NO3)2]2 (1Ln: Ln = Gd, Tb, Dy), while the reaction of the enantiopure form Na[(CuLdpen(1R2R))-L-II] with Ln(III)(NO3)36H2O gave the chiral chainlike (Cu(II)Ln(III))(1)8 complex [Cu(II)L(dpen(1R2R))Ln(III)(NO3)2(CH3CN)]18CH3CN (2Ln: Ln = Gd, Tb, Dy), where {(CuLdpen(1R2R))-L-II is (N((1R,2R)2(((E)3ethoxy2oxybenzylidene)amino)1,2diphenylethyl)2oxybenzamide)copper(II) and {(CuLdpen)-L-II(1R2R/1S2S) is the racemic mixture of {(CuLdpen(1R2R))-L-II and {(CuLdpen)-L-II(1S2S). The copper(II) component functions as a crosslinking ligand complex and bridges two Ln(III) ions at two phenoxo oxygen atoms and one ethoxy oxygen atom, as well as at an amido oxygen atom. For 1Ln, two binuclear species of [Cu(II)L(dpen(1R2R))Ln(III)(NO3)(2)] and [(CuLdpen)-L-II(1S2S)Ln(III)(NO3)(2)] with opposite chiralities are linked by two amido oxygen atoms O3 and O3* to form a centrosymmetric circular structure with GdCu = 3.370(1) A and GdCu* = 5.627(1) A. For 2Ln, binuclear species with the same chirality are bridged by GdO3* = 2.228(5) A to form a chiral chainlike structure with GdCu = 3.3348(9) A and GdCu* = 6.2326(9) A. The bridged angles through the amido group of GdO3*C7* are 133.9(5) and 177.6(4) for 1Gd and 2Gd, respectively. The magnetic susceptibilities of 1Gd and 2Gd were analyzed by the spinonly Hamiltonian on the basis of the circular tetranuclear ((CuGdIII)-Gd-II)(2) and linear chainlike ((CuGdIII)-Gd-II)(1)8 structures, respectively. The (CuGdIII)-Gd-II magnetic interactions through two phenoxo bridges and a threeatom NCO bridge, J(1) and J(2), are both ferromagnetic to be J1 = +4.6 cm(1) and J(2) = +1.8 cm(1) for 1Gd and J(1) = +4.2 cm(1) and J(2) = +0.037 cm(1) for 2Gd. The J(2) value of 2Gd is much smaller than that of 1Gd. When the temperature was lowered, 1Ln and 2Ln (Ln = Tb, Dy) showed a decrease in the Delta MT vs T plot due to crystal field effects on the Ln(III) ion (Stark splitting) and an increase due to the ferromagnetic Cu(II)Ln(III) interaction. The magnetization values of 1Ln and 2Ln (Ln = Tb, Dy) without liquid paraffin are considerably larger than the corresponding values with liquid paraffin, indicating the presence of strong magnetic anisotropy. 1Tb and 1Dy showed frequency dependence of ac magnetic susceptibility under zero external dc magnetic field, showing the behavior of singlemolecule magnets (SMMs). 2Tb and 2Dy showed no frequency dependence under a zero external magnetic field but showed a meaningful frequency dependence under an external magnetic field. Their energy barriers, Delta/k(B), estimated by the Arrhenius plots are 29.4(6) and 20.6(3) K for 1Tb and 2Tb under dc bias fields of 0 and 1000 Oe, respectively, and those of 1Dy and 2Dy are 13.1(9) K and 16.4(2) K under dc bias fields of 0 and 1000 Oe, respectively.

DOI： 10.1021/acs.inorgchem.6b02668

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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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Two Dym complexes with same N603 donor atoms but different donor atom arrangements 'fac'-[Dy-III(HLDL-ala)(3)]center dot 8H(2)O (1) and 'mer'-[Dy-III(HLDL-phe)(3)]center dot 7H(2)O (2) were synthesized, where H2LDL-ala and H2LDL-phe are tridentate NNO ligands of N-Rimidazol-4-yl)methylidene]-DL-alanine and N-[(imidazol-4-yl)methylidene]-DL-phenylalanine, respectively. Each Dy-III ion is coordinated by three mono-deprotonated mono-negative NNO tridentate ligands to form a nona-coordination geometry of a tricapped trigonal prism (TTP). 1 consists of enantiomers 'fac'-[Dy-III(HLD-ala)(3)], and 'fac'-[Dy-III(HLL-ala)(3)], while 2 consists of 'mer'-[Dy-III(HLD-phe)(2)(HLL-phe)] and 'mer'-[Dy-III(HLD-phe)(HLL-ala)(2)]. The temperature dependence of the magnetic susceptibilities and field-dependence of the magnetization of two complexes showed the different magnetic profiles and the Stark splitting of the ground state H-6(15/2) due to the crystal field effect on Dy-III ion (4f(9), J = 15/2, S = 5/2, L = 5, g(J) = 4/3, H-6(15/2)). Luminescence spectra were observed and the fine structures assigned to the F-4(9/2) -> H-6(15/2) transitions are partially observed. 1 and 2 showed an out-of phase signal with frequency-dependence in alternating current (ac) susceptibility under a dc bias field of 1000 Oe, indicative of field induced single ion magnet (SIM). The ac magnetic susceptibilities under 1000 Oe dc field of 2 showed the maximum peaks at the higher temperature than those of 1, indicating that the energy barrier of 2 is larger than that of 1. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2016.01.048

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A binuclear tetra-acetate bridged Gd-III complex [Gd-2(mu(2)-O2CMe)(4)(H2L)(2)](ClO4)(2)center dot 2H(2)O center dot 2MeOH was synthesized, where H2L = bis(5-methylimidazol-4-yl-methylideneaminopropyl)methylamine. The linear polydentate ligand H2L functions as a binding group to two Gd-III ions. Two Gd-III ions are bridged by two acetate in eta(1):eta(1):mu(2) fashion and other two in eta(2):eta(1):mu(2) fashion. The Gd-III center dot center dot center dot Gd-III distance of 3.920 (6) angstrom is shorter than 4.183(1) angstrom of the bis-acetate bridged Gd-III complex [{Gd-III(O2CMe)(3)(H2O)(2)}(2)]center dot 4H(2)O. A weak anti-ferromagnetic Gd-III-Gd-III interaction was observed. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2015.12.029

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A SCO iron(III) complex [Fe-III(Him)(2)(4MeOhapen)]CF3SO3 was synthesized, where Him = imidazole and 4-MeOhapen = N,N'-bis(2-oxy-4-methoxyacetophenylidene)ethylenediamine. Fe-III ion has an octahedral coordination geometry with N2O2 donor atoms of the equatorial tetradentate ligand (4-MeOhapen) and two nitrogen atoms of two imidazoles (Him) at the axial positions. The adjacent cations are bridged by CF3SO3 ion through NH center dot center dot center dot O hydrogen bonds between Him and CF3SO3 to give a one-dimensional chain structure {[Fe-III(Him)(2)(4MeO-hapen)]CF3SO3}(1 infinity). The magnetic susceptibility measurements showed that complex exhibits an abrupt spin transition between a single HS phase and a symmetry-breaking [HS-HS-HS-LS] phase and another transition around 80 K. The single-crystal X-ray analyses at 296 and 150 K revealed the structures at a single HS and [HS-HS-HS-LS] states. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2015.09.031

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

Solvent-free spin crossover (SCO) iron(III) complex, [Fe-III(Him)(2)(hapen)] SbF6 (Him = imidazole, H(2)hapen = N,N'-bis(2-hydroxyacetophenylidene) ethylenediamine), is synthesized. The Fe-III ion has an octahedral coordination geometry, with N2O2 donor atoms of hapen and N-2 atoms of two imidazoles at the axial positions. The saturated five-membered chelate ring of hapen moiety assumes a gauche-type delta- or lambda-conformation to give chiral species of d-[Fe-III(Him)(2)(hapen)](+) or lambda-[Fe-III(Him)(2)(hapen)](+). One imidazole is hydrogen-bonded to phenoxo oxygen atom of hapen of the adjacent unit to give a hydrogen-bonded chiral one-dimensional structure, {delta-[Fe-III(Him) (2)(hapen)](+)}1 infinity or {lambda-[Fe-III(Him)(2)(hapen)](+)}1 infinity. The adjacent chains with the opposite chiralities are arrayed alternately. The temperature dependences of the magnetic susceptibilities revealed an abrupt one-step spin transition between high-spin (S = 5/ 2) and low-spin (S = 1/2) states at the spin transition temperature of T-1/2 = 105 K. The crystal structures were determined at 296 and 100 K, where the populations of HS:LS of high-and low-spin ratio are evaluated to be 1:0 and 0.3:0.7, respectively, based on magnetic measurements. During the spin transition from 296 K to100 K, the average Fe-N distance and O-Fe-O angle decrease to a regular octahedron by 0.16 angstrom and 13.4 degrees, respectively. The structural change in the coordination environment is transmitted to the adjacent spin crossover (SCO) sites along the chiral 1D chain through hydrogen-bonds. The abrupt SCO profile and the spin transition temperature for the isomorphous compounds [Fe-III(Him)(2)(hapen)]Y (Y = PF6, AsF6, SbF6) are ascribed to the chiral hydrogen-bonded 1D structure and chain-anion interaction.

DOI： 10.3390/magnetochemistry1010072

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

Solvent-free spin crossover Fe-II complex fac-[Fe-II(HLn-Pr)(3)]Cl center dot PF6 was prepared, where HLn-Pr denotes 2-methylimidazol-4-yl-methylideneamino-n-propyl. The magnetic susceptibility measurements at scan rate of 0.5 K min(-1) showed two successive spin transition processes consisting of the first spin transition T-1 centered at 122 K (T-1 up arrow = 127.1 K, T-1 down arrow = 115.8 K) and the second spin transition T-2 centered at ca. 105 K (T-2 up arrow = 115.8 K, T-2 down arrow = 97.2 K). The magnetic susceptibility measurements at the scan rate of 2.0, 1.0, 0.5, 0.25, and 0.1 K min(-1) showed two scan speed dependent spin transitions, while the Mossbauer spectra detected only the first spin transition T-1. The crystal structures were determined at 160, 143, 120, 110, 95 K in the cooling mode, and 110, 120, and 130 K in the warming mode so as to follow the spin transition process of high-spin HS -> HS(T-1) -> HS(T-2) -> low-spin LS -> LS(T-2) -> LS(T-1) -> HS. The crystal structures at all temperatures have a triclinic space group P (1) over bar with Z = 2. The complex-cation has an octahedral N-6 coordination geometry with three bidentate ligands and assume a facial-isomer with Delta- and Lambda-enantimorphs. Three imidazole groups of fac-[Fe-II(HLn-Pr)(3)](2+) are hydrogen-bonded to three Cl- ions. The 3:3 NH(imidazole)center dot center dot center dot Cl- hydrogen-bonds form a stepwise ladder assembly structure, which is maintained during the spin transition process. The spin transition process is related to the structural changes of the FeN6 coordination environment, the order-disorder of PF6- anion, and the conformation change of n-propyl groups. The Fe-N bond distance in the HS state is longer by 0.2 angstrom than that in the LS state. Disorder of PF6- anion is not observed in the LS state but in the HS state. The conformational changes of n-propyl groups are found in the spin transition processes except for HS --> HS(T-1) -> HS(T-2).

DOI： 10.1021/acs.inorgchem.5b00701

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Three iron(III) complexes, [Fe-III(Him)(2)(n-MeOhapen)]PF6 (1: n = 4, 2: n = 5, 3: n = 6), where Him = imidazole and n-MeOhapen = N,N'-bis(n-methoxy-2-oxyacetophenylidene)ethylenediamine, were synthesized. Each Fe-III ion was coordinated by N4O2 donor atoms of equatorial n-MeOhapen and two axial Him. The saturated FeC2N2 chelate ring involving the ethylenediamine moiety adopted a gauche conformation and the two phenylidene planes of [Fe-III(Him)(2)(n-MeOhapen)](+) were oriented opposite to the FeO2N2 coordination plane. Two adjacent [Fe-III(Him)(2)(4-MeOhapen)](+) cations in 1 were connected via PF6 ions by hydrogen bonds between the imidazole group and PF6 to give a one-dimensional chain. Two adjacent cations in 2 were connected via hydrogen bonds between the phenylidene oxygen and imidazole atoms to form a cyclic dimer structure. Two EtOH molecules were involved in a hydrogen-bonded cyclic dimer structure in 3. Compounds 1 and 2 showed spin crossover behavior, but 3 showed incomplete spin crossover. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2015.03.034

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Two iron(III) complexes [(FeX2L)-X-III]BPh4 center dot solvents (X = 1-Meim (1), Him (2)) were synthesized and the crystal structures were determined, where H2L = N, N'-bis(3-ethoxycarbonylsalicylidene) ethylenediamine, 1-Meim = 1-methylimidazole, Him = imidazole, BPh4 = tetraphenylborate. Fe-III ion has an octahedral coordination environment by N2O2 donor atoms of equatorial L-2 and N-2 donor atoms of axial imidazoles. Complex 1 is described as isolated molecule, while complex 2 has a hydrogen-bonded cyclic dimer structure constructed by hydrogen-bond between imidazole group and ethoxycarbonyl oxygen via ethanol. Complex 1 is in a high-spin (S = 5/2) state over the whole temperature region 5-300 K, while complex 2 showed a gradual complete spin equilibrium between high and low-spin states at T-1/2 = 192 K. (C) 2015 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.ica.2015.03.008

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Spin crossover (SCO) iron(III) complexes exhibiting thermal hysteresis, [Fe-III(Him)(2)(3-MeOsalen)]center dot H2O center dot EtOH center dot X (Him = imidazole, 3-MeOsalen = N, N'-bis(3-methoxysalicylidene) ethylenediaminato, and X = PF6, AsF6, SbF6), were synthesized in ethanol. The FeIII ion has an octahedral coordination geometry with N2O2 donor atoms of the planar tetradentate ligand (3-MeOsalen) and two nitrogen atoms of two imidazoles at the axial positions. Through H2O and EtOH the complex-cations are assembled into a hydrogen-bonded 2D network structure and the anion X is accommodated in the void of the 2D network. The temperature dependences of the magnetic susceptibilities revealed an abrupt and two-step spin transition with thermal hysteresis for the PF6 and AsF6 salts. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2015.01.047

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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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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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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：AMER CHEMICAL SOC  

Terbium(III) and dysprosium(III) complexes with a tripodal N-7 ligand containing three imidazoles (H3L) and a bidentate acetate ion (OAc-), [Ln(III)(H3L)(OAc)](ClO4)(2)center dot MeOH center dot H2O (Ln = Tb, 1; Ln = Dy, 2), were synthesized and studied, where H3L = tris[2-(((imidazol-4-yl)methylidene)amino)ethyl]amine. The Tb-III and Dy-III complexes have an isomorphous structure, and each Tb-III or Dy-III ion is coordinated by the tripodal N-7 and the bidentate acetate ligands, resulting in a nonacoordinated capped-square-antiprismatic geometry. The magnetic data, including temperature dependence of the magnetic susceptibilities and field dependence of the magnetization, were analyzed by a spin Hamiltonian, including the crystal field effect on the Tb-III ion (4f(8), J = 6, S = 3, L = 3, g(J) = 3/2, F-7(6)) and the Dy-III ion (4f(9),J = 15/2, S = 5/2, L = 5, g(J) = 4/3, H-6(15/2)). The Stark splittings of the ground states F-7(6) of the Tb-III ion and H-6(15/2) of the Dy-III ion were evaluated from the magnetic analyses, and the energy diagram patterns indicated an easy axis (Ising type) anisotropy for both complexes, which is more pronounced for 2. The solid-state emission spectra of both complexes displayed sharp bands corresponding to the f-f transitions, and the fine structures assignable to the D-5(4) -> F-7(6) transition for 1 and the F-6(9/2) -> H-6(15/2) transition for 2 were related to the energy diagram patterns from the magnetic analyses. 1 and 2 showed an out-of-phase signal with frequency dependence in alternating current (ac) susceptibility under a dc bias field of 1000 Oe, indicative of a field-induced SIM.

DOI： 10.1021/ic501453h

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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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Two Tb-III complexes with the same N6O3 donor atoms but different coordination geometries, "fac"- [Tb-III(HLDL-ala)(3)]center dot 7H(2)O (1) and "mer"- [Tb-III(HLDL-phe)(3 center dot)7H(2)O (2), were synthesized, where H2LDL-ala and H2L2DL-phe are N-imidazol-4-yl)methylidene-DL-alanine and -DL-phenylalanine, respectively. Each Tb-III ion is coordinated by three electronically mononegative NNO tridentate ligands to form a coordination geometry of a tricapped trigonal prism. Compound 1 consists of enantiomers "fac"-[Tb-III(HLD-ala)(3)] and "fac"-[Tb-III(HLL-ala)(3)], while 2 consists of "mer"-[Tb-III(HLD-phe)(2)(HLD-Phe)(HLL-Phe)(2)]. Magnetic data were analyzed by a spin Hamiltonian including the crystal field effect on the Tb-III ion (4f(8), J = 6, S = 3, L = 3, gi = 3/2, F-7(6)). The Stark splitting of the ground state 7F6 was evaluated from magnetic analysis, and the energy diagram pattern indicated easyplane and easy-axis (Ising type) magnetic anisotropies for 1 and 2, respectively. Highly efficient luminescences with phi = 0.50 and 0.61 for 1 and 2, respectively, were observed, and the luminescence fine structure due to the D-5(4) -> F-7(6) transition is in good accordance with the energy diagram determined from magnetic analysis. The energy diagram of 1 shows an approximate single-well potential curve, whereas that of 2 shows a double- or quadruple-well potential within the F-7(6) multiplets. Complex 2 displayed an onset of the out-of-phase signal in alternating current (ac) susceptibility at a direct current bias field of 1000 Oe on cooling down to 1.9 K. A slight frequency dependence was recorded around 2 K. On the other hand, 1 did not show any meaningful out-of-phase ac susceptibility. Pulsed-field magnetizations of 1 and 2 were measured below 1.6 K, and only 2 exhibited magnetic hysteresis. This finding agrees well with the energy diagram pattern from crystal field calculation on 1 and 2. DFT calculation allowed us to estimate the negative charge distribution around the Tb-III ion, giving a rationale to the different magnetic anisotropies of 1 and 2.

DOI： 10.1021/ic5001599

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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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A novel mononuclear iron(II) complex of a 1,2,3-triazole-containing ligand, [(FeLPh)-L-II](NTf2)(2) [L-Ph: tris(2-{[(1-phenyl-1,2,3-triazol-4-yl)methylidene]amino}ethyl)amine and NTf2: bis(trifluoromethanesulfonyl)imide], was synthesized. The complex shows a gradual one-step spin crossover at around room temperature with T-1/2 = 280 K. The complex cations, [(FeLPh)-L-II](2+), are linked via CH/pi and pi-pi interactions forming a two-dimensional layer. The cationic layers are linked together by NTf2- ions via CH center dot center dot center dot X (X = N, O, and F) hydrogen-bonding interactions to form an extended three-dimensional structure.

DOI： 10.1246/cl.140133

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The solvent-free spin crossover iron(III) complex [Fe-III(Him)(2)(hapen)]AsF6 (Him = imidazole, H(2)hapen = bis(2-hydroxyacetophenylidene)ethylenediamine), exhibiting thermal hysteresis, was synthesized and characterized. The Fern ion has an octahedral coordination geometry, with N2O2 donor atoms of the planar tetradentate ligand (hapen) and two nitrogen atoms of two imidazoles at the axial positions. One of two imidazoles is hydrogen-bonded to the phenoxo oxygen atom of hapen of the adjacent unit to give a hydrogen-bonded one-dimensional chain, while the other imidazole group is free from hydrogen bonding. The temperature dependencies of the magnetic susceptibilities and Mossbauer spectra revealed an abrupt spin transition between the high-spin (S = 5/2) and low-spin (S = 1/2) states, with thermal hysteresis.

DOI： 10.1021/ic402947u

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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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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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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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Carbonato-bridged Zn(2)(II)Ln(2)(III) complexes [(mu(4)-CO3)(2){Zn(II)L(n)Ln(III)(NO3)}(2)]center dot solvent were synthesized through atmospheric CO2 fixation reaction of [(ZnLn)-L-II(H2O)(2)]center dot xH(2)O, Ln(III)(NO3)(3)center dot 6H(2)O, and triethylamine, where Ln(III) = Gd-III, Tb-III, Dy-III; L-1 = N,N'-bis(3-methorry-2-oxybenzylidene)-1,3-propanediaminato, L-2 = N,N'-bis(3-ethorry-2-oxybenzylidene)1,3-propanediaminato. Each Zn(2)(II)Ln(2)(III) structure possessing an inversion center can be described as two di-mu-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO32- ions. The Zn-II ion has square pyramidal coordination geometry with N2O2 donor atoms of L-n and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L-n, two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(2)(II)Ln(2)(III) complexes are analyzed on the basis of the dicarbonato-bridged binuclear structure, as the Zn-II ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L-1) and ZnGd2 (L-2) show a ferromagnetic Gd-III-Gd-III interaction with J(Gd-Gd)Zn(2)(II)Ln(2)(III) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)(S) over cap (Gd1).(S) over cap (Gd2). The magnetic data of the complexes (Ln(III) = D 11) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of (Zn2Tb2III)-Tb-II complexes were observed, while those of (Zn2Dy2III)-Dy-II were not detected. The fine structure assignable to the D-5(4) -> F-7(6) transition of ZnTb1 and ZnTb2 is in good accord with the energy pattern from the magnetic analysis. The Zn(2)(II)Ln(2)(III) complexes (Ln(III) = Tb-III, Dy-III) showed an out-of-phase signal with frequency-dependence in alternating current susceptibility, indicative of single molecule magnet. Under a dc bias field of 1000 Oe, the signals become significantly more intense and the energy barrier, Delta/k(B), for the magnetic relaxation was estimated from the Arrhenius plot to be 39(1) and 42(8) K for ZnTb1 and ZnTb2, and 52(2) and 67(2) K for ZnDyl and ZnDy2, respectively.

DOI： 10.1021/ic4022273

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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/ic401667v

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Atmospheric CO2 fixation of [Ni-II(3-MeOsaltn)(H2O)(2)]center dot 2.5H(2)O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene) -1,3-propanediaminato], Ln(III)(NO3)(3)center dot 6H(2)O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni-2(II),Ln(2)(III) complexes [(mu(4)-CO3)(2){Ni-II(3-MeOsaltn)(MeOH)-Ln(III)(NO3)}(2)] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(mu(4)-CO3)(2){Ni-II(3-MeOsaltn)(H2O)-Ln(III)(NO3)}(2)]center dot 2CH(3)CN center dot 2H(2)O (2Gd, 2Tb, and 2Dy). For both series, each Ni(2)(II)Ln(2)(III) structure can be described as two di-mu-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO32- units to form a carbonato-bridged (mu(4)-CO3)(2){Ni(2)(II)Ln(2)(III)) structure. The high-spin Ni-II ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O-9 donor atoms from Ni-II(3-MeOsaltn), bidentate NO3-, and one and two oxygen atoms of two CO32- ions. The NO3- ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni-II and Ln(III) ions (Ln(III) = Gd-III, Tb-III, Dy-III) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb-III or Dy-III ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the (Ni2Gd2III)-Gd-II complexes but exhibited an out-of-phase signal for (Ni2Tb2III)-Tb-II and (Ni2Dy2III)-Dy-II, indicative of slow relaxation of magnetization. The energy barriers, Delta/k(B), for the spin flipping were estimated from the Arrhenius plot to be 12.2(7) and 6.1(3) K for 1Tb and 2Tb, respectively, and 18.1(6) and 14.5(4) K for 1Dy and 2Dy, respectively, under a dc bias field of 1000 Oe. Compound 1Dy showed relatively slow relaxation of magnetization reorientation even at zero dc applied field with Delta/k(B) = 6.6(4) K.

DOI： 10.1021/ic4008312

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

A series of 3d-4f binuclear complexes, [M(3-MeOsaltn)(MeOH)(x)(ac)Ln(hfac)(2)] (x = 0 for M = Cu-II, Zn-II; x = 1 for M = Co-II, Ni-II; Ln Gd-III, Dy-III, La-III), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propane-diaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M-II-Ln(III) binuclear structure. The Cu-II-Ln(III) and Zn-II-Ln(III) complexes are crystallized in an isomorphous triclinic space group PT, where the Cu-II or Zn-II ion has square pyramidal coordination geometry with N2O2 donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co-II-Ln(III) and Ni-II-Ln(III) complexes are crystallized in an isomorphous monoclinic space group P2(1)/c, where the Co-II or Ni-II ion at the high-spin state has an octahedral coordination environment with N2O2 donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln(III) ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of "ligand-complex" M(3-MeOsaltn), four oxygen atoms of two hfac(-), and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Li-III (Tb-III, Dy-III) and to a lesser extent the M-II (N-III, Co-II) components, the magnetic interaction between M-II and Ln(III) ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M-II-Ln(III), Zn-II-Ln(III), and complexes. The differences of chi T-M and M(H) values for the M-II-Ln(III), Zn-II-Ln(III) and those for the M-II-La-III complexes, that is, Delta(T) = (chi T-M)(MLn) - (chi T-M)(znLn)-(chi T-M)(MLa) = J(MLn)(T) and Delta(H) = M-MLn(H) - M-ZnLn(H) - M-MLa(H) = J(MLn)(H), give the information of 3d-4f magnetic interaction. The magnetic interactions are ferromagnetic if M-II = (Cu-II, Ni-II, and Co-II) and Ln = (Gd-III, Tb-III, and Dy-III) The magnitudes of the ferromagnetic interaction, J(MLn)(T) and J(Mln)(H), are in the order Cu-II-Gd-III > Cu-II-Dy-III > Cu-II-Tb-III, while those are in the order of M-II-Gd-III approximate to M-II-Tb-III > M-II-Dy-III for M-II = Ni-II and Co".Alternating current (ac) susceptibility measurements demonstrated that the Ni-II-Dy-III and Co-II-Tb-III complexes showed out-of-phase signal with frequency-dependence and the Ni-II-Dy-III and Co-II-Dy-II complexes showed small frequency-dependence. The energy barrier for the spin flipping was estimated from the Arrhenius plot to be 14.9(6) and 17.0(4) K for the (NiII-TbIII) and Co-II-Tb-III complexes, respectively, under a dc bias field of 1000 Oe.

DOI： 10.1021/ic400594u

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Five iron(III) complexes of [Fe-III(Him)(2)(hapen)]Y center dot solvent with five different counter anions were synthesized, where Him = imidazole, H(2)hapen = N,N'-bis(2-hydroxyacetophenylidene)ethylenediamine, Y = BPh4- (1), CF3SO3- (2), PF6- (3), ClO4- (4), and BF4- (5), and solvent = methanol or H2O. Each Fe-III ion has octahedral coordination geometry with N2O2 donor atoms of the equatorial tetradentate ligand (hapen) and two nitrogen atoms of two imidazoles at the axial positions. The imidazole group is hydrogen-bonded to the phenoxo oxygen atom of hapen of the adjacent unit and/or to the counter anion or solvent molecule, to give three types of assembly structures involving linear dimer, cyclic dimer, and one-dimensional zigzag chain. Compound 1, with a cyclic dimer, and 2 and 3, with a one-dimensional chain, showed spin-equilibrium behavior between high-spin (S = 5/2) and low-spin (S = 1/2) states, whereas 4 and 5, with linear dimers, are high-spin complexes. Compound 3 shows abrupt spin transition with small thermal hysteresis. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2013.01.021

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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 H-1 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 {L2(2) = 2-amino-1-(2-oxybenzamido) propane; L3(2) = trans-1-amino-2-(2-oxybenzamido)cyclohexane}, [Co(L3)(2)] showed diastereoselectivity while [Co(L2)(2)] did not. Furthermore, PPh4[Co(L1)(2)] (L1(2) = 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. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2013.01.011

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A bidentate 2-methylimidazol-4-yl-methylideneaminobenzyl ligand (HLMe-Renz) reacts with (FeCl2)-Cl-II center dot 4H(2)O and NaPF6 at a 3:1:1 molar ratio to yield a tris(2-methylimidazol-4-yl-methylideneaminobenzyl)iron(II) chloride hexafluorophosphate solvate with the formula of [Fe-II (HLMe-Benz)(3)]C1 center dot PF6 center dot solvent. Meridional and facial geometrical isomers, i.e., mer-[Fe-II (HLMe-Benz)(3)]C1 center dot PF6 center dot 1.5H(2)O (1 center dot PF6.1.5H(2)O) and fac[Fell( [Fe-II (HLMe-Benz)(3)]C1 center dot PF6 center dot EtOH.H2O (2-PF6 center dot EtOH center dot H2O), were selectively crystallized from methanol and ethanol solutions, respectively. fac-[Fe-II (HLMe-Benz)(3)]C1 center dot PF6 center dot H2O (2.SbF6 center dot 1.H2O) and fac-[Fe-II (HLMe-Benz)(3)]C1 center dot EtOH center dot H2O(2.ClO4 center dot EtOH2O) are synthesized in ethanol, using the corresponding anions. Each Fell ion has an octahedral coordination geometry with N6 donor atoms from three bidentate ligands. All three imidazole groups in both thefac- and mer-[Fe-II (HLMe-Benz)(3)](2+) cations are hydrogen-bonded to neighboring three Cl- ions, and each Cl- ion is hydrogen-bonded to three imidazole groups of three neighboring complex cations; this results in the formation of hydrogen-bonded assembly structures. mer-Complex 1.PF6.1.5H(2)O forms a heterochiral two-dimensional (2D) network structure comprised of cyclic [Fe-II (HLMe-Benz)(3)](2+) ... Cl-}(4) units with an Delta Delta Delta or Lambda Lambda Delta configuration; the PF6- ions occupy the spaces between the 2D layers. All the fac-complexes have isomorphous cubane-like tetrameric structures, i.e.,.Cl},. C114. The tetranuclear structure comprises four homo-chiral {fac-[Fe-II (HLMe-Benz)(3)](2+) ... Cl-3(-)} cations and four Cl- ions interconnected by twelve imidazole-chloride hydrogen bonds to form a chiral cubane supramolecule that encapsulates one counter anion. In the crystal lattice, the cubane-like tetramers with opposite chiralities are alternately arrayed. The temperature dependence of the magnetic susceptibilities and Mossbauer spectra reveal that the fac-complexes show incomplete spin crossover behavior, while the mer-complex shows a gradual spin crossover between high-spin (HS, S= 2) and low-spin (LS, S = 0) states. (C) 2013 Published by Elsevier Ltd.

DOI： 10.1016/j.poly.2013.02.003

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

A spin-crossover iron(II) complex, fac-[Fe-II(HLn-Hx)(3)]Cl center dot PF6 (1), that exhibits stepwise spin transition and thermal hysteresis was synthesized by using the ligand 2-methylimidazol-4-ylmethylidene-n-hexylamine (HLn-Hx). Four complex cations (fac-[Fe-II(HLn-Hx)(3)](2+)) and four Cl- anions associate through twelve imidazole center dot center dot center dot Cl- H bonds to give a tetrameric cubane-like assembly, and one PF6- anion is encapsulated within the cavity of the cubane. Magnetic susceptibility measurements showed a three-step spin transition, and the spin-crossover profile became less pronounced as the sweep rate increased. At a sweep rate of 0.5 K min(-1), the midpoint temperatures of the three steps are T-c(up arrow) = 131.2, 144.2, and 154.2 K in the heating mode and T-c(down arrow) = 116.8, 137.8, and 151.8 K in the cooling mode. The respective thermal hystereses were evaluated to be 14.4, 6.3, and 2.4 K wide.

DOI： 10.1002/ejic.201201298

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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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Atmospheric CO2 fixation by a basic reaction mixture of [Ni-II(3-MeOsaltn)(H2O)(2)] and Gd-III(NO3)(3)center dot 6H(2)O gave a carbonate-bridged tetranuclear (Ni2Gd2III)-Gd-II complex, (mu(4)-CO3)(2)[Ni-II(3-MeOsaltn)(MeOH)Gd-III(NO3)](2)center dot H2O, where 3-MeOsaltn denotes N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato. The tetranuclear structure possessing an inversion center can be described as two [(NiGdIII)-Gd-II] binuclear units bridged by two carbonate CO32- ions: two oxygen atoms of the carbonate ion bridge the high-spin Ni-II and Gd-III ions of a binuclear unit and the remaining oxygen atom of the carbonate ion coordinates to a Gd-III ion of the adjacent binuclear unit. The temperature-dependent magnetic susceptibilities, from 1.9 to 300 K, follow the Curie-Weiss equation of chi T-M= C/(T - theta) with theta = +2.3 K and C = 18.24 cm(3) K mol(-1), suggesting a ferromagnetic interaction. The magnetic data were well reproduced assuming two independent [Ni-II-Gd-III] binuclear units with the parameters of J(Ni-Gd) = +1.2 cm(-1) and D = +2.1 cm(-1). (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.inoche.2012.08.022

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Two new iron(II) complexes, [Fe-II(HLMe)(2)](ClO4)(2) (1) and its ethanol adduct [Fe-II(HLMe)(2)](ClO4)(2)center dot EtOH (2) were synthesized by selective crystallization in methanol and ethanol, respectively, where HLMe is a tridentate N-3 ligand, 2-methylimidazol-4-yl-methylideneamino-2-ethylpyridine, and their structures and magnetic properties were investigated. Each compound contains the same octahedrally N-6 coordinated complex-cation [Fe-II(HLMe)(2)](2+) and two ClO4- ions. The non-solvated compound 1 is the HS (S = 2) complex without spin transition over the 5-300 K temperature range, and has the homochiral 1D helical-chain structure constructed of the intermolecular NH center dot center dot center dot O- hydrogen bonds between ClO4- ions and neighboring imidazole NH groups of the [Fe-II(HLMe)(2)](2+) cations. The ethanol adduct 2 shows a gradual one-step spin transition between the HS (S = 2) and LS (S = 0) states, and has two crystallographically independent iron(II) sites with two NH(imidazole)center dot center dot OH(EtoH)center dot center dot center dot O(ClO4-) hydrogen bonds of Fe(1) site and two NH(imidazole)center dot center dot center dot O(ClO4-) hydrogen bonds of Fe(2) site. There are no further intermolecular interactions to produce an extended structure in a crystal lattice of 2. The presence or absence of thermal spin transition is related to the structural distortion of each HS molecule of these perchlorate salts associated with their surroundings of intermolecular hydrogen bonds. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2012.09.010

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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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A bidentate 2-methylimidazol-4-yl-methylideneaminobenzyl ligand (HLMe-Benz) reacts with (FeCl2)-Cl-II center dot 4H(2)O and NaPF6 at a 3:1:1 molar ratio to yield a tris(2-methylimidazol-4-yl-methylideneaminobenzyl)iron(11) chloride hexafluorophosphate solvate with the formula of Well( HLMe-Benz)3]Cl center dot PF6.solvent. Meridional and facial geometrical isomers, i.e., mer-(Fe-II (HLMe-Benz)(3)]Cl center dot PF6.1.5H(2)O (1.PF6.1.5H(2)O) and fac-[Fe-II(HLMe-Benz)(3)]Cl.PF6 center dot EtOH center dot H2O (2-PF6.EtOH center dot H2O), were selectively crystallized from methanol and ethanol solutions, respectively. fac-[Fe-II(HLMe-Be1z)(3)]Cl center dot SbF6 center dot H2O (2.SbF6 center dot H2O) and fac-[Fe-II(HLMe-Benz)(3)]Cl. ClO4 center dot EtOH center dot H2O (2.ClO4 center dot EtOH center dot H2O) are synthesized in ethanol, using the corresponding anions. Each Fell ion has an octahedral coordination geometry with N-6 donor atoms from three bidentate ligands. All three imidazole groups in both the fac- and mer-[Fe-II(HLMe-Benz)(3)](2+) cations are hydrogen-bonded to neighboring three Cl- ions, and each Cl- ion is hydrogen-bonded to three imidazole groups of three neighboring complex cations; this results in the formation of hydrogen-bonded assembly structures. met-Complex 1.PF6-15H(2)O forms a heterochiral two-dimensional (2D) network structure comprised of cyclic (mer[Fe-II(HLMe-Benz)(3)](2+)center dot center dot center dot Cl-)3 units with an Delta Delta Lambda or Lambda Lambda Delta configuration; the PF6- ions occupy the spaces between the 20 layers. All the fac-complexes have isomorphous cubane-like tetrameric structures, i.e., {fac-[Fe-II(HLMe-Benz)(3)](2+)center dot center dot center dot Cl-)(4). The tetranuclear structure comprises four homo-chiral fac-Delta- or fac-Lambda-[Fell(HLMe-Benz)(3)](2+) I cations and four Cl- ions interconnected by twelve imidazole-chloride hydrogen bonds to form a chiral cubane supramolecule that encapsulates one counter anion. In the crystal lattice, the cubane-like tetramers with opposite chiralities are alternately arrayed. The temperature dependence of the magnetic susceptibilities and Mossbauer spectra reveal that the fac-complexes show incomplete spin crossover behavior, while the mer-complex shows a gradual spin crossover between high-spin (HS, S = 2) and low-spin (LS, S = 0) states. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2012.06.085

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Two copper(II) complexes with the protonated ligands [(CuCIHLDL)-C-II] and [(CuCIHLL)-C-II] were prepared, where HLDL, denotes N-[(5-methylimidazol-4-yl)methylidenel-DL-phenylalanine and HLL denotes its L-form ligand. The deprotonation of [(CuCIHLDL)-C-II] at the imidazole moiety gave an imidazolato-bridged cyclic tetranuclear arrayed [(CuLo)-L-II(H2O)] and [(CuLL)-L-II(H2O)] species, while the deprotonation of [(CuCIHLL)-C-II] gave an octanuclear structure [(Cu8L8L)-L-II center dot 4H(2)O] in which two cyclic tetranuclear species are linked by an intertetramer Cu-O (carboxylate) coordination bond. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2011.11.024

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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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fA series of spin-crossover (SCO) iron(II) compounds, fac-[Fe-II(HLR)(3)]Cl center dot PF6 [R = methyl (Me, 1), ethyl (Et, 2), n-propyl (n-Pr, 3), n-butyl (n-Bu, 4), and n-pentyl (n-Pen, 5)] were synthesized, where HLR denotes a series of [(2-methylimidazol-4-yl)methylidene]-monoallcylamines. The cations fac-[Fe-II(HLR)(3)](2+) and chloride anions associate through 3:3 imidazole center dot center dot center dot chloride hydrogen bonding. This hydrogen-bonding motif gives rise to a variety of assembly structures consisting of a one-dimensional ladder for 3 and 4, two kinds of two-dimensional networks for 1 and 2, and a cubane-like structure for S. The compounds exhibit various types of SCO transitions between high-spin (S = 2) and low-spin (S = 0) states as a result of their intermolecular interactions.

DOI： 10.1021/ic201993z

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A chiral spin crossover iron(II) complex, fac-Lambda-[Fe-II(HLR)(3)](ClO4)(2)center dot EtOH was synthesized and its crystal structures in both the high-spin (HS) and low-spin (LS) states were determined, where HLR denotes 2-methylimidazol-4-yl-methylideneamino-R-(+)-1-methylphenyl. The complex assumes octahedral coordination geometry of N-6 donor atoms by three bidentate ligands HLR. The complex exists as the facial-Lambda-isomer of fac-Lambda-[Fe-II(HLR)(3)](2+) of the possible geometrical fac- and mer-isomers and the Delta- and Lambda-enantiomorphs. The X-ray structural analyses revealed that the R-form of the ligand (HLR) induces the fac-Lambda-isomer of fac-Lambda-[FeII(HLR)(3)](2+) and the S-form of the ligand (HLS) induces the fac-Delta-isomer of fac-Delta-[Fe(HLS)(3)](2+). The complex fac-Delta-[Fe-II(HLR)(3)](ClO4)(2)center dot EtOH shows a complete steep spin crossover between the HS and the LS states at T-1/2 = 195 K. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2011.05.032

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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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A low-spin Fe-III complex, [Fe-III(H2L5-Me)(HL5-Me)](ClO4)(2)center dot EtOH, was prepared by the reaction of Fe-II(ClO4)(2)-6H(2)O and H2L5-Me in ethanol with 1:2 molar ratio and in air, where H2L5-Me: N-[(5-methylimidazol-4-yl)methylidene]histamine. Each complex molecule of [Fe(H2L5-Me)(HL5-Me)](2+) has both fully protonated ligand and mono-deprotonated ligand and acts as a chiral self-complementary building block to produce the homochiral imidazole-imidazolate-bridged zigzag-chain structure. The X-ray analysis confirmed that the adjacent chains with the same chirality are stacked in a crystal lattice to give a chiral crystal (conglomerate). Low-spin Fe-III was revealed by the magnetic susceptibility and Mossbauer measurements.

DOI： 10.1246/bcsj.20100299

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A iron(II) complex of the linear hexadentate N-6 ligand H2L2-3-2, [Fe(H2L2-3-2)](ClO4)(2), was synthesized and the spin crossover properties were investigated, where H2L2-3-2 denotes bis[N-(2-methylimidazol-4-yl)methylidene-2-aminoethyl]propanediamine. The complex showed a gradual and reversible one-step spin crossover (SCO) between the high-spin (S = 2) and low-spin (S = 0) states at T-1/2 = 208 K without hysteresis. The crystal structures were determined at 296 and 250 K (HS state), 230, 210, and 200 K (intermediate between the HS and LS states) and 150 and 110 K (LS state). The spin transition from 296 to 150 K accompanies with the conformation change of the chelate rings at the triamine moiety and the formation of the hydrogen bond network in the same space group of orthorhombic Pbcn (no. 60). However, in the LS state at 110 K, the space group changed from orthorhombic Pbcn at 150 K (Pcan when the same axial setting to 110 K was used) to monoclinic P2(1)/a (no. 14) at 110 K, although no spin transition and no change of assembly structure between 150 and 110 K were observed. It give us an idea that the space group transformation is mainly related to the conformational thermodynamic stability of the chelate rings at the triamine moiety and is not directly correlated with the spin transition. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2010.12.016

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Facial- and meridional-isomers of tris[benzyl(2-methylimidazol-4-ylmethylidene)amine]iron(II) chloride hexafluorophosphate with the formulas of fac-[Fe(HLMe-Benz)(3)]Cl center dot PF6 center dot EtOH center dot H2O (1) and mer-[Fe(HLMe-Benz)(3)]Cl center dot PF6 center dot 1.5H(2)O (2) were selectively crystallized in ethanol and methanol, respectively. All three imidazole groups in both the fac- and mer-[Fe(HLMe-Benz)(3)](2+) cations are hydrogen-bonded to neighboring Cl- ions and give the assembly structures. The compounds differ, however, in that 1 has a discrete cubane-like tetranuclear cluster, while 2 forms a two-dimensional (2D) network structure. The magnetic susceptibilities data revealed that 1 and 2 are spin crossover complexes.

DOI： 10.1246/cl.2011.72

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Two FeII complexes fac-[Fe-II(HLn-Pr)(3)]Cl center dot Y (Y = AsF6 (1) and BF4 (2)) were synthesized, where HLn-Pr is 2-methylimidazole-4-yl-methylideneamino-n-propyl. Each complex-cation has the same octahedral N-6 geometry coordinated by three bidentate ligands and assumes facial-isomerism, fac-[Fe-II(HLn-Pr)(3)](2+) with Delta- and K-enantiomorphs. Three imidazole groups per Delta- or K-fac-[Fe-II(HLn-Pr)(3)](2+) are hydrogen-bonded to three Cl- ions or, from the viewpoint of the Cl- ion, one Cl- ion is hydrogen-bonded to three neighbouring fac-[Fe-II(HLn-Pr)(3)](2+) cations. The 3 : 3 NH center dot center dot center dot Cl- hydrogen bonds between Delta- or K-fac-[Fe-II(HLn-Pr)(3)](2+) and Cl- generate two kinds of assembly structures. The directions of the 3 : 3 NH center dot center dot center dot Cl- hydrogen bonds and hence the resulting assembly structures are determined by the size of the anion Y, though Y is not involved into the network structure and just accommodated in the cavity. Compound 1 has a 1D ladder structure giving a larger cavity, in which the Delta- and K-fac-[Fe-II(HLn-Pr)(3)](2+) enantiomorphs are bridged by two NH center dot center dot center dot Cl- hydrogen bonds. Compound 2 has a 2D network structure with a net unit of a cyclic trimer of {fac-[Fe-II(HLn-Pr)(3)](2+) center dot center dot center dot Cl- } 3 giving a smaller cavity, in which Delta- or K-fac-[Fe-II(HLn-Pr)(3)](2+) species with the same chirality are linked by NH center dot center dot center dot Cl- hydrogen bonds to give a homochiral 2D network structure. Magnetic susceptibility and Mossbauer spectral measurements demonstrated that compound 1 showed an abrupt one-step spin crossover with 4.0 K thermal hysteresis of T-c down arrow = 125.5 K and T-c up arrow = 129.5 K and compound 2 showed no spin transition and stayed in the high-spin state over the 5-300 K temperature range.

DOI： 10.1039/c1dt11063b

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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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Trinuclear linear 3d-4f-3d complexes (3d = Mn-II, Fe-II, Co-II, Zn-II and 4f = La-III, Gd-III, Tb-III, Dy-III) were prepared by using a tripodal nonadentate Schiff base ligand, N,N',N ''-tris(2-hydroxy-3-methoxybenzilidene)-2-(aminomethyl)-2-methyl-1,3-propanediamine. The structural determinations showed that in these complexes two distorted trigonal prismatic transition metal complexes of identical chirality are assembled through 41 cations. The Mn and Fe entities crystallize in the chiral space group P2(1)2(1)2(1) as pure enantiomers; the cobalt complexes exhibit a less straightforward behavior. All Mn, Fe, and Co complexes experience M-II-Ln(III) ferromagnetic interactions. The Mn-Gd interaction is weak (0.08 cm(-1)) in comparison to the Fe-Gd (0.69 cm(-1)) and Co-Gd (0.52 cm(-1)) ones while the single ion zero field splitting (ZFS) term D is larger for the Fe complexes (5.7 cm(-1)) than for the cobalt ones. The cobalt complexes behave as single-molecules magnets (SMMs) with large magnetization hysteresis loops, as a consequence of the particularly slow magnetic relaxation characterizing these trinuclear molecules. Such large hysteresis loops, which are observed for the first time in Co-Ln complexes, confirm that quantum tunnelling of the magnetization does not operate in the Co-Gd-Co complex.

DOI： 10.1021/ic100460w

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Mononuclear [Fe(H2LR)(2)]X-2 (R = H, 2-Me, 5-Me, 2-Et-5-Me; X = ClO4, BF4) and dinuclear [Fe-2(H2LR)(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, H2LR acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H2LR acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate structure. At room temperature, [Fe-2(H2LH)(3)](ClO4)(4) and [Fe-2(H2L2-me)(3)](ClO4)(4) were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H2L2-Me with electron-donating methyl groups being stronger than H2LH, with the order of the ligand field strengths being H2L2-me > H2LH. However, in the mononuclear [Fe(H2LH)(2)](ClO4)(2) and [Fe(H2L2-Me)(2)](ClO4)(2) complexes, a different order of ligand field strengths, H2LH > H2L2-Me, was observed because [Fe(H2O)(2)](ClO4)(2) was in the LS state while Fe(H2L2-me)(2)](ClO4)(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 H2L2-Me ligand and the other ligand in Fe(H2L2-Me)(2)](ClO4)(2) is responsible for the observed change in the spin state. The same is true for [Fe(H2L2-Et-5-Me)2](ClO4)(2), while [Fe(H2L5-Me)2](ClO4)(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(H2LH)(3)](BF4)(4) and [Fe-2(H2L2-Et-5-Me)(3)](ClO4)(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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2-Methylimidazol-4-yl-methylideneamino-2-ethylpyddine (abbreviated as HLMe) is the 1:1 condensation product of 2-methyl-4-formylimidazole and 2-aminoethylpyridine and functions as a bidentate ligand to the iron(II) ion to produce the 3:1 complexes together with anions, [Fe(HLMe)(3)]X-2 (X = PF6 (1), ClO4 (2), BF4 (3)). The magnetic susceptibilities, differential scanning calorimetric measurements, and Mossbauer spectral measurements demonstrated that complexes 1, 2, and 3 showed a steep one-step spin crossover (SCO) between the high-spin (HS, S=2) and low-spin (LS, S = 0) states with small thermal hysteresis. Three complexes have an isomorphous structure and are crystallized in the same monoclinic space group, C2/c, both in the HS and LS states. The iron(II) ion has the octahedral coordination geometry of a facial isomer with N-6 donor atoms of three bidentate ligands, in which an imidazole and an imine nitrogen atom per ligand participate in the formation of the coordination bond, but the pyridine nitrogen is free from coordination. The complex cation fac-[Fe(HLMe)(3)](2+) is a chiral species with a Delta or Lambda isomer, and the adjacent Delta and Lambda isomers are linked alternately by an intermolecular imidazole-pyridine NH center dot center dot center dot N hydrogen bond to produce an achiral 1D chain. The two remaining imidazole moieties per complex are hydrogen-bonded to the anions that occupy the space among the chains. The SCO profile becomes steeper with the decrease of the anion size (73.0 angstrom(3) for PF6-, 54.4 angstrom(3) for ClO4-, and 53.4 angstrom(3) for BF4-). The SCO transition temperature T-1/2 of the PF6 (1), ClO4 (2), and BF4 (3) salts estimated from the magnetic susceptibility measurements are (T-down arrow = 151.8 K, T-up arrow = 155.3 K), (T-down arrow = 184.5 K, T-up arrow = 186.0 K), and (T-down arrow = 146.4 K, T-up arrow = 148.2 K), respectively, indicating that the T-1/2 value is not in accord with the anion size.

DOI： 10.1021/ic9017344

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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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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] <-> [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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Mononuclear [Fe(H2LR)(2)](2+) and dinuclear [Fe(H2LR)(3)](4+) (R = H, 2-Me, 5-Me) complexes containing the new imidazole-4-carbaldehyde azine ligand (H2LH) and its derivatives (H2L2-Me and H2L5-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, H2LR acts as an unsymmetrical tridentate ligand with two imidazole nitrogen atoms and one azine nitrogen atom, while in the dinuclear complexes, H2LR acts as a dinucleating ligand employing four nitrogen atoms to form a triple helicate. At room temperature, [Fe-2(H2LH)(3)](CIO4)(4) and [Fe-2(H2L2-Me)(3)](CIO4)(4) were in the high-spin (HS) and low-spin (LS) states, respectively. The results are in accordance with the ligand field strength of H2L2-Me with electron-donating methyl groups being stronger than H2LH, with the order of the ligand field strengths being H2L2-M (e)> H2LH, However, in the mononuclearjFe(H2LH)(2)](CIO4)(2) and [Fe(H2L2-Me)(2)](CIO4)(2) complexes, a different order of Iigand field strengths, H2LH > H2L2-Me, was observed because [Fe(H2LH)(2)] (CIO4)(2) was in the LS state while [Fe(H2L2-Me)(2)](CIO4)(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 H2L2-Me ligand and the other ligand in [Fe(H2L2-Me)(2)](CIO4)(2) is responsible for the observed change in the spin state. Two kinds of crystals, needles and blocks, were isolated for [Fe2(H2LH)(3)](BF4)(4), and both exhibited a sharp spin transition, [LS-HS] <-> [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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Reaction of vanadium(III) chloride with 8-quinolinol (Hqn) gave a mononuclear vanadium(IV) complex, [VOCl2(H2O)(2)] 1) center dot 2H(2)qn center dot 2Cl center dot CH3CN, and three dinuclear vanadium(IV) complexes: [V2O2Cl2 (qn)(2)(H2O)(2)] (2) center dot Hqn, [V2O2Cl2(qn)(2)(C3H7OH)(2)] (3), and [V2O2Cl2(qn)(2)(C4H9OH)(2)] (4). Reaction of vanadium(III) chloride with 5-chloro-8-quinolinol (HClqn) gave four dinuclear vanadium(IV) complexes: [V2O2Cl2(Clqn)(2)(H2O)(2)] (5) center dot 2HClqn, [V2O2Cl2(Clqn)(2)(C3H7OH)(2)] (6), [V2O2Cl2(Clqn)(2)(C6H5CH2OH)(2)] (7), and [V2O2Cl2(Clqn)(2)(C4H9OH)(2)] (8) center dot 2C(4)H(9)OH. Reaction of vanadium(III) chloride with 5-fluoro-8-quinolinol (HFqn) gave two dinuclear vanadium(IV) complexes: [V2O2Cl2(Fqn)(2)(H2O)(2)] (9) center dot HFqn center dot 2H(2)O and V2O2Cl2(Fqn)(2)(C3H7OH)(2)] (10). X-ray structures of 1 center dot 2H(2)qn center dot 2Cl center dot CH3CN, 3, 4, 6, 7, 8 center dot 2 t-BuOH, and 10 have been determined. As to the mononuclear species 1 center dot 2H2qn center dot 2Cl center dot CH3CN, coordination of Hqn to vanadium does not occur, but protonation to Hqn occurs to give H(2)qn(+), which links 1's through hydrogen bonding, while each of the dinuclear species has a terminal and a bridging qn (or Clqn, Fqn) ligand, giving rise to a (V-O)(2) ring. Magnetic measurements of 3, 4, 6, 7, and 10 in solid form show very weak antiferromagnetic behavior, and the effective magnetic moments are close to spin only value (2.44) of d(1)-d(1) system, while ESR of 3 in THF shows dissociation to monomeric species. Change from mononuclear, 1, to dinuclear, 2, species was followed by the change of electronic spectrum. (C) 2009 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.ica.2009.02.025

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Heterodinuclear [((NiL)-L-II)Ln(III)(hfac)(2)(EtOH)] (H3L = 1,1,1-tris[(salicylideneamino)methyl]ethane; Ln = Eu, Gd, Tb, and Dy; hfac = hexafluoroacetylacetonate) complexes (1 . Ln) were prepared by treating [Ni(H1.5L)]Cl-0.5 (1) with (Ln(hfaC)(3)(H2O)(2)] and triethylamine in ethanol (1:11). All 1 . Ln complexes (1 . Eu, 1 . Gd, 1 . Tb, and 1 . Dy) crystallized in the triclinic space group P (1) over bar (No. 2) with Z = 2 with very similar structures. Each complex is a face-sharing dinuclear molecule. The Ni-II ion is coordinated by the L3- ligand in a N3O3 coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln(III) ion as bridging atoms. The Ln(III) ion is eight-coordinate, with four oxygen atoms of two hfac-'s, three phenolate oxygen atoms of L3-, and one ethanol oxygen atom coordinated. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements showed a ferromagnetic interaction between Ni-II and Gd-III in 1 . Gd. The Ni-II-Ln(III) magnetic interactions in 1 . Eu, 1 . Tb, and 1 . Dy were evaluated by comparing their magnetic susceptibilities with those of the isostructural Zn-II-Ln(III) complexes, [(ZnL)Ln(hfac)(2)(EtOH)] (2 . Ln) containing a diamagnetic Zn-II ion. A ferromagnetic interaction was indicated in 1 . Tb and 1 . Dy, while the interaction between Ni-II and Eu-III was negligible in 1 . Eu. The magnetic behaviors of 1 . Dy and 2 . Dy were analyzed theoretically to give insight into the sublevel structures of the Dy-III ion and its coupling with Ni-II. Frequency dependence in the ac susceptibility signals was observed in 1 . Dy.

DOI： 10.1021/ic8000575

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Mononuclear [Cu(HL)] (1) and trinuclear [Cu-3(L)(2)] (3) complexes were synthesized, where H3L (1,1,1-tris[(salicylideneamino)methyl] ethane) is a tripodal ligand obtained by condensation of 1,1,1-tris(aminomethyl)ethane and salicylaldehyde in a 1:3 mole ratio. Another mononuclear complex [Cu(HL')] (2), where one of the three arms was disconnected probably due to thermal hydrolysis, was also obtained. The crystal structures, electronic spectra, and electrochemical and magnetic properties of the complexes were studied. In 1, one of the arms of H3L is not coordinated to the metal atom, and the ligand serves as a tetradentate N2O2 ligand, the complex assuming a slightly distorted square-planar structure. In the trinuclear complex, an imine nitrogen atom and a phenolate oxygen atom of one arm of each terminal unit coordinate to the central Cu-II ion to form a linear trinuclear complex. The coordination geometry about each Cu is square planar. All of the complexes involve pi-pi stacking interactions between the molecules in the crystal structures, which are responsible for weak magnetic interactions. An electrochemical study of 3 in DMSO showed that the central Cu-II is more easily reduced to Cu-I than the terminal Cu ions. The mononuclear complexes, 1 and 2, show a quasi-reversible Cu-II/I couple almost at the same position as that of the terminal Cu ions of 3.

DOI： 10.1246/bcsj.81.716

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Heterotrinuclear [((NiL)-L-II)(2)Ln(III)(NO3)] complexes (where H3L = 1,1,1-tris[(salicylideneamino)methyl] ethane and Ln = Gd (1), Eu (2), Tb (3), and Dy (4)) were prepared by treating [Ni(H1.5L)]Cl-0.5 with Ln(NO3)(3)center dot 6H(2)O in the presence of triethylamine. Complexes 1 center dot 2CH(3)OH, 3 center dot 2CH(3)OH, and 4 center dot C2H5OH center dot 0.5H(2)O crystallized in the triclinic space group, P (1) over bar (No. 2), with Z = 2, while 2 center dot CH3OH center dot 0.5H(2)O crystallized in the tetragonal space group, I4(1)/a (No. 88), with Z = 8. All the complexes had very similar structures. Each complex was a doubly face-sharing trinuclear molecule. The Ni-II ion is coordinated by the L3- ligand in an N3O3 coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln(III) ion as bridging atoms. The Ln(III) ion is eight coordinate with six phenolate oxygen atoms of the two L3- ligands and two oxygen atoms of NO3-. Coordination of the NO3- group entails a bending of the Ni center dot center dot center dot Ln center dot center dot center dot Ni angle (ca. 140 degrees). All the complexes involve pi-pi and CH-pi interactions between the neighboring molecules to form a three-dimensional structure. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements on 1 showed a ferromagnetic interaction between the Ni-II and Gd-III atoms. A ferromagnetic interaction was also suggested for Ni-II-Tb-III (3) and Ni-II-Dy-III (4).

DOI： 10.1246/bcsj.81.598

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DOI： 10.1107/S0108270108004289

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

The complex [Co(H3L)](ClO4)(3)center dot H2O (1), where H3L (tris[2-(4-imidazoylmethylideneamino) ethyl] amine) is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 molar ratio, was synthesized and optically resolved by fractional crystallization of the dia-stereomeric salt with [Sb-2{(R,R)-tart)(2)](2-) [(R,R)-tart = (2R,3R)-tartrate(4-) ion]. From the less soluble part, Lambda-[Co(H2L)][Sb-2- (R, R) -tart)(2)]center dot 4H(2)O (2) was isolated. Starting from 2, two optically active complexes, Lambda-[Co(H3L)]ClO4)(3)center dot 1.5H(2)O (Lambda-1) and Lambda-[Co(L)] (Lambda-3), were obtained. The crystal structures of these complexes are compared with those of the racemic structures. A-I shows an unusually strong circular dichroism (lambda = 488 nm, Delta epsilon = -7.74 M-1 cm(-1)) in the first d-d absorption band region. The effects of deprotonation-reprotonation of the uncoordinated imidazole NH groups of Lambda-[Co(H3L)](3+) on the UV/Vis and CD spectra and on the cyclic voltammograms were studied in methanol. Although the deprotonation-reprotonation reactions are reversible, the redox couple for the completely deprotonated species [CoIII/II(L)](0/-) is not observed. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

DOI： 10.1002/ejic.200700950

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Bis(imidazolylimine) ligands, H2L (H) and H-2(Me), were prepared from hydrazine and 4-formylimidazole or 2-methyl4-formylimidazole (1:2), respectively. Mononuclear iron(II) complexes, [Fe(H2LH)(2)](CIO4)(2)center dot MeOH and [Fe(H2LMe)(2)](CIO4)(2)center dot 2H(2)O, were in the LS and HS states, respectively, in the temperature range 5-300K. A triple-helicate [Fe-2(H2LMe)(3)](CIO4)(4), showed an abrupt [LS-HS] to [HS-HS] spin transition at 240K, while [Fe-2(H2LMe)(3)](CIO4)(4) remained in the LS state in the temperature range 5-300 K.

DOI： 10.1246/cl.2007.1284

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The effect of a counteranion on chiral recognition inducing conglomerate crystallization of a cobalt(III) complex is reported. An achiral tripodal ligand involving three imidazole groups, tris{[2-{(imidazol-4-yl)methylidene}amino]-ethyl}amine (H3L), was prepared by condensation of tris(2-aminoethyl)amine and 4-formylimidazole in a 1:3 mole ratio. The reaction of H3L and trans-[(CoCl2)-Cl-III(PY)(4)](+) afforded the chiral (Delta or Lambda) [Co-III(H3L](3+) complex. The formally hemideprotonated complexes [Co-III(H1.5L)]X-1.5 center dot nH(2)O (where X = Cl, Br, I, BF4, ClO4, or PF6) were synthesized by controlled deprotonation of the uncoordinated imidazole NH groups of [Co(H3L)](3+). In crystals of the hemideprotonated complex, two components, [Co(H3L)]3+ and [Co(L)], with the same absolute configuration are linked by imidazoleimidazolate hydrogen bonds to form an extended homochiral 2D sheet structure, which is composed of a hexanuclear unit with a trigonal void. There are two ways of stacking the sheets: One is via homochiral stacking, and the other is via heterochiral stacking. When the size of the counterion is small (i.e., X = Cl, Br, 1, or BF4), adjacent homochiral sheets with the same chirality are stacked to form a homochiral crystal (conglomerate). With large anions (i.e., ClO4- and PF6-), a homochiral sheet consisting of Delta enantiomers and a sheet consisting of Lambda enantiomers are stacked alternately to give a heterochiral crystal (a racemic crystal). Optically active Lambda-[Co(H1.5L)](ClO4)(1.5)-H2O was synthesized from Lambda-[Co(H3L)](3+), and the crystal structure was compared to that of the racemic complex. There are two conflicting factors governing the crystal structure: the skeletal density; the size of the channels. The 2D sheets are more closely packed in the homochiral crystal than in the heterochiral crystal. However, the channels, where the counterions are accommodated, are smaller in the homochiral crystal, and the steric congestion between the anions increases with increasing anion size. The heterochiral crystal has a flexible, zigzag channel structure, and the size of the channels can increase to accommodate larger anions. Thus, complexes with large anions (i.e., ClO4- and PF6-) preferentially form heterochiral crystals rather than homochiral crystals.

DOI： 10.1021/ic070286+

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A vanadium(V)-cerium(IV) trinuclear complex, [{(VO2)-O-V(L-1)}(2)Ce-IV] (1) (H3L1: N,N'-bis-3-ethoxysalicylidene-2-hydroxy-1,3-propanediamine), was prepared by the reaction of [(VO)-O-IV(acac)(2)] and [Ce-III(acac)(3)](.)3H(2)O with H3L1 in CH3CN, followed by oxidation of the product in air. The structure of complex 1 was determined by X-ray crystal structure analysis. The complex has a V-V-Ce-IV-V-V trinuclear structure with two dioxovanadium(V) moieties on each side of the cerium(IV) moiety. Complex I has two L-1 ligands to form a trinuclear structure. The basal oxo atoms of the dioxovanadium(V) moieties are coordinated to the cerium atom with Ce-O distances of 2.322(3) and 2.343(3) angstrom. The apical two non-coordinating oxo atoms are oriented to the same direction to form an endo structure. IR data of complex 1 show V=O stretching bands at 975 cm(-1) for the apical non-coordinated oxo atoms and 802 cm(-1) for the basal coordinated oxo atoms. The cyclic voltammogram of complex I in CH3CN shows a quasi-reversible two-electron redox couple with E-1/2 = -0.60 V vs Fc/Fc(+).

DOI： 10.1246/bcsj.79.1393

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

The orange [Ru-II(H3L)](ClO4)(2)center dot 3H(2)O (1) complex was synthesized from cis-[RuCl2(dmsO)(4)] and H3L, where H3L (tris{[2-{(imidazol-4-yl)methylidene}amino]ethyl}amine) is a tripodal ligand obtained by condensation of tris(2-aminoethyl)-amine and 4-formylimidazole in a 1:3 mol ratio. The X-ray crystal structure analysis revealed that the complex has an octahedral structure coordinated by three imidazole nitrogen atoms and three Schiff base (imine) nitrogen atoms. The uncoordinated NH groups of the imidazole moieties of 1 are easily deprotonated by the action of a base. The effect of deprotonation on the Ru-III/Ru-II redox potential was studied by cyclic voltammetry in methanol containing 0.1 M LiClO4. Complete deprotonation shifts the Ru-III/Ru-II potential to a much more negative value from -0.18 to -0.72 V vs. Ag/Ag+, making it easier to oxidize. The bluish-purple Ru-III complex, [Ru-III(H3L)](3+), was formed by controlled-potential electrolysis of 1, and the electronic spectrum is reported.

DOI： 10.1002/ejic.200600111

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Dipotassium N,N'-1,2-phenylenebis(2-carbamoyl-kappa N-phenolato-kappa O]cuprate(II)), K-2[CuL], reacts with nickel(II), cobalt(II), and zinc(II) acetates, and 2,2'-bipyridine in a 1:1:2 molar ratio in methanol to yield the hetero-metal dinuclear complexes [CuLNi(bpy)(2)]. 3MeOH(1.3MeOH), [CuLCo(bpy)(2)]. 2DMF (2.2DMF), and [CuLZn(bpy)(2\)]. 1.5H(2)O (3), respectively. Crystal data for 1: P (1) over bar (No: 2) with a = 15.969(2), b = 23.494(3), c = 12.705(2) Angstrom, alpha = 92.15(1), beta = 91.652(10), gamma = 101.521(9)degrees, V = 4663(1) Angstrom(3), and Z = 4; 2, P2(1)/c (No. 14) with a = 12.604(3), b = 24.364(5), c = 13.823(2) Angstrom, beta = 94.49(1)degrees, V = 4231(1) Angstrom(3), and Z = 4. 1 and 2 have a similar discrete di-mu-phenoxo- bridged dinuclear structure, in which the Cu(II) ion assumes a square-planar geometry with the N2O2 donors atoms consisting of two amido nitrogen and two phenoxo oxygen atoms of the tetradentate ligand, and the Ni(lI) or Co(II) ion assumes an octahedral geometry with the two phenoxo oxygens of the tetradentate ligand and four nitrogen atoms from two bpy. The magnetic-susceptibility data were reproduced based on the isotropic spin Hamiltonian H = - 2JS(1).S-2 With J = - 118.0 cm(-1), (S-1, S-2) = (1/2, 1) for 1 and J = -11.0 cm(-1), (S-1, S-2) = (1/2, 3/2) for 2, respectively. When 3 was recrystallized from DMF/2-propanol, [CuLZn(bpy)](2). 2DMF (3') was obtained. The 1: 1 :1 reaction of K-2[CuL'], copper(II) acetate monohydrate, and 2,2'-bipyridine in methanol yielded [CuL'Cu(bpy)](2). 2MeOH (4), (H4L' =1,2-bis(hydroxybenzamido)-ethane). Crystal data for 3': Pbca (No. 61) with a = 19.143(2), b - 18.195(2), c = 16.832(3) Angstrom, and Z = 4; 4, P2(1)/n (No. 14) with a = 13.407(1), b = 13.172(4), c = 13.764(2) Angstrom, beta = 94.11(1)degrees, V = 2424.4(8) Angstrom(3), and Z = 4; 3' and 4 have a similar cyclic di-mu-phenoxo-mu-amido-bridged tetranuclear structure, which can be described as two di-mu-phenoxo-bridged dinuclear units bridged together by the coordination of one amido oxygen atom from each dinuclear unit to the zinc(II) or copper(II) ion of the other dinuclear unit, with Zn(1)-O(3)* = 2.004(3) and Cu(2)-O(4)* = 1.924(4) Angstrom bond distances, respectively. In the tetranuclear structure, the copper(ll) ion coordinated by the tetradentate ligand assumes a square-planar geometry and the zinc(II) or the other copper(lI) ion assumes a square-pyramidal coordination geometry with two phenoxo-oxygen atoms, two nitrogen atoms of bpy, and one amido oxygen atom. The magnetic susceptibility of 4 was reproduced by an equation derived from the H = - 2J(S-1.S-2 +S-3.S-4) - 2J'(S-2.S-3 +S-4.S-1) Spin Hamiltonian with J = - 14.6 cm(-1) and J' = -4.0 cm(-1).

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The manganese(III) complex K[MnL(py)(2)]. py (H4L = 1,2-bis(2-hydroxybenzamido)benzene, py = pyridine) reacted as a ligand complex at the two phenoxo oxygen atoms with metal(II) ion and 2,2'-bipyridine to give a series of heterometal complexes [Mn(MeOH)L(OH)M(bpy)](2) (M(II)= Zn (1); Cu (2); Ni (3); Mn(4)). X-ray structures were determined 1, C68H74N8O18Mn2Zn2: a = 12.367(3) Angstrom, b = 12.844(2) Angstrom, c = 12.262(2) Angstrom, alpha = 106.58(1)degrees, beta = 117.89(1)degrees, gamma =78.57(2)degrees, triclinic, P (1) over bar, and Z = 1. 2, C68W74N8O18Mn2Cu2: a = 13.447(1) Angstrom, b = 12.670(2) Angstrom, c = 21.732(1) Angstrom, beta = 107.076(5)degrees, monoclinic, P2(1)/n, and Z = 2. 3, C68H74N8O18Mn2Ni2: a = 12.358(3) Angstrom, b = 12.847(3) Angstrom, c = 12.315(3) Angstrom, alpha = 106.63(2)degrees, beta = 118.71(1)degrees, gamma = 78.32(2)degrees, triclinic, P (1) over bar, and Z = 1. 4, C66H66N8O16Mn4: a = 12.511(2) Angstrom, b = 21.129(3) Angstrom, c = 12.811(1) Angstrom, beta = 110.12(1)degrees, monoclinic, P2(1)/n, and Z = 2. The X-ray analyses confirmed that each of the crystals consists of an incomplete double-cubane molecule with a [Mn2M2O6] core, in which two M(II) ions are bridged by two hydroxo groups to form, a planar dinuclear moiety bridged by di-mu-hydroxo groups [(bpy)M(OH)(2)M(bpy)](2+) and the dinuclear moiety is sandwiched between two Mn(III) complexes [Mn(MeOH)L](-). The Mn(III) ion and the dinuclear M(II) moiety are triply bridged by the one hydroxo oxygen of the dinuclear moiety and two phenoxo oxygen atoms of the Mn(III) ligand complex. The two phenoxo oxygen atoms of the Mn(III) ligand complex coordinate as an axial ligand to two independent metal(II) ions of the dinuclear moiety. The magnetic susceptibilities of 1-4 were measured in the temperature range of 2-300 K. All the Mn(III) ions in these complexes are in a high-spin state of S-Mn = 2 with a d(4) electronic configuration, and the metal(II) ions are in the spin stares of S-Zn = 0, S-Cu = 1/2, S-Ni = 1, and S-Mn(II) = 1/2 (low-spin).
The magnetic susceptibility data are well reproduced by the following spin Hamiltonian based on the rhombus spin coupling model with spin (S-1, S-2, S-3, S-4) = (2, S-M, 2, S-M), including a zero-field splitting term for the Mn(III) centers: H = g(Mn)beta(S-1 + S-3). H + g(M)beta(S-2 + S-4). H - 2J(S-1. S-2 + S-2. S-3 + S-3. S-4 + S-4. S-1) - 2J'(S-2. S-4) + D-Mn[S-1z(2) + S-3z(2)], in which g(Mn) and g(M) are the g factors of the Mn(III) and M(II) ions, J and J' are the Mn(III)-M(II) and M(II)-M(II) Heisenberg coupling constants, and D is the zero-field splitting parameter of Mn(III). The calculated best-fit parameters are as follows: g(Mn) = 1.91, g(Cu) = 2.39, J = -4.5 cm(-1), J' = -8.1 cm(-1), and D-Mn = -4.9 cm(-1) for 2; g(Mn) = 1.97, g(Ni) = 2.23, J = -1.5 cm(-1), J' = -2.6 cm(-1), and D-Mn = -5.5 cm(-1) for 3; and g(Mn) = 1.95, g(Mn(II)) = 2.29, J = -3.5 cm(-1), J' = -14.1 cm(-1), and D-Mn = -12.0 cm(-1) for 4. The spin frustration due to the incomplete double-cubane structure is discussed.

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Potassium salts of cobalt(III) and manganese(III) complexes, K[CoL(py)(2)].2EtOH.MeOH 1 and K[MnL(py)(2)].py 2, have been prepared, where H4L = 1,2-bis(hydroxybenzamido)benzene and py = pyridine. 1 crystallizes in the monoclinic space group P2(1)/n with the cell dimensions of a = 12.688(3), b = 17.555(4), c = 16.673(3) Angstrom, beta = 102.59(2)degrees, V = 3624(1) Angstrom(3), and Z = 4, in which potassium ion plays a role of connector for two adjacent [CoL(py)(2)](-) molecules through K-O interaction (two phenoxo oxygen atoms of a cobalt(III) complex, two oxygen atoms of the solvent molecules, and an amido oxygen of the adjacent unit) to give an extended one-dimensional structure. 2 crystallizes in the orthorhombic space group P2(1)2(1)2(1) with the cell dimensions of a = 14.358(1), b = 16.457(2), c = 13.703(2) Angstrom, V = 3237.7(5) Angstrom(3), and Z=4, in which potassium ion plays a role of connector for three adjacent [MnL(py)(2)](-) molecules through K-O interaction to give an extended three-dimensional structure.

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

Novel two acyclic hexadentate ligands, 1,4-bis[o-(pyridine-2-carboxamidophenyl)]-1,4-dithiobutane (H(2)bpctb) and 1,4-bis[o-(pyridine-2-carboxamidophenyl)]-1,5-dithiopentane (H(2)bpctp), containing thioether functions were synthesized and their copper(II) and nickel(II) complexes [(Cu(bpctb)], 1: [Cu(bpctp)], 2; [Ni(bpctb)], 3 and [Ni(bpctp)], 4) were prepared. The structures of 1-4 were determined by X-ray crystallography. The coordination geometries of 3 and 4 are octahedral with two amido and two pyridyl nitrogen atoms and two thioether sulfur atoms of hexadentate ligand. However, the coordination geometry of 2 is a flattened tetrahedron combining two amido nitrogen atoms and two pyridyl nitrogen atoms of hexadentate ligand without thioether coordination. X-ray crystallography and ESR spectroscopic studies revealed that the coordination geometry of 1 is an uncommon equatorially elongated octahedron in solid state. However, this coordination geometry changes to an axially elongated one in solution. The copper(II/I) redox processes for 1 and 2 are around -1.2 V and the nickel(II/III) processes for 3 and 4 at around 0.3 V vs ferrocene/ferrocenium couple were observed in DMSO. (C) 1998 Elsevier Science Ltd. All rights reserved.

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Copper(II) and nickel(II) complexes with tetraanionic quadridentate ligands, K-2[CuLn] and K-2[NiLn] (n = 1, 2), have been prepared. We examined whether or not they can function as ''ligand complexes'', where H4L1 = 1,2-bis(2-hydroxy-benzamido)ethane and H4L2 = 1,2-bis(2-hydroxybenzamido)benzene. One of the ligand complexes, K-2[NiL1]. 2dmf . 2H(2)O, crystallizes in the monoclinic space group P2(1)ln with the cell dimensions of a = 15.34(8), b = 18.99(8), c = 18.86(5) Angstrom, beta = 100.2(3), V= 5406 Angstrom(3), and Z = 8. The ligand complex assumes a unique one-dimensional structure consisting of {[KO3][K(NiL1)O]}(n) as the repeating unit, where each K+ ion is surrounded octahedrally by six oxygen atoms with the distances of 2.672(2)-2.866(9) Angstrom and all the oxygen atoms act as bridging group to K+ ion. Each of the precursor complexes can function as an electrically dianionic bidentate ''ligand complex'' and reacts with Cu(II) ion and terminal capping ligand (cap) such as 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), ethylenediamine (en), and 1,3-diamino-propane (tn) to give di-mu-phenoxo-bridged dinuclear Cu(II)-Cu(II) and Ni(II)-Cu(II) complexes with the general formula of [(Cu or Ni)(LCu)-Cu-n(cap)]. The molar electrical conductivities of the dinuclear complexes measured in the DMF or DMSO solutions are essentially zero, indicating that the dinuclear structures are preserved in the solutions. The electrochemical measurements for a series of [(CuLCu)-Cu-2(cap)] (cap = bpy, phen, tn) demonstrated that the Cu(II/III) redox process of the (CuL2) site exhibits more positive potential (-0.04-0.09 V) than that of the mononuclear precursor complex (-0.288 V). One of the dinuclear complexes, [(CuLCu)-Cu-2(phen)(DMSO)], crystallizes in the orthorhombic space group Pna2(1) with the cell dimensions of a = 19.702(3), b = 15.847(3), c = 9.652(2) Angstrom, V = 3013 Angstrom(3), and Z=4. The complex consists of a discrete di-mu-phenoxo-bridged dinuclear structure, in which two copper(II) ions assume a square planar and square pyramidal coordination geometry and the bridging core of Cu2O2 is unequivalent, as found in the distances of Cu(1)-O(1)= 1.924(4) Angstrom, Cu(1)-O(2)= 1.908(4) Angstrom, Cu(2)-O(2)= 1.964(4) Angstrom and Cu(2)-O(1) =2.249(4) Angstrom. The magnetic susceptibility is well reproduced with the antiferromagnetic coupling parameter of J = -82 cm(-1) by the Bleaney-Boweres equation.

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The tetramethylammonium and potassium salts of [1,2-bis-(2-oxybenzamidato)benzene]copper(II) abbreviated as [NMe4](2)[Cu(hbab)] and K-2[Cu(hbab)] were prepared and characterized. The x-ray analysis of the potassium salt, K-2[Cu(hbab)] . 5DMF, revealed a unique one-dimensional chain structure consisting of {[KO3][K(Cu(hbab)O]}(n) as the resulting unit, where each K+ ion is surrounded octahedrally by six oxygen atoms and all the oxygen atoms play the role of a bridging group to the K+ ion. The tetramethylammonium. salt, [NMe4](2)[Cu(hbab)] . H2O, behaves as a 2:1 electrolyte in the 10(-3) mol dm(-3) solutions of methanol, acetonitrile and DMF, while the potassium salt behaves as a 2:1 electrolyte in methanol and as a 1:1 electrolyte in acetonitrile and DMF. The Cu-II/III redox potentials of the tetramethylammonium salt in DMF under the presence of 2 equivalent molar of K+, Na+, and Li+ shift to more positive values than those without alkali metal ions, where the magnitude of the positive shift increases with increasing of charge density of alkali metal ion, namely Li+ &gt; Na+ &gt; K+. The charge effect due to ion pair formation between [Cu(hbab)](2-) and Na+ or K+ causes the potential shift, while the potential shift in the case of the Lit ion is brought about by the decrease of donor ability of the phenolic oxygens, besides the charge effect. (C) 1997 Elsevier Science Ltd.

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Four copper(II) complexes with unsymmetrical quadridentate ligands involving an imidazole moiety, [CuHLⁿ]ClO₄ (1—4; n = 1—4), have been prepared and characterized, where HL¹ = N-salicylidene-N′-(2-methylimidazol-4-ylmethylidene)-1,3-propanediamine, HL² = N-salicylidene-N′-(2-phenylimidazol-4-ylmethylidene)-1,3-propanediamine, HL³ = N-acetylacetonylidene-N′-(2-methylimidazol-4-ylmethylidene)ethylenediamine, HL⁴ = N-acetylacetonylidene-N′-(2-phenylimidazol-4-ylmethylidene)ethylenediamine, respectively. The corresponding deprotonated complexes 1′—4′ were obtained when 1—4 were treated under an alkaline condition. Deprotonation of the imidazole moiety of the copper(II) complex motivates a self-assembly process which is formed by an axial coordination of the imidazolate nitrogen atom of a molecular unit to the copper(II) ion of another unit. 1′—3′ assumes a self-assembled imidazolate-bridged infinite-chain structure {Cu(II)–Im}_n in the solid state, while the polymeric species dissociates to monomeric species in the solution state. 4′ consists of a discrete deprotonated monomeric species, even in the solid state. The physical measurements, including reflectance and absorption spectra, cryomagnetic measurements, and single-crystal X-ray analyses, revealed that the self-assembly behavior for the series of copper(II) complexes depends both on the steric effect of the substituent of 2-substituted-4-formylimidazole moiety and the ligand field strength of the equatorial quadridentate ligand.

DOI： 10.1246/bcsj.70.2461

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