Faculty Profiles - SUNATSUKI Yukinari

Papers - SUNATSUKI Yukinari

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Spin states of mono- and dinuclear iron(II) complexes with bis(imidazolylimine) ligands

Kunihiro Fujita, Ryohei Kawamoto, Ryohei Tsubouchi, Yukinari Sunatsuki, Masaaki Kojima, Seiichiro Iijima, Naohide Matsumoto

CHEMISTRY LETTERS 36 ( 10 ) 1284 - 1285 2007.10

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

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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Chiral recognition and conglomerate crystallization induced by self-organization of cobalt(III) complexes of a tripodal ligand containing three imidazole groups

Hirofumi Nakamura, Yukinari Sunatsuki, Masaaki Kojima, Naohide Matsumoto

INORGANIC CHEMISTRY 46 ( 20 ) 8170 - 8181 2007.10

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

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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Synthesis and structures of vanadium-cerium trinuclear complexes with Schiff-base ligands

Masanobu Tsuchimoto, Toshio Ishii, Takane Imaoka, Kimihisa Yamamoto, Naoki Yoshioka, Yukinari Sunatsuki

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 79 ( 9 ) 1393 - 1397 2006.9

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

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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A ruthenium(II) complex with a tripodal ligand containing three imidazole groups

Tomoka Yamaguchi, Kazutoshi Harada, Yukinari Sunatsuki, Masaaki Kojima, Kiyohiko Nakajima, Naohide Matsumoto

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY ( 16 ) 3236 - 3243 2006.8

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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Potential and pH Dependencies of Adsorbed Species of 2-, 4-Pyridinethiol and 2-Pyrimidinethiol on Au(111) Electrode

Isao Taniguchi, Soichiro Yoshimoto, Yukinari Sunatsuki, Katsuhiko Nlshiyama

Electrochemistry 67 ( 12 ) 1197 - 1199 1999

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

Potential and pH dependencies of surface structures of Au(111) electrodes modified with 2- and 4-pyridinethiol (2-PySH and 4-PySH, respectively) and 2-pyrimidinethiol (2-PymSH) were examined by surface-enhanced IR absorption spectroscopy (SEIRAS) and STM. At positive potentials, the pKa values of the adsorbed pyridinethiol and pyrimidine species decreased, even in an acid solution the pyridine (or pyrimidine) N atom became less protonated. Therefore, STM images of self-assembled monolayers of these thiols observed at properly positive potentials (e.g.,&gt
ca. 0.3 V vs. Ag/AgCl for 2-PySH and 2-PymSH in a 0.1 M HClO4 solution, &gt
0.7 V vs. Ag/ AgCl for 4-PySH in a 0.01 M (M = mol dm-3) HClO4 solution) can be used for evaluating the structures in a neutral solution.

DOI： 10.5796/electrochemistry.67.1197

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Synthesis, structure, and properties of di-mu-phenoxo-bridged dinuclear (CuNiII)-Ni-II and (CuCoII)-Co-II complexes and cyclic di-mu-phenoxo-mu-amido-bridged tetranuclear (Cu2Zn2II)-Zn-II and Cu-4(II) complexes derived from the 1,2-bis(2-oxidobenzamidato)benzenecuprate(II) dianionic ligand-complex Reviewed

Y Sunatsuki, T Matsuo, M Nakamura, F Kai, N Matsumoto, JP Tuchagues

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 71 ( 11 ) 2611 - 2619 1998.11

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

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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Synthesis, magnetic properties, and incomplete double-cubane structure of Manganese(III)-metal(II) complexes [Mn(MeOH)L(OH)M(bpy)](2) (M = Zn, Cu, Ni, and Mn; H4L = 1,2-bis(2-hydroxybenzamido)benzene; bpy = 2,2 '-bipyridine) Reviewed

Y Sunatsuki, H Shimada, T Matsuo, M Nakamura, F Kai, N Matsumoto, N Re

INORGANIC CHEMISTRY 37 ( 21 ) 5566 - 5574 1998.10

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

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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Multi-dimensional structures constructed by the electrostatic interaction of potassium salts of cobalt(III) and manganese(III) complexes with 1,2-bis(2-hydroxybenzamido)benzene Reviewed

Y Sunatsuki, M Mimura, H Shimada, F Kai, N Matsumoto

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 71 ( 1 ) 167 - 173 1998.1

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

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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Synthesis, crystal structures and electrochemical properties of Cu-II and Ni-II complexes with hexadentate ligands containing thioether-amidopyridyl donor set Reviewed

Y Sunatsuki, T Matsumoto, Y Fukushima, M Mimura, M Hirohata, N Matsumoto, F Kai

POLYHEDRON 17 ( 11-12 ) 1943 - 1952 1998

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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Dinaionic ligand complexes, K-2[CuLn] and K-2[NiLn] (n=1,2; H4L1=1,2-bis(2-hydroxybenzamido)ethane, H4L2=1,2-bis(2-hydroxybenzamido)benzene), and their dinuclear Cu(II)-Cu(II) and Ni(II)-Cu(II) complexes Reviewed

Y Sunatsuki, M Nakamura, N Matsumoto, F Kai

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 70 ( 8 ) 1851 - 1858 1997.8

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

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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Crystal structure and electrochemical properties of Cu-II complexes with 1,2-bis(2-hydroxybenzamido)benzene Reviewed

Y Sunatsuki, R Hirata, Y Motoda, M Nakamura, N Matsumoto, F Kai

POLYHEDRON 16 ( 23 ) 4105 - 4111 1997

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

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+ > Na+ > 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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Steric-Hindrance Effect of a Substituent in the Self-Assembly Process of Copper(II) Complexes with Quadridentate Schiff-Base Ligands Involving a 2-Substituted-Imidazole Moiety Reviewed

Naohide Matsumoto, Masaaki Mimura, Yukinari Sunatsuki, Shingo Eguchi, Yukiko Mizuguchi, Hitoshi Miyasaka, Toshio Nakashima

Bull. Chem. Soc. Jpn. 70 ( 10 ) 2461 - 2472 1997

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

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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