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A novel μ-pyrazolato-μ-hydroxo-dibridged copper(II) complex has been synthezised and structurally characterized: [{Cu(mepirizole)Br}[sub2](μ-OH)(μ-pz)} (mepirizole = 4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine; pz = pyrazolate). The title compound crystallizes in the monoclinic system, space group P2[sub1]/c[sub1], with a = 15.618(2) Å, b = 15.369(3) Å, c = 16.071 (3) Å, and β = 112.250(1)°. The structure is built up of dinuclear [{Cu(mepirizole)Br}[sub2](μ-OH)(μ-pz)] units with five-coordinated copper(II) ions (CuBrN[sub3]O chromophores) linked by μ[sub2]-OH and μ[sub2]-pyrazolato bridges that are well separated from each others. The intramolecular copper-copper distance is 3.378(3) Å. Magnetic susceptibility data show that the copper atoms are strongly antiferromagnetically coupled with J = -770 cm[sup-1]. The obtained triplet-singlet energy gap is compared with those reported for a series of related dimers. The strong antiferromagnetic coupling arising from the complementarity of the hydroxo and pyrazolato bridges has been discussed on the basis of DFT calculations. [ABSTRACT FROM AUTHOR]

The preparation and characterization of tris-complexes of Mn, Co, Ni, Cu and Zn with a new pyridylhydrazone, 2-pyridylcarbaldehyde- N, N-dimethylhydrazone (pch), are described. In all the complexes pch behaves as a bidentate ligand binding through the pyridine and azomethyne nitrogen atoms. The complexes appear to be monomeric, high spin six-coordinate, and a distorted octahedral stereochemistry around the metal is suggested. The e.p.r. results for both Cu compounds indicate a mainly d−y ground state with a static Jahn-Teller distortion, whilst for the Mn complex the e.p.r. data indicates a very low symmetry for the MnN polyhedron. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis, X-ray structure and magnetic characterization of [Cu2(HBIMAM)2(C4O4)3(H2O)2] n ·2nH2O [BIMAM=bis(imidazol-2-yl)methylamino methane]. This compound is made of infinite chains – running along the [110] direction – with copper ions bridged by μ1,3-squarato ligands. Furthermore, these chains are further cross-linked through additional squarate anions (with the same μ1,3-bis(monodentate) bridging mode) to generate two-dimensional sheets parallel to the ab plane. There are inter-chains links every two copper atoms in a chain, forming an unusual (3×2) oblique copper(II) grid. Magnetic susceptibility measurements in the range 2–300K show weak antiferromagnetic exchange interactions. A detailed analysis of the structure shows that the more appropriate model to be used to reproduce the magnetic properties is a regular S =1/2 antiferromagnetic chain model including an inter-chain interaction (j′). Finally, the observed magnetic behavior (J chain =−0.97(1)cm−1 and j′=−0.03(1)cm−1) is compared with that observed in related hexacoordinated copper(II) compounds containing μ1,3-squarato bridges. [ABSTRACT FROM AUTHOR]

Abstract: Two new Cu(II) complexes with bis(2-imidazolyl) (bis(methoxycarbonyl)methylmethane) (BIBM), a tridentate bis(imidazole) based ligand with the formula [Cu(BIBM)2](ClO4)2 (1) and [{Cu(BIBM)(H2O)}2(μ1,2,3,4-C2O4)](C4O4)·6H2O (2) have been synthesized and characterized. Compound 1 shows mononuclear cationic [Cu(BIBM)2]2+ units and perchlorate ions. The coordination around the Cu(II) ion shows a tetragonally-elongated octahedral geometry. The BIBM ligand acts as a k 3-N,N’,O tripodal ligand, through two imidazole N atoms and a weak Cu–O(carboxymethyl) axial interaction. In the crystal structure cations and anions connect through H-bonds generating linear chains. Linear chains assemble forming molecular layers through imidazole rings aromatic–aromatic interactions. The structure of compound 2 consists on centrosymmetric oxalate-bridged binuclear [Cu2(BIBM)2(OH2)2(μ1,2,3,4-C2O4)]2+ units, squarate dianions and water molecules in a 1:1:6 relation. The geometry around copper ions could be described as tetragonally elongated octahedrons of the 4+1+1′ type. In the structure, molecular building blocks (MBBs) are packed together by multiple-path H-bonding and π–π stacking interactions, giving rise to the supramolecular 3D network. The molecular EPR spectra is indicative of an essentially ground state for copper(II) ions in both compounds. Magnetic susceptibility measurements of compound 2 show strong antiferromagnetic exchange between the copper(II) ions (J =−325cm−1). The magnitude of the exchange interaction is discussed in relation to the structural features and compared with published magneto-structural data on similar oxalato-bridged copper(II) compounds. [Copyright &y& Elsevier]

A novel mu-pyrazolato-mu-hydroxo-dibridged copper(II) complex has been synthesized and structurally characterized: [(Cu(mepirizole)Br)2(mu-OH)(mu-pz)] (mepirizole=4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine; pz=pyrazolate). The title compound crystallizes in the monoclinic system, space group P2(1)/c, with a=15.618(2) A, b=15.369(3) A, c=16.071(3) A, and beta=112.250(1) degrees. The structure is built up of dinuclear [(Cu(mepirizole)Br)2(mu-OH)(mu-pz)] units with five-coordinated copper(II) ions (CuBrN3O chromophores) linked by mu2-OH and mu2-pyrazolato bridges that are well separated from each others. The intramolecular copper-copper distance is 3.378(3) A. Magnetic susceptibility data show that the copper atoms are strongly antiferromagnetically coupled with J=-770 cm(-1). The obtained triplet-singlet energy gap is compared with those reported for a series of related dimers. The strong antiferromagnetic coupling arising from the complementarity of the hydroxo and pyrazolato bridges has been discussed on the basis of DFT calculations.