6533b85afe1ef96bd12b959e

RESEARCH PRODUCT

Mononuclear and binuclear copper(II) complexes with bis(2-imidazolyl)(bis(methoxycarbonyl)methylmethane) (BIBM), a tripodal bis(imidazole) based ligand. Synthesis, crystal structure and magnetic Characterization of [Cu(BIBM)2](ClO4)2 and [{Cu(BIBM)(H2O)}2(μ1,2,3,4-C2O4)](C4O4)·6H2O

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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 ](ClO 4 ) 2 ( 1 ) and [{Cu(BIBM)(H 2 O)} 2 (μ 1,2,3,4 -C 2 O 4 )](C 4 O 4 )·6H 2 O ( 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 [Cu 2 (BIBM) 2 (OH 2 ) 2 (μ 1,2,3,4 -C 2 O 4 )] 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 d x 2 -y 2 d x 2 - y 2 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  = −325 cm −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.