Novel trinuclear copper(II) complexes with alpha,beta-unsaturated carboxylates and imidazole

A MeOH solution of imidazole reacts with Cu(2)A(4)(H2O)(2) [A = CH2=CHCO2-, CH2=C(Me)CO2-] to yield novel trinuclear copper(II) carboxylate complexes of general formula: Cu(3)A(5)(OH)(imH)(3) [(1) A=CH2=CHCO2-; (2) A = CH2=C(Me)CO2-; imH = imidazole]. The crystal structure of (2) has been determined. The geometry of one copper(II) atom is distorted trigonal bipyramidal, and the other two copper(II) atoms are distorted square-planar. The i.r. spectra show the presence of the absorption bands of both bidentate mu(2)-O,O' and monodentate carboxylate ligands. The electronic reflectance spectra in the solid state suggest that the d-d transitions of complexes are in a trigonal bipyramidal ligand field and a square-planar ligand field. Room temperature X-band e.s.r. spectra of powdered samples with g(av) = 2.140 for (1) and g(av) = 2.092 for (2), indicate that there is no spin coupling between the copper(II) atoms.