Synthesis, structural and spectroscopic characterization of the alpha and beta forms of bis(imidazole)copper(II) dibenzoate, [Cu(im)(2)(OBz)(2)]

Two modifications of the alpha and beta forms of bis(imidazole)copper(II) d ibenzoate, [Cu(im)(2)(OBz)(2)], have been obtained by recrystallization fro m EtOH. X-ray analysis reveals that the two modifications have the same str ucture with different geometric parameters. The a form crystallizes in the C2/c space group and the beta form, in the P2(1)/n space group. The crystal structures of both consist of centrosymmetric monomeric molecules of [Cu(i m)(2)(OBz)(2)] with a distorted octahedral geometry for the CuN2O2... O-2' chromophore. The e.s.r. spectra of the alpha and beta forms exhibit a shf s tructure that consists of 9 lines, and these signals are also different fro m those of monomeric tetra(imidazole)copper(II) diacetate. Electronic and i .r. spectra are in agreement with the structural data.