X-band electron paramagnetic resonance spectra of imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes of glycylvaline

X-band EPR spectra of imidazolate-bridged [(glyval)Cu-im-Cu-(glyval)Na and [(glyval)Cu-im-Zn(glyval)]Na,where glyval = glycylvaline, im = imidozolate ion, are described. The EPR and electronic spectra of related mononuclear complexes viz., aquoglycylvalinato copper(II) and imidazole glycylvalinato copper(II) are also described. A pH dependent EPR study of frozen 50% aqueous DMSO solution of [(glyval)Cu-im-Zn(glyval)]Na suggest that the complex is stable in PH range (7.15-9.5). At lower pH (< 7.15), the imidazolate bridge breaks on the zinc side with decreasing pH value.