EPR study of an imidazolate-bridged Cu-Zn complex of glycylglycine

An imidazolate-bridged heterometallic binuclear copper-zinc complex Na[(gly gly)Cu-im-Zn(glygly)], where H(2)glygly is glycylglycine and imH is imidazo le, has been synthesized. X-band e.p.r. spectra of the complex at different pH values in frozen solution (50% DMSO, 77 K) suggest that the imidazolate bridged complex is stable in the pH range 7-10. At lower pH (< 7) the imid azolate bridge breaks on the copper side. At higher pH (> 10), the e.p.r, c hanges suggest either hydroxylation of the copper centre or breaking of the imidazolate bridge on the zinc side. (C) 1998 Elsevier Science Inc, All ri ghts reserved.