Pulse and steady-state radiolysis studies of some homonuclear copper(II) and heteronuclear copper(II)-molybdenum(VI) peroxo compounds containing a simple peptide molecule

Abstract

The reactions of eaq−, OH·, CO2−·, and N3· radicals with some novel homo nuclear and hetero nuclear peroxo peptide complexes viz: copper peroxo glycylglycine, [Cu(O2)(H2L)2]; molybdenum oxoperoxo glycylglycine, [Mo(O)(O2)2(H2L)2]; Cu,Mo oxoperoxo glycylglycine [CuMo(O)(O2)(L)2] and Cu,Mo, oxo glycylglycine, [CuMo(O)2(L)2] (H2L=glycyl glycine) in aqueous solutions were investigated by pulse radiolysis. Three types of reactions were observed: (1) reduction of Cu(II) to Cu(I) by eaq− and CO2−·, (2) oxidation of Cu(II) to Cu(III) by N3−·, and (3) formation of a radical on H abstraction from the ligand by OH· radical. Rate constants were reported for formation and decomposition of all intermediates. In case of one electron reduced complexes of hetero atoms, CuMo(O)2L2 and CuMo(O)(O2)L2, prepared via the reduction of the corresponding complexes by eaq−, formation of a new dimer radical anion complex was observed. It is also noteworthy to mention the possibility of the effect of peroxo ligand on intermediate steps during the formation of Cu clusters. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 159–168, 1999