CATALYTIC ACTIVITIES OF THE ANTITUMOR COMPLEX BIS(ACETATO)BIS(IMIDAZOLE)COPPER(II) AND BIS(VALPROATO)BIS(IMIDAZOLE) COPPER(II) FOR THE OXIDATION OF ORGANIC SUBSTRATES

The catalytic activities of the antitumour complex bis(acetate) bis(im idazole) copper(II) (1) and bis(valproato)bis(imidazole)copper(II) (2) toward the aerobic oxidation of N, N,N',N'-tetramethyl-p-phenylenedia mine (TMPD) to TMPD(+) and 3,5-di-t-butylcatechol (DTBC) to 3, 5-di-t- butyl-o-benzo quinone were determined. The rates were found to be firs t order with respect to both substrate and catalyst concentration. Com plexes 1 and 2 were found to be effective catalysts for the oxidation cyclization of o-phenylenediamine (OPD) to 2,3-diaminophenazine, as we ll as oxidation of hydroquinone to 1,4-benzoquinone. The formation of a copper ion semiquinone species in solution, which may be the catalyt ic intermediate that reacts directly with oxygen, was demonstrated spe ctrophotometrically. The results suggested that the oxidation of OPD a nd DTBC takes place in two one-electron transfer steps. The copper(II) complex/OPD/PPh(3) catalyst system was found to catalyse the oxidatio n of triphenylphosphine (PPh(3)) to Ph(3)P=O by molecular oxygen. The relevance of these copper(II) complexes to the biological functions of copper-containing proteins are discussed.