Stopped-flow spectrophotometric study on the reactions between copper(II) ions and some dithiophosphates

Kinetic studies on the reaction of copper(II) with some dithiophosphates ((RO)(2)PS2- = dtp, where R = Me, Et, i-Pr) in mixed water-alcohol solutions were performed using stopped-flow spectrophotometric technique. A short-lived species with an absorption maximum at 420 nm is observed, which reaches its maximal concentration at the ratio Cu(II)/dtp = 1:2 and decays within few seconds through a second-order reaction in respect to its concentration. The bis(chelate)Cu(II) complex is found to be the intermediate, on the ground of its spectral features. The mechanism by which the bis-(chelate)Cu(II) complex obtained is subject to a further self-redox process of inner disproportionation, yielding the corresponding complex of Cu(I) and a disulphide, is confirmed. (C) 1998 Elsevier Science S.A. All rights reserved.