Experimental and DFT study of the kinetics of the interaction of Pt(II) and Pd(II) with disulfides in hydrochloric acid solutions

Abstract

In this paper, the kinetics and mechanistic studies of the kinetics of the interaction of [PtCl4]2− and [PdCl4]2− with cystine, cystamine, homocystine, and dithiodipropionic acid have been reported. The direction of the reaction primarily depends on the nature of the metal. The rate-limiting step for the interaction [PtCl4]2− with cystine and dithiodipropionic acid is the formation of S,S-binuclear disulfide platinum complex [Pt2Cl6(R-SS-R)]; for cystamine is the formation of S-disulfide platinum complex [PtCl3(R-SS-R)]; and for homocystine is the formation of the platinum(IV) thiol complex [PtCl4(S-R)2]. The rate-limiting step for the interaction [PdCl4]2− with cystine is the formation of S,S-binuclear disulfide platinum complex [Pd2Cl6(R-SS-R)]; for homocystine is the formation of S-disulfide platinum complex [PdCl3(R-SS-R)]; for cystamine, the rate-limiting step are represented by the contributions of the formation of both mono and binuclear disulfide complexes; and for dithiodipropionic acid is the hydrolysis of the binuclear S,S′-disulfide palladium complex.