The solvent path in square-planar substitutions. kinetics and mechanism for reactions of tetrachloroplatinate(II) andaquachloroplatinates(II) with halides, thiocyanate and dimethyl sulfoxide

Abstract

The kinetics for the reactions between the six complexes PtCln(H2O)−2n4−n n = 0,1,2,3,4 (including cis- and trans-isomers for n = 2) and the entering ligands Y = Cl−, Br−, I−, SCN−, and DMSO have been studied. The experiments with PtCl2−4 and trans- PtCl2(H2O)2 give the usual two-term rate constant kexp = k1 + k2[Y], when no extra chloride has been added to the solutions. The parameter k1 can be iden- tified as the acid hydrolysis rate constant for PtCl2−4 and trans-PtCl2(H2O)2, respectively. It is shown that both PtCl3H2O− and PtCl(H2O+3 are sufficiently reactive for all Y to be the intermediates in the k1- paths of these two reactions. An associative process with the solvent is therefore probable.