BROMIDE ION REPLACEMENT IN TRANS-DIBROMOTETRACYANOPLATINATE(4) AND TRANS-DIBROMOTETRANITROPLATINATE(4) IONS BY CHLORIDE ION

The first bromide replacement in the trans-PtL4Br22- (L- = CN- or NO2-) ions by chloride is catalyzed by PtL42-. The kinetics of these reactions are described by a third-order rate law with rate dependence on chloride, platinum(IV) reactant, and PtL42-. The third-order rate constants at 25.0° and μ = 1.01 M are 72 and 0.76 M-2 sec-1 for L- = CN- and NO2-, respectively. Activation parameters are reported for both reactions. The results are interpreted in terms of a bridged inner-sphere redox mechanism. The rate law for the reaction of trans-Pt(CN)4Br22- with chloride ion also contained a second-order term independent of chloride ion concentration. This result is interpreted in terms of solvent participation. © 1969, American Chemical Society. All rights reserved.