Kinetics and mechanism of replacement of chloride ion in trans-chloro-(o-tolyl)bis(triethylphosphine)platinum(II) by substituted pyridine compounds: influence of the basicity and steric hindrance of the pyridines on their reactivity towards the reaction intermediate

Abstract

Rates of reversible reactions between the complex trans-[Pt(PEt₃)₂(o-tolyl)Cl] and various substituted pyridine compounds has been studied in methanol at 30 °C. The strong rate dependence on the incoming group arises from competition between the incoming pyridine and leaving chloride ion for the reaction intermediate which incorporates one molecule of solvent. The efficiency of the reagent in capturing the intermediate species and the position of the equilibrium of the overall reversible reaction do not depend on the change in σ-donor ability of the pyridine compound but only on its size and steric hindrance.