σ-Bonded organotransition-metal ions. Part VII. Kinetics and mechanism of the acid- and base-catalysed decomposition of the secondary α-(2-pyridio)ethylpentacyanocobaltate(III) ion

Abstract

The air-stable secondary α-(2-pyridio)ethylpentacyanocobaltate(III) ion has been prepared in aqueous solution. The kinetics and products of its decomposition have been studied in from 9M-perchloric acid to 0·1 M-sodium hydroxide. Four distinct modes of decomposition have been detected. In alkaline solution 2-vinylpyridine and hydridopentacyanocobaltate(III) ion are formed reversibly. In solutions of intermediate pH (0–6), a multistage reaction involving initial loss of a cyanide ligand is believed to take place. In 1–5M perchloric acid a one-proton-catalysed insertion of a hydrogen isocyanide ligand occurs and in stronger acid a two-proton-catalysed insertion of a hydrogen isocyanide ligand also occurs. The mechanisms of these reactions are discussed.