σ-Bonded organotransition-metal ions. Part VI. Kinetics and mechanism of insertion of hydrogen isocyanide in organopentacyanocobaltate(III) ions

Abstract

The 2- and 3-pyridiomethylpentacyanocobaltate(III) ions have been prepared as their potassium salts. In aqueous acidic solution (pH < 0) their conjugate acids and that of the 4-pyridiomethylpentacyanocobaltate(III) ion undergo insertion of the hydrogen isocyanide ligand between the pyridiomethyl group and the cobalt atom. The insertion product is hydrolysed further, in acid solution, to the corresponding pyridioacetic acid, but in basic solution to the corresponding pyridylacetonitrile. Analogous reactions of the methylpentacyanocobaltate(III) ion are also described. The mechanism of the insertion reactions are discussed with special reference to the relative rates of reaction of the various isomers.