Cobalt(III) compounds of carbanions and their reactivity. Part I. The preparations and structure of some malononitrilato-compounds

Abstract

Malononitrile(mnH) reacts with a variety of cobalt(III) compounds of planar quadridentate dianion Schiff-base ligands to produce cobalt alkyls of the type [Co(quadridentate)(mn)(L)](where L is a neutral unidentate ligand). A range of solid compounds has been isolated and six-co-ordinate structures are assigned to most of them on the basis of the electronic spectra, although several may be five-co-ordinate. ¹H N.m.r. data are recorded for solutions in C₅D₅N and (CD₃)₂SO. The formation reaction appears to involve carbanion nucleophilic substitution at a cobalt(III) centre. The compounds undergo further reaction in pyridine to produce cyano-species of the type [Co(quadridentate)(CN)(py)].