Cobalt(II) Cyanides in Aprotic Media: Effect of Varying Counterion and Solvent

Abstract

A spectroscopic, synthetic, and X-ray diffraction study of the species present in Co(II)-cyanide mixtures in polar aprotic solvents (acetonitrile, dimethylformamide) as a function of Co:CN ratio, counterion, and concentration is presented. Evidence is offered for the existence of species containing one to five cyanide ligands per cobalt, in some cases with additional coordinated solvent. Syntheses are reported for Li3[Co(CN)5]•3DMF and (PNP)2[Co(CN)4], as well as full details of the single-crystal X-ray structure determination of the last compound. Counterion effects on the stability of the species present in the Co(II)-CN system in aprotic solvents and on the reactivity of pentacyanocobaltate(II) in alkenyl halide cyanation are described. The nature of the decomposition pathways of the Co(II)-CN system is discussed. © 1986, American Chemical Society. All rights reserved.