The Tetrakis(trimethylphosphine)cobalt Anion

Abstract

Reduction of paramagnetic L4Co (L = (CH3)3P) (d9) by alkali metals affords salts of L4Co- (d10). These are strong reducing agents, powerful bases and very able nucleophiles. They rapidly exchange three of their phosphine ligands for CO. Their reactions with a variety of inorganic and organic halides are shown to be effectively oxidative additions. From the distinct thermochromic behaviour of these salts both in the solid state and in solution a reversible formation involving different states of solvation is deduced.