Complexes of alkyl and aryl cyanides. Part V. Tri-(2-cyanoethyl)-phosphine complexes of cobalt(II) and nickel(II) halides: the nature of the co-ordinated ligand molecules

Abstract

Nicke(II) chloride and bromide react with tri-(2-cyanoethyl)phosphine (CEP) in acetone to form the red squareplanar complexes α-NiX₂,2CEP. These complexes transform to the blue paramagnetic β-forms at room temperature and above. Cobalt(II) chloride reacts with CEP to form blue 3CoCl₂,2CEP, which contains pseudo-tetrahedral cobalt(II) and has a trimeric cage structure. The complexes 3CoX₂,2CEP,Solvent (X = Br or I; and Solvent = acetone or methyl cyanide) are also described. The nature of the co-ordinated CEP molecules is inferred from infrared spectral measurements, and the unusual donor properties of this ligand are discussed.