STUDY OF THE NATURE OF THE INTERACTION OF CH3CN WITH LEWIS-ACIDS

The unperturbed v0 (CN) stretching frequencies of CH3CN in 18 complexes with Lewis acids are correlated with v (CN) frequencies in cobalticyanides and with cation parameters which measure sigma and pi interactions. The results indicate that the nature of the interaction is predominantly of the sigma donor-acceptor type wih no detectable pi back-donation from the cation to the CN ligand.