Copper(II) complexes of the bidentate Schiff-base ligand 2-(Phenyliminomethyl)pyridine and some related ligands

Abstract

A number of copper(II) complexes of anils of pyridine-2-carbaldehyde with chloride, bromide, nitrate and perchlorate as anions have been prepared. Spectral and conductivity studies suggest that the compounds may be compared with the complexes of ligands such as bipyridyl and Schiff bases derived from pyridine-2-carbaldehyde and aliphatic diamines. Physicochemical evidence is given for the stereochemistry of the compounds. Mono-, bis- and tris-chelated compounds have been obtained. Complexes of the type CuLX₂ (where X = Cl and Br) appear to be polymers with a five- or six-coordinate copper(II) stereochemistry. Evidence is presented for the existence of the five-coordinate cation [CuL₂X]⁺ (where X = Br and NO₃) in the solid compounds of type CuL₂X₂. In solution in nitromethane and methanol interaction occurs with the solvent. The bis- and tris- perchlorato compounds CuL₂(ClO₄)₂ and CuL₃(ClO₄)₂,2H₂O are described and possible structures suggested by comparison with analogous compounds.