The X-ray structures of a series of copper(II) complexes with tetradentate Schiff base ligands derived from salicylaldehyde and polymethylenediamines of varying chain length

Abstract

The structures of six N, N′-polymethylene-bis(salicylaldiminato)copper(II) Schiff base complexes with alkyl backbones ranging from two to eight carbons have been determined by X-ray crystallography. The complexes are monomeric when the alkyl chain length is relatively short (two, three, and four CH 2 groups) but are dimers when the chain length becomes longer (five, six, and eight CH 2 groups). There is a regular increase in the distortion about the copper center as the alkyl chain length approaches four and five carbons, followed by a decrease as the chains become longer. Previously noted trends in electronic spectral, magnetic susceptibility, and microwave dielectric loss data can be accounted for based on this structural information.