Binuclear complexes of copper(II) and zinc(II) halides with bidentate and quadridentate Schiff base complexes

Abstract

Binuclear complexes of the types CuB,CuCl2, CuB,ZnCl2, ZnB,ZnCl2, and CuL2,CuCl2 have been obtained where BH2 is a quadridentate Schiff base derived from salicylaldehyde and a polyrnethylenediamine and LH is an N-alkylsalicylaldimine. The stereochemistry of the copper atoms in the binuclear complexes is inferred from comparisons of their reflectance spectra with the spectra of the simple copper complexes CuB and CuL2. The structures of the zinc complexes are discussed by reference to near ultraviolet spectra of the ligands and infrared spectra in the 1500-1560 cm-1 region. The evidence suggests that in the complexes of the type MB,M'Cl2 either but not both metal atoms may approach a tetrahedral environment. The chemistry of the complexes ZnB,ZnCl2 is complicated by the possibility of either or both zinc atoms becoming 5 coordinate by addition of solvent molecules; in some of these complexes the zinc chloride appears to be attached to a solvent molecule in a 5-coordinate Schiff base unit, rather than by bridging through phenolic oxygen atoms. The oomplexes CuL2,CuCl2 apparently have a symmetrical binuclear structure based on a trans arrangement of the Schiff base units rather than an unsymmetrical structure resembling that of the complexes CuB,CuCl2. Complexes of the types CuL2,ZnCl2 and ZnL2,ZnCl2 could not be obtained.