The magnetic and spectral properties of multinuclear transition metal complexes derived from bidentate schiff base complexes

Abstract

The synthesis and properties of a number of copper(II) complexes of the type nitrato(N-R-salicylaldimino)copper(II) (where R is an alkyl or hydroxyalkyl group) derived from bidentate Schiff base complexes of copper(II) and cupric nitrate is reported. The electronic, infra-red and E.S.R. spectra as well as the temperature dependence of the magnetic susceptibility for these compounds are given. A binuclear structure for these complexes is postulated on the basis of their magnetic properties. Added evidence for this comes from the similarity of the spectra of these compounds to those of the corresponding chloro and bromo complexes which are known to be binuclear. Both the magnetic and spectral properties of the nitrato(N-R-salicylaldimino)copper(II) complexes indicate that the structure of these compounds is best explained in terms of a trans arrangement of the R-groups with respect to the CuO2Cu skeleton and that bridging of the copper atoms occurs via the phenolic oxygen atoms, even when R is a hydroxyalkyl group. Both the nickel(II) and cobalt(II) analogues of these compounds were prepared and studied. Unlike the copper complexes, the nickel complexes are trinuclear with each nickel ion having two unpaired electrons. Two possible structures for the dinitrato[bis(bis(N-R-salicylaldimino)nickel(II))] nickel(II) complexes are suggested. The cobalt compounds form binuclear complexes similar to those formed by copper(II).