N-Substituted salicylaldimine complexes of manganese(III). Synthesis, magnetism, and spectra

Abstract

Complexes of manganese(III) and N-substituted salicylaldimines have been prepared of general formulae Mn(sal-NR)₃ and Nn(sal-NR)₂X (X = Cl, Br, OAc). The complexes show high-spin magnetic behaviour with small deviations of the susceptibilities from the Curie law. Complexes of the type Mn(salen)X(X = Br, I) have also been studied and these show somewhat larger deviations from Curie behaviour. It is difficult to interpret this Curie-Weiss behaviour with certainty, but it can be explained for the salen derivatives, in particular, in terms of very weak antiferromagnetic interactions. The visible and near-infrared spectra for all the complexes are assigned. A Jahn-Teller splitting of the d-d transition is observed. Comparison of the i.r. spectra of the M(sal)₃ derivatives (M = Cr^III, Mn^III, and Fe^III) in the region 700-250 cm^-1 has enabled assignments of the v(M-O) modes to be made. The spectra suggest that a Jahn-Teller distortion is operative in the Mn(sal)₃ complex.