Nickel(II) and Copper(II) Complexes of C,N-Disubstituted Salicylideneimines with Steric Hindrance

Abstract

Abstract Many new nickel(II) and copper(II) complexes (abbreviated as M(X-sal.R)2) of Schiff bases were obtained from C-substituted salicylaldehydes and 2,6-dimethyl- and 2,6-diethyl-aniline, where X denotes 5-Br, 5-Cl, 5,6-benzo, 5-NO2 and 3-CH3O. For X=5-Cl, the corresponding nickel(II) complex with R=2,6-dichlorophenyl was also synthesized. All these nickel(II) complexes consist of square-planar molecules in the solid state and in non-donor solvents. The nickel (II) complexes, when dissolved in pyridine, either take up two pyridine molecules to form six-coordinated complexes or retain the original planar configuration. The configuration in pyridine depends upon the nature of X, demonstrating that the effect of X on the electronic state of the ligand may also be important, besides the steric factor, in determining the configuration of the nickel(II) complexes. The corresponding copper (II) complexes, which are square-planar in the solid state and in non-donor solvents, combine with one or two pyridine molecules, when dissolved in pyridine.