Complexes of nickel (II) with Schiff bases formed from salicylaldehydes and N-substituted ethylenediamines. I

Article abstract of DOI:10.1021/ic50028a010

Schiff bases formed from ring-substituted salicyclaldehydes and N-substituted ethylenediamines form four types of complex with nickel(II) with a general formula [X-SALen-N(R)R′]₂Ni. When R = H, R′ = n-alkyl, benzyl, the ligands are tridentate and their nickel complexes are six-coordinate, octahedral, and mononuclear both in the solid state and in noncoordinating solvents. They do not form adducts with pyridine. When R = H, R′ = ortho-substituted phenyl, the complexes are all square-planar and diamagnetic. When R′ = phenyl or para-substituted phenyl the complexes are either square-planar or octahedral depending on the ring substituent X. In inert solvents compounds with any substituted N-phenyl group exist as octahedral and square-planar forms in equilibrium, with a greater proportion of the square-planar form at higher temperatures. In pyridine the compounds are converted into octahedral pyridine adducts. When R = phenyl, R′ = methyl, phenyl, these Schiff bases function as bidentate ligands and form trans-planar complexes both in the solid state and in inert solvents, and the complexes form adducts with pyridine.