Five-coordination in some complexes of nickel(II) with Schiff bases, formed from salicylaldehydes and N,N-substituted ethylenediamines. II

Article abstract of DOI:10.1021/ic50029a004

Further studies on the complexes of nickel(II) with Schiff bases formed from ring-substituted salicylaldehydes and N,N-disubstituted ethylenediamines are presented. The compounds have a general formula [X-SALen-NR₂]₂Ni; when -NR₂ is a dimethylamino group or pyrrolidino group the ligands are tridentate and all the complexes formed from them are paramagnetic and have distorted octahedral configuration. The complexes where -NR₂ is a piperidino group are all diamagnetic and have the square-planar configuration. When -NR₂ is a diethylamino group the configuration of the complex is square-planar or octahedral depending on the substituent X, except for X = 3-Cl, 5-Cl, and 3,4-benzo when the complexes are paramagnetic and five-coordinate with μ_eff ≈ 3.3 B.M. The configuration of the five-coordinate complex most resembles that of a distorted square pyramid ; the complexes are the first reported examples of high-spin five-coordinate complexes of nickel-(II).³ Most compounds of the present study exist in solution as mixtures of planar, five-coordinate, and octahedral forms.