Crystallographic and N.M.R.-Relaxation Studies on Bis [{N,N'-(1,3-dimethylpropanediylidene)dianilinato}(1–)]nickel(II)

Abstract

A single-crystal X-ray structure determination of bis[{N,N'-(1,3-dimethylpropanediyldene)dianilinato)(1-)]nickel(II) at 295 K shows that, within each of the two independent molecules of the complex within the structure, the nickel atom is chelated by two of the bidentate ligands and is thus four-coordinate. Because of the intramolecular interactions between the phenyl substituents of the ligands, the metal atom environments are highly irregular, although consistent between the two molecules. There are no significant deviations in the Ni-N distances from the mean of 1.96₅Å; but the interligand N-Ni-N angles about the nickel range from 110.4 to 134.7º. A theoretical calculation of the ¹³C and ¹H nuclear relaxation times using the X-ray-determined metal-nuclear separations reproduces the experimentally observed relaxation times for selected positions within the complex, provided ligand-centred effects are taken into account. Mathematical complexity prevents a complete theoretical calculation of the relaxation times for ligand atoms with varying distances from the nickel atom.