Organometallic nickel(II) complexes with substituted benzonitrile ligands, Synthesis, electrochemical studies and non-linear optical properties.: The X-ray crystal structure of [Ni(η5-C5H5){P(C6H5)3}(NCC6H4NH2)][PF6]

A new family of organometallic Ni(II) benzonitrile derivatives bearing strong donor substituents of general formula [Ni(eta(5)-C5H5){P(C6H5)(3)}NCC6H4R][PF6] (R = NH2, N(CH3)(2), C6H5, OCH3, H, F) has been synthesized. A structural study by X-ray diffraction of the compound with R = NH, showed crystallization on the centrosymmetric monoclinic space group, P2(1)/n, with a quasi planar structure of the coordinated nitrile. First and second hyperpolarizabilities evaluated by hyper-Rayleigh scattering and Maker fringe techniques showed essentially the same values for the complexes and the uncoordinated chromophores. Theoretical studies by the extended Huckel method found a small amount of pi delocalization due to the cancelling effects on the interaction of the metal fragment orbitals with pi and pi* nitrile orbitals. (C) 1998 Elsevier Science S.A.