Crystallographic and spectroscopic evidence of O-bonding in 3d-metal dicyanomethanidonitrite complexes

The coordination of the dicyanomethanidonitrite group through the nitroso o xygen atom in the tetrakis(pyridine) complexes [M{ONC(CN)(2)}(2)(py)(4)]. M = Ni, Co, Cu, and in the bis(pyridine) complex [Cu{ONC(CN)(2)}(2)(py)(2)] was proved by X-ray crystallography of the Ni-II complex and re-evaluated i nfrared spectra. The Ni-II and Co-II complexes exhibit almost octahedral st ructures composed of four pyridine nitrogen atoms and two oxygen atoms of d icyanomethanidonitrite ions. Both copper(II) complexes display a considerab le axial distortion of the pseudooctahedral arrangement. In the bis(pyridin e) Cu-II complex the ONC(CN)(2) groups are involved in the bridging functio n by use of the oxygen and nitrile nitrogen atoms.