Nucleophilic addition of methanol to nitrosodicyanomethanide in the coordination sphere of M II ions (M = Ni, Cu, Co and Pd); nitrosodicyanomethanide as an O-coordinating ligand for nickel(II)

Abstract

The systems MII-ONC(CN)2 −-L-MeOH-H2O [M = Ni, Cu, Co or Pd; L = pyrazole (pz)] were studied to determine conditions for the nucleophilic addition of MeOH to nitrosodicyanomethanide (ndcm)− in the metal coordination sphere. Compounds containing two or three bidentate anionic chelate ligands derived from methyl-2-cyano-2-(hydroxyimino)ethanimidic acid, H(mcoe), formed by nucleophilic addition of MeOH to ONC(CN)2 −, were isolated: [Cu(mcoe)2(H2O)2] (elongated pseudo-octahedron with two water molecules at long axial distances), [Co(mcoe)3] (approximate octahedron) and [Pd(mcoe)2] (square-planar). In the CoII system, oxidation to CoIII took place. In addition, simple nitrosodicyanomethanide compounds [Ni(ndcm)2(pz)4] (nearly octahedral) and [Pd(ndcm)2(pz)2] (square-planar) were obtained. The crystal structure of trans-[Ni(ndcm)2(pz)4] has been elucidated by X-ray crystallography. The NiII atom is nearly octahedrally coordinated by four nitrogens of pz and two oxygens of (ndcm)−. This compound is the first example of a transition metal oxygen-coordinated nitrosodicyanomethanide complex with a short metal-oxygen bond. The remaining compounds were characterized by i.r. and electronic spectra.