Cyanamidonitrate-nickel(II) and -cobalt(II) complexes of imidazole ligands: X-ray crystallography and spectroscopic investigation

New cyanamidonitrate complexes with imidazole (iz) and its methyl derivativ es (meiz) of the type [M(NO2NCN)(2)L-4] (with M = Ni, L = iz, 1-, 2-, 4-mei z; M = Co, L = iz, 1-, 4-meiz) and [CoL4] (NO2NCN)(2) (with L = iz, 2-meiz) have been prepared and characterized by spectroscopic methods. The crystal structures of [Ni(NO2NCN)(2)(1-meiz)(4)] and [Co(NO2NCN)(2)(iz)(4)] have b een determined by X-ray crystallography. The metal(II) environment is pract ically octahedral, composed of four tertiary nitrogens from imidazole ligan ds and two nitrile nitrogens from cyanamidonitrate groups. According to the spectral results, similar molecular structures can be assumed for all rema ining [M(NO2NCN)(2)L-4] compounds. On the other hand, compounds [CoL4] (NO2 NCN)(2) consist of tetrahedral complex cations [CoL4](2+) which are electro statically attracted with NO2NCN-. An isomeric pair, [Co(NO2NCN)(2)(iz)(4)] and [Co(iz)(4)](NO2NCN)(2), of octahedral and tetrahedral structure, respe ctively, were characterized. (C) 2000 Elsevier Science Ltd All rights reser ved.