SYNTHESIS, PROPERTIES AND CRYSTAL-STRUCTURE OF BIS(METIAMIDE)BIS(ISOTHIOCYANATO)NICKEL(II)

The crystal structure of Ni(metiamide)2(NCS) 2 was determined by X-ray diffraction methods. Unlike cimetidine, which is a tridentate ligand, metiamide (C9H16N4S2): N-Methyl-N-[2-{(5-methylimidazol-4-yl)methylthio}ethyl]thiourea (which also possesses three potential donor sites) is bidentate, coordinated to the nickel atom through N(imidazole) and S(thioether) atoms. The S(thiourea) atom does not take part in the coordination; instead, the isothiocyanate ion is coordinated through nitrogen to the metal atom. The nickel atom lies on a centre of symmetry in an elongated octahedral environment: the nitrogen atoms occupy equatorial positions (Ni - N = 2.04 and 2.06 angstrom) and S(thioether) atoms occupy apical positions (Ni - S = 2.58 angstrom). Individual molecules are linked together by a unique S ... H - N hydrogen bond involving the uncoordinated S(thiourea) atom. IR, electronic reflectance and magnetic data are consistent with the structural results.