Thiocyanate and Dicyanamide Anion Controlled Nuclearity in Mn, Co, Ni, Cu, and Zn Metal Complexes with Hemilabile Ligand 2-Benzoylpyridine

Two pseudohalides thiocyanate and dicyanamide have been employed to synthesize complexes of Mn II, Co II, Ni II, Cu II, and Zn II in the presence of a hemilabile ligand 2-benzoylpyridine (Phpyk). With thiocyanate all the aforesaid metal ions (except for Co II, of which suitable single crystals for X-ray analysis were not obtained) produce mononuclear complexes having general composition of [M II (NCS) 2 (Phpyk) 2 ]. The structure determination reveals that Mn and Zn complexes ( 1, 4 ) are isomorphous and isostructural (crystallizing in space group C 2/c), while Ni and Cu complexes ( 2, 3 ) crystallize in space groups P 1̅ and P 2 1 / n, respectively. Interestingly, no complex has been obtained with a configuration having the N of one Phpyk trans to the O of the other chelating ligand and among the four complexes only in complex 3 the two thiocyanato ligands are in trans -configuration. On the other hand, complexes 5 – 8 are isomorphous and crystallize in orthorhombic chiral space group P 2 1 2 1 2 1 . The bridging mode of dicyanamide anions helps to generate a three-dimensional covalently bonded polymeric network of 6 6 topology for all the polynuclear complexes. By using 8 as sole precursor, we have pyrolytically synthesized triangular shaped ZnO nanoparticles.