Heptacoordination in Mn-II, Ni-II, and Cu-II complexes of 2,6-diacetylpyridine bis(acetylhydrazone)

Manganese(II), nickel(II), and copper(II) complexes of 2,5-diacetylpyridine bis (acetylhydrazone) (H(2)dapac) have been synthesized and structurally characterized by X-ray diffraction methods. [Mn(H(2)dapac)(OH2)(2)](NO3)(2) crystallizes in the monoclinic space group P2(1)/c with a = 11.145(3), b = 10.723(4), c = 17.189(2)Angstrom, beta = 92.81(2)degrees and Z = 4; [Ni(H(2)dapac)(OH2)(2)](NO3)(2) . H2O crystallizes in the monoclinic space group P2(1) with a = 9.994(3), b = 14.423(4), 7.697(2)Angstrom, beta = 100.37(2)degrees, and Z = 2; [Cu(H(2)dapac)(OH2)(2)](NO3)(2) . H2O crystallizes in the orthorhombic space group Pbcn with a = 20.986(5), b = 14.552(3), c = 6.905(1)Angstrom and Z = 4. In each case the metal atom has a slightly distorted pentagonal bipyramidal environment, the equatorial positions being occupied by three nitrogen and two oxygen atoms from the hydrazone ligand and the apices by two water molecules. The crystalline cohesion in ensured by a three-dimensional network of hydrogen bonds involving the complex cations, the nitrate anions, and, where present, the uncoordinate water molecules.