Synthesis and crystal structure of thiosemicarbazide complexes of nickel(II) and copper(II)

Thiosemicarbazide complexes of nickel(II) [Ni( TSC ) 2 ](H Sal ) 2 ( I ) and copper(II) [Cu( TSC ) 2 ](H Sal ) 2 ( Ia ) ( TSC is thiosemicarbazide and H Sal is a salycilate anion), as well as complexes [Ni( TSC ) 2 ](SO 4 ) · 2H 2 O ( II ) and [Ni( TSC ) 3 ]Cl 2 · H 2 O ( III) , are synthesized and characterized by IR spectroscopy and X-ray diffraction. Monoclinic crystals I and Ia are isostructural; space group P 2 1 / n, Z = 2. Crystals II are monoclinic, space group P 2 1 / m, Z = 2. Crystals III are orthorhombic, space group Pbca, Z = 8. In I and Ia , two planar salycilate anions sandwich a planar centrosymmetric [Ni( TSC ) 2 ] 2+ cation to form a supermolecule. The cation and anions are additionally bound by hydrogen bonds. Other hydrogen bonds connect supermolecules into planar layers. In structure II , centrosymmetric [Ni( TSC ) 2 ] 2+ cations are connected by π-stacking interactions into supramolecular ensembles of a specific type. The ensembles, water molecules, and (SO 4 ) 2− anions are bound in the crystal via hydrogen bonds. In the [Ni( TSC ) 3 ] 2+ cation of structure III , ligands coordinate the Ni atom by the bidentate chelate pattern with the formation of five-membered metallocycles. These metallocycles have an envelope conformation unlike those in I and II , which are planar. In III (unlike in analogous complexes), a meridional isomer of the coordination octahedron of the Ni atom is formed. Together with Cl1 − and Cl2 − anions, cations form supermolecules, which are packed into planar layers with a square-cellular structure. The layers are linked by hydrogen bonds formed by crystallization water molecules that are located between the layers.