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

Thiosemicarbazide complexes of nickel(II) [Ni(TSC)2](HSal)2 (I) and copper(II) [Cu(TSC)2](HSal)2 (Ia) (TSC is thiosemicarbazide and HSal is a salycilate anion), as well as complexes [Ni(TSC)2](SO4) · 2H2O (II) and [Ni(TSC)3]Cl2 · H2O (III), are synthesized and characterized by IR spectroscopy and X-ray diffraction. Monoclinic crystals I and Ia are isostructural; space group P21/n, Z = 2. Crystals II are monoclinic, space group P21/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 (SO4)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.