Synthesis and crystal structure of hydrated cation-anion nickel(II) thiosemicarbazide and nickel(II) malonate dihydrate complex

A crystal of Ni(HL)2[Ni(Malon)2(H2O)2]2 · 3.51H2O (I), which is built of [Ni(HL)2]2+ cations (HL is thiosemicarbazide), [Ni(Malon)2(H2O)2]2− anions (H2 Malon is malonic acid), and molecules of crystal water, has been synthesized and studied by IR spectroscopy, thermogravimetry, and X-ray diffraction. Structural units of complex I are linked by electrostatic interactions and numerous hydrogen bonds. The unit cell parameters b = 7.233(1) Å, c = 24.426(5) Å, β = 127.98(3)°, space group C2/c, Z = 8. The polyhedron of the nickel atom in [Ni(HL)2]2+ cations is a cis-square that is slightly distorted within ∼10°. Ligands HL are bidentately chelately coordinated (via N and S) to the nickel atom with the closure of near planar five-membered chelate rings. The malonate groups in [Ni(Malon)2(H2O)2]2− anions are bidentately chelately coordinated with the formation of six-membered non-planar chelate rings. The coordination of the central atom is complemented to an octahedron with two H2O molecules. The bond lengths in cations are 1.924(4) and 1.912(4) Å (Ni-N) and 2.144(1) and 2.150(2) Å (Ni-S), and the bond lengths in anions are 2.003–2.046(3) Å (Ni-O) and 2.113(4) and 2.122(3) Å (Ni-O(w)).