Crystal structure of bis­(tetra­methyl­thio­urea-κS)bis­(thio­cyanato-κN)nickel(II)

In the course of our investigations regarding transition-metal thio­cyanates with thio­urea derivatives, the title compound, [Ni(NCS)2(C5H12N2S)2], was obtained. The asymmetric unit consists of one thio­cyanate anion and one tetra­methyl­thio­urea mol­ecule on general positions, as well as one NiII cation that is located on a twofold rotational axis. In this compound, discrete complexes are formed in which the NiII cations are surrounded by two trans-N-bonding thio­cyanate anions as well as two trans-S-bonding tetra­methyl­thio­urea mol­ecules within a distorted square-planar coordination geometry. The discrete complexes are linked by pairs of weak C—H⋯S hydrogen bonds between the thio­cyanate S and one of the tetra­methyl­thio­urea methyl hydrogen atoms into chains along the crystallographic a- and c-axis directions, which are combined into layers parallel to the ac plane. X-ray powder diffraction proves that a pure crystalline phase was obtained and measurements using thermogravimetry and differential thermoanalysis reveal that the compound decomposes at about 408 K, where all tetra­methyl­thio­urea mol­ecules are lost.