Dichloridobis(N,N′-diethylthiourea-κS)mercury(II)

There are two molecules in the asymmetric unit of the title compound, [HgCl2(C5H12N2S)2]. In both molecules, the N,N′-diethylthiourea ligands exhibit a cis,trans geometry around their C—N amide bonds. The shapes of the molecules are, to a large extent, determined by intramolecular N—H⋯Cl hydrogen bonds formed by the N—H groups from the cis amide groups. In one molecule, these groups are involved in three-center hydrogen bonds involving both chloride ligands, whereas in the other molecule only one Cl ligand takes part in intramolecular hydrogen bonding. The coordination around the Hg atom is distorted tetrahedral with an S2Cl2 donor set. Intermolecular hydrogen bonds between N—H groups from the trans amide units of the thioamide ligands and the chloride ligands connect the molecules into a polymeric chain extending along the c axis. One of the ethyl groups of the N,N′-diethylthiourea ligands is disordered over two positions in one of the molecules, with an occupancy of 0.654 (17) for the major component.

There are two molecules in the asymmetric unit of the title compound, [HgCl 2 (C 5 H 12 N 2 S) 2 ]. In both molecules, the N,N 0diethylthiourea ligands exhibit a cis,trans geometry around their C-N amide bonds. The shapes of the molecules are, to a large extent, determined by intramolecular N-HÁ Á ÁCl hydrogen bonds formed by the N-H groups from the cis amide groups. In one molecule, these groups are involved in three-center hydrogen bonds involving both chloride ligands, whereas in the other molecule only one Cl ligand takes part in intramolecular hydrogen bonding. The coordination around the Hg atom is distorted tetrahedral with an S 2 Cl 2 donor set. Intermolecular hydrogen bonds between N-H groups from the trans amide units of the thioamide ligands and the chloride ligands connect the molecules into a polymeric chain extending along the c axis. One of the ethyl groups of the N,N 0 -diethylthiourea ligands is disordered over two positions in one of the molecules, with an occupancy of 0.654 (17) for the major component.

Comment
We have been investigating the complexation of various thiones with d 10 metal ions in order to assess their modes of binding and to explore the related structural and spectral properties (Isab et al., 2002;Ahmad et al., 2009;Hanif et al., 2007;Mufakkar et al., 2009). Mercury(II) is a typical soft Lewis acid and shows a specific affinity to sulfur donors such as thiones. Crystal structures of several mercury(II) complexes of thiones reveal that mercury(II) coordinates with thiones through sulfur atom in a tetrahedral or pseudoterahedral environment (Ahmad et al. 2009). In continuation of our efforts to study the coordination behavior of thiones towards d 10 metal ions, we report herein the structure and synthesis of the title compound (I, Fig. 1).. The title compound consists of two molecules in the crystallographic asymmetric unit which differ from each other geometrically. In both molecules, the coordination around mercury atom is distorted tetrahedral with two S and two Cl atoms.
In one molecule, the thiocyanide groups of two diethylthiourea are oriented at a dihedral angle of 23.94 (14)°, whereas in the other its value is 31.74 (16)°. In Hg1 containing molecule, the Hg-Cl and Hg-S bond distances have values of

Experimental
To mercury(II) chloride (0.27 g, 1.0 mmol) in 10 ml of methanol was added two equivalents of N,N'-diethylthiourea in 15 ml of methanol. On mixing a clear solution was obtained that was stirred for 30 minutes. The colorless solution was filtered and the filtrate was kept at room temperature for crystallization. A white crystalline product was obtained that was washed with methanol and dried.

Refinement
The ethyl group with the atoms C7 and C8 is disordered over two positions denoted as a and b. Four restraints were imposed on the bond lengths of this group. The displacement parameters of the C7a and C7b as well as C8a and C8b were constrained to be equal. The occupancy factor of the major position refined at 0.654 (17).

supplementary materials sup-2
The H-atoms were positioned geometrically (N-H = 0.86, C-H = 0.96-0.97 Å) and refined as riding with U iso (H) = xU eq (C, N), where x = 1.5 for methyl and x = 1.2 for all other H-atoms. Fig. 1. View of the title compound with the atom numbering scheme. The displacement ellipsoids are drawn at the 30% probability level. H-atoms are shown by small circles of arbitrary radii. The dotted lines show intramolecular H-bondings. Only one position of the disordered ethyl group, the atoms C7a and C8a, is shown.