(Thiocyanato-κS)tris(thiourea-κS)mercury(II) chloride

In the title salt, [Hg(NCS)(CH4N2S)3]Cl, the Hg2+ ion is coordinated in a severely distorted tetrahedral manner by three thiourea groups and one thiocyanate anion through their S atoms. The S—Hg—S angles vary widely from 87.39 (5) to 128.02 (4)°. Weak intramolecular N—H⋯S hydrogen bonds are observed, which form S(6) ring motifs. In the crystal, the ions are linked by N—H⋯N and weak N—H⋯Cl interactions, generating a three-dimensional network.

In the title salt, [Hg(NCS)(CH 4 N 2 S) 3 ]Cl, the Hg 2+ ion is coordinated in a severely distorted tetrahedral manner by three thiourea groups and one thiocyanate anion through their S atoms. The S-Hg-S angles vary widely from 87.39 (5) to 128.02 (4) . Weak intramolecular N-HÁ Á ÁS hydrogen bonds are observed, which form S(6) ring motifs. In the crystal, the ions are linked by N-HÁ Á ÁN and weak N-HÁ Á ÁCl interactions, generating a three-dimensional network.

Comment
This work is part of a research project concerning the investigation of thiourea (N 2 H 4 CS) and thiocyanate (SCN) based metal organic crystalline materials and their derivatives (Ramesh et al., 2012). Transition metal thiourea and thiocyanate coordination complexes are candidate materials for device applications including their nonlinear optical properties. As ligands, both thiourea and thiocyanate are interesting due to their potential formation of metalcoordination complexes as they exhibit multifunctional coordination modes due to the presence of ′S′ and ′N′ donor atoms. With reference to the hard and soft acids and bases) concept (Ozutsmi et al., 1989;Bell et al., 2001), thesoft cations show a pronounced affinity for coordination with the softer ligands, while hard cations prefer coordination with harder ligands. Several crystallographic reports about mercury(II) complexes usually consist of discrete monomeric molecules with tetrahedral (somewhat distorted) coordination environments around mercury(II) (Nawaz et al., 2010). Here, we report the synthesis and structure of the title salt, [(SC(2NH 2 )) 3 (SCN -)Hg( 2+ ] + . Cl -,(I).
In (I), the Hg 2+ ion is coordinated to three softer S atoms of thiourea and one softer S atom of a thiocyanate anion in addition to the isolated chlorine ion (Fig. 1). Intramolecular N-H···S hydrogen bonds are observed which form S(6) ring motifs (Bernstein et al., 1995). Bond distances and angles are in agreement with those reported for related compounds (Safari et al., 2009;Nawaz et al., 2010). The S-Hg-S angles vary widely from 87.39 (5) (Table.1) which form a three-dimensional network (Fig. 2).

Experimental
A mixture of thiourea, ammonium thiocyanate and mercury (II) choloride were dissolved in aqueous solution in the molar ratio 3:1:1 and thoroughly mixed for an hour to obtain a homogenous mixture. The solution was allowed to evaporate slowly at ambient temperature. Colourless single crystals suitable for single-crystal XRD were obtained in 12 days.

Refinement
All H atoms were positioned geometrically with N-H = 0.86 Å and constrained to ride on their parent atoms with U iso (H)=1.2Ueq.

Computing details
Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek,    Packing diagram of (I) viewed along the a axis. Intramolecular N-H···S hydrogen bonds and weak N-H···Cl, and N-H···N intermolecular interactions are shown as dashed lines. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.