Redetermination of catena-poly[[chlorido(thiourea-κS)copper(I)]-μ-thiourea-κ2 S:S] at 100 K

The structure of the polymeric title compound, [CuCl(CH4N2S)2]n, has been redetermined to modern standards of precision with anisotropic refinement and location of the H atoms. The previous structure report [Spofford & Amma (1970 ▶). Acta Cryst. B26, 1474–1483] is generally confirmed to higher precision [typical Cu—S bond length s.u. values = 0.005 (old) and 0.001 Å (new)]. The asymmetric unit contains two formula units, with both CuI atoms coordinated by one terminal S atom and two bridging S atoms of thiourea ligands. This connectivity leads to polymeric [100] chains in the crystal. If very long contacts to nearby chloride ions [2.8687 (9) and 3.1394 (12) Å] are considered to be bonding, then very distorted CuS3Cl tetrahedral coordination polyhedra arise. The crystal structure is consolidated by weak intra- and inter-chain N—H⋯S and N—H⋯Cl hydrogen bonds.

The structure of the polymeric title compound, [CuCl(CH 4 N 2 S) 2 ] n , has been redetermined to modern standards of precision with anisotropic refinement and location of the H atoms. The previous structure report [Spofford & Amma (1970). Acta Cryst. B26, 1474-1483] is generally confirmed to higher precision [typical Cu-S bond length s.u. values = 0.005 (old) and 0.001 Å (new)]. The asymmetric unit contains two formula units, with both Cu I atoms coordinated by one terminal S atom and two bridging S atoms of thiourea ligands. This connectivity leads to polymeric [100] chains in the crystal. If very long contacts to nearby chloride ions [2.8687 (9) and 3.1394 (12) Å ] are considered to be bonding, then very distorted CuS 3 Cl tetrahedral coordination polyhedra arise. The crystal structure is consolidated by weak intra-and inter-chain N-HÁ Á ÁS and N-HÁ Á ÁCl hydrogen bonds.

Related literature
For the structure of a related thiourea salt, see: Zouihri (2012). For the previous structure determination of the title compound, see: Spofford & Amma (1970).
The asymmetric unit of the title compound is shown in Fig. 1. The Cu I ions have distorted tetrahedral coordination geometries formed by two bridging thiourea ligands, one terminal thiourea ligand and one chloride ion (Cu-S and Cu-Cl distances in the range of 2.2618 (10) Å to 3.1392 (12) Å) generating parallel one-dimensional polymeric chains propagating in the a axis direction.
In the crystal structure, there are two different types of hydrogen bonds (Table 1, Fig. 2). Intra-chain N-H···S and N-H···Cl interactions appear to influence the conformation of the helical chains while inter-chain N-H···S and N-H···Cl interactions crosslink the chains.
Experimental 2 mmol of CuCl 2 and 1 mmol of (Diaminomethylidene)sulfonium chloride-thiourea (3/2) [Zouihri, 2012] in 5 ml of ethanol were refluxed for 1 h, forming a colorless solution. The solution was allowed to evaporate slowly and colourless prisms were obtained after several days.

Refinement
All H atoms were located from difference Fourier maps and refined isotrpically, with restained distance N-H = 0.86 (2) A.

catena-poly[[chlorido(thiourea-κS)copper(I)]-µ-thiourea-κ 2 S:S]
Crystal data [CuCl(CH 4  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.