Crystal structure of chlorido[1-(4-nitrophenyl)thiourea-κS]bis(triphenylphosphane-κP)copper(I)

The mononuclear title complex contains a chloride, a 1-(4-nitrophenyl)thiourea and two triphenylphosphane ligands, leading to a tetrahedrally arranged ClP2S coordination set. N—H⋯Cl and C—H⋯O hydrogen bonds connect the molecules into a three-dimensional network.

The mononuclear mixed-ligand title complex, [CuCl(C 7 H 7 N 3 O 2 S)(C 18 H 15 P) 2 ], displays a distorted tetrahedral coordination sphere around the Cu I atom, with two P atoms from two triphenylphosphane molecules, one terminal S atom from a 1-(4-nitrophenyl)thiourea molecule and a chloride ion as ligands. An intramolecular N-HÁ Á ÁCl hydrogen bond stabilizes the molecular conformation [graph-set motif R 2 2 (6)]. In the crystal, further N-HÁ Á ÁCl hydrogen bonds connect individual molecules into zigzag chains parallel to [001]. The chains are linked by weak C-HÁ Á ÁO hydrogen-bonding interactions into a threedimensional network.

Chemical context
Thiourea and thiourea derivatives constitute an interesting class of ligands, bearing a soft sulfur and a hard nitrogen donor atom in the sense of the HSAB (hard and soft acids and bases) concept. Such ligands are of relevance in biological systems because they exhibit a moderate inhibitory potency on the diphenolase activity of tyrosinase (Liu et al., 2016), antimicrobial and cytotoxic activity (Bielenica et al., 2015) and are developed for anti-hepatitis C virus (HCV) activity (Khatri et al., 2015). Copper(I) complexes with thiourea derivatives have received significant attention for several decades due to their antibacterial activity (Chetana et al., 2016), cytotoxic activity (Rauf et al., 2009), catalytic and oxidation properties (Gunasekaran et al., 2017). In this context, we report here on synthesis and crystal structure of the title compound, [CuCl(C 7 H 7 N 3 O 2 S)(C 18 H 15 P) 2 ], (I). ISSN 2056-9890

Structural commentary
The asymmetric unit of (I) comprises of one Cu I atom, one chloride ligand, two triphenylphosphane (PPh 3 ) ligands, and one 1-(4-nitrophenyl)thiourea (NPTU) ligand. The distorted tetrahedral coordination of the Cu I atom results from binding to the chloride ligand, the P atoms of the two PPh 3 ligands and the terminal S atom of the 1-(4-nitrophenyl)thiourea ligand (Fig. 1). The distortion is evident from the angular range around the Cu I atom [99.870 (15)-129.119 (16) ] and the disparate bond lengths (Table 1). The Cu-S distance in (I) is somewhat smaller than the values of 2.4148 (16) and 2.3942 (15) Å reported in molecules A and B, respectively, of [CuI(PPh 3 ) 2 (ptu)] (ptu is phenyl thiourea) (Nimthong et al., 2008). The formation of an intramolecular N-HÁ Á ÁCl hydrogen bond involving the primary amine functionality (N2-H2B; Table 2) creates a six-membered ring system with graph set motif R 2 2 (6).

Figure 2
Part of the crystal structure of (I), showing intermolecular N-HÁ Á ÁCl hydrogen bonds as dashed lines, forming a zigzag chain parallel to [001].

Database survey
A search of the Cambridge Structural Database (Version 5.37, Feb 2016 with two updates; Groom et al., 2016) revealed no complexes with the 1-(4-nitrophenyl)thiourea ligand, and only the crystal structure of the ligand itself has been reported (LONSEN; Xian et al., 2008). A search for phenylthiourea ligands with substitutions on the phenyl ring yielded 34 hits. Of these, four hits were Cu I complexes, namely IYUXOP01 (Li et al., 2006), TULXIJ, TULXUV (Grifasi et al., 2015) and TULXUV (Nimthong et al., 2008).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.