cis-{1-Butyl-3-[2-(phenylsulfanyl)ethyl]-4-imidazolin-2-yl-κ2 C 2,S′}dichloridoplatinum(II)

The title compound, [PtCl2(C15H20N2S)], was synthesized from the reaction between N-heterocyclic carbene(NHC)-thioether ligand and potassium tetrachloroplatinate. In the crystal, the molecules are linked via C—H⋯Cl and C—H⋯π interactions, forming a layer parallel to the ab plane.


Structure description
Nitrogen heterocyclic carbene (NHC) exhibits attractive advantages such as simple operation and mild conditions in organic catalytic synthesis (Enders et al., 2007). In addition, as a neutral two-electron donor, NHC is currently regarded as the most effective ligand for the synthesis of new organometallic complexes owing to its unique features (Hahn & Jahnke, 2008;Nelson & Nolan, 2013). The first distinctive characteristic is the strong donor property of NHC ligands, which makes the interaction with metal center closer (Perrin et al., 2001;Chianese et al., 2003). The second one is that NHC can be flexibly modified by introducing functional groups onto the nitrogen atoms of the N-heterocycle ring. Over the past two decades, numerous attempts have been made to construct diverse donor-functionalized NHCs and their organometallic complexes, and N-, O-and P-functionalized NHCs have been developed and applied in organic synthesis, drug discovery and materials science (Kü hl, 2007). However, there are still rare investigations of NHC with S-donor complexes (Liu et al., 2017). As soft and electron-rich ligands, thioethers usually have versatile coordination chemistry, and can form strong M-S bonds with the metal center (Bierenstiel & Cross, 2011;Yuan & Huynh, 2012). The development of new organometallic complexes bearing NHC-thioether ligands (Rosen et al., 2013) is thus highly desirable. In recent years, NHC complexes with group 10 metals have received increasing attention because of their catalytic activities. In contrast to data reports complexes of lighter homologues, Pt II -NHC complexes have been less well studied. The novel title metal Pt II complex combined with an NHC-thioether ligand was designed and synthesized.
The asymmetric unit of the title complex is composed of one Pt II ion, one NHC-thioether ligand, and two chloride ions. As shown in Fig. 1, the Pt II ion is four-coordinated by one C atom and one S atom of the NHC-thioether ligand, and by two chloride ions in a nearly square-planar environment. The thioether side chain coordinates to the Pt II atom in a chelating fashion, forming a six-membered ring with a distorted boat conformation. The Pt-C and Pt-S bond lengths are 1.968 (12) and 2.266 (3) Å , respectively, while the C-Pt-S bond angle is 87.93 (11) . The two Pt-Cl bond lengths are different from each other [Pt1-Cl1 = 2.360 (3) Å and Pt1-Cl2 = 2.329 (3) Å ]. In the crystal, molecules are linked via C-HÁ Á ÁCl and C-HÁ Á Á interactions (Table 1), forming a layer parallel to the ab plane (Figs. 2 and 3). A weak intramolecular C-HÁ Á Á interaction is also observed. Table 1 Hydrogen-bond geometry (Å , ).

Figure 2
A packing diagram of the title compound, showing intra-and intermolecular C-HÁ Á Á interactions (dashed lines).

Figure 3
A view of the crystal packing of the title complex. Dashed lines denote the intermolecular C-HÁ Á ÁCl hydrogen bonds.

Figure 1
The structure of the title complex, with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Synthesis and crystallization
N-Heterocyclic carbene (NHC)-thioether ligand was synthesized by a slight modification of a reported procedure (Liu et al., 2017). Butyl-imidazole and 2-chloroethylbenzene sulfide (molar ratio 1: 1) were dissolved in acetonitrile at 393 K for 2 days to obtain a dark-brown liquid, and then the solvent was removed by evaporation. The residue was washed repeatedly with diethyl ether, and a brownish-yellow solid was obtained. The title complex was synthesized from the reaction of the NHC-thioether ligand with potassium tetrachloroplatinate. A reaction tube was charged with the NHC-thioether ligand (0.1710 g, 0.576 mM) and 6 ml of acetonitrile. The tube was evacuated and back-filled with nitrogen. Then a solution of potassium tetrachloroplatinate (0.200 g, 0.480 mM) in 2 ml of water was added in the dark. Keeping it in the dark, the reaction mixture was allowed to stir at 353 K for 24 h. The mixture was concentrated in vacuo and purified by silica gel column chromatography. Pale-yellow rectangular crystals were obtained from the solution at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The anisotropy of displacement ellipsoid of atom C9 was restrained with ISOR.

data-1
IUCrData (2020). 5, x201433 full crystallographic data IUCrData (2020). 5, x201433 [https://doi.org/10.1107/S2414314620014339] 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.