Crystal structure of bis[μ-(4-methoxyphenyl)methanethiolato-κ2 S:S]bis[chlorido(η6-1-isopropyl-4-methylbenzene)ruthenium(II)] chloroform disolvate

In the title complex, the two symmetry-related RuII atoms are bridged by two 4-methoxy-α-toluenethiolate [(4-methoxyphenyl)methanethiolate] units. One chloride ligand and the p-cymene ligand complete the typical piano-stool coordination environment of the RuII atom. In the crystal, the CH moiety of the chloroform molecule interacts with the chloride ligand of the dinuclear complex, while one Cl atom of the solvent interacts more weakly with the methyl group of the bridging 4-methoxy-α-toluenethiolate unit. This assembly leads to the formation of supramolecular chains extending parallel to [021].

The molecular structure of the title complex, [Ru 2 (C 8 H 9 OS) 2 Cl 2 (C 10 H 14 ) 2 ]Á-2CHCl 3 or (p-MeC 6 H 4 Pr i ) 2 Ru 2 (SCH 2 -p-C 6 H 5 -OCH 3 ) 2 Cl 2 Á2CHCl 3 , shows inversion symmetry. The two symmetry-related Ru II atoms are bridged by two 4-methoxy--toluenethiolato [(4-methoxyphenyl)methanethiolato] units. One chlorido ligand and the p-cymene ligand complete the typical piano-stool coordination environment of the Ru II atom. In the crystal, the CH moiety of the chloroform molecule interacts with the chlorido ligand of the dinuclear complex, while one Cl atom of the solvent interacts more weakly with the methyl group of the bridging 4-methoxy--toluenethiolato unit. This assembly leads to the formation of supramolecular chains extending parallel to [021].

Chemical context
Several series of dinuclear trithiolato arene ruthenium(II) complexes have been synthesized by our group in recent years (Gras et al., 2010;Giannini et al., 2011Giannini et al., , 2013a and investigated for their potential as anticancer agents (Giannini et al., 2012). The in vitro studies showed the IC 50 values of the chloride salts of these complexes to be regularly in the nanomolar range, being among the most active ruthenium complexes synthesized to date. The recent discovery of dithiolato complexes  opened new possibilities for the design of thiolato-bridged dinuclear arene ruthenium(II) complexes (Giannini et al., 2013b). Herein we report the structure of a neutral dithiolato complex, p-MeC 6 H 4 Pr i ) 2 Ru 2 (SCH 2 -p-C 6 H 5 -OCH 3 ) 2 Cl 2 that crystallized as a chloroform disolvate.

Supramolecular features
In the crystal packing of the title compound, the chlorido ligand of the complex interacts with the CH moiety of the chloroform molecule. Moreover, a more weak hydrogenbonding interaction is also observed between the methoxy group of the 4-methoxy--toluenethiolato and a chlorine atom of the solvent molecule (Table 1). These interactions give rise to the formation of supramolecular chains extending parallel to [021] (Fig. 2).

Synthesis and crystallization
The title complex was obtained from the reaction of 100 mg (0.163 mmol) of (p-MeC 6 H 4 Pr i ) 2 Ru 2 Cl 4 and 50.3 ml (0.343 mmol) of 4-methoxy--toluenethiol in ethanol. The solution was stirred at room temperature for 3 h, afterwards the solvent was reduced to 2 ml in vacuo and the product precipitated by adding hexane. The solid was filtered, washed with hexane and dried in vacuo. X-ray quality crystals were obtained by slow diffusion of diethyl ether into the solution of the title complex in chloroform.

Figure 2
The one dimensional supramolecular network in the crystal packing of (p-MeC 6 H 4 Pr i ) 2 Ru 2 (SCH 2 -p-C 6 H 5 -OCH 3 ) 2 Cl 2 Á2CHCl 3 . Only the stronger of the C-HÁ Á ÁCl interactions is shown (dotted lines

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All hydrogen atoms were included in calculated positions and treated as riding atoms, with C-H = 0.93 Å for C aromatic , 0.97 Å for -CH 2 -, 0.98 Å for -CH-, and 0.96 Å for -CH 3 , with U iso (H) = 1.2U eq (C) and 1.5U eq (C) for methyl H atoms.