Crystal structure of (μ-4-hydroxybenzenethiolato-κ2 S:S)bis(μ-phenylmethanethiolato-κ2 S:S)bis[(η6-1-isopropyl-4-methylbenzene)ruthenium(II)] tetrafluoridoborate

The two RuII cations, each with the characteristic piano-stool coordination geometry, are bridged by three thiolate ligands. The resulting dinuclear complex cation exhibits point group symmetry 1.

The crystal structure of the dinuclear arene ruthenium title complex, [Ru 2 (C 6 H 5 OS)(C 7 H 7 S) 2 (C 10 H 14 ) 2 ]BF 4 , shows the two Ru II atoms to be bridged by two benzylthiophenolate units and one 4-hydroxythiophenolate unit, with the remaining three coordination sites of each Ru II atom being occupied by p-cymene ligands, completing the typical piano-stool coordination geometry. The BF 4 À counter-anion is surrounded by four cationic dinuclear complexes, showing an O-HÁ Á ÁF hydrogen bond and several weak C-HÁ Á ÁF interactions. This is the first example of an X-ray analysis of a mixed dinuclear trithiolate arene ruthenium(II) complex.

Chemical context
In the search for novel metal-based anticancer agents, several series of dinuclear trithiolate arene ruthenium complexes have been synthesized by our group (Gras et al., 2010;Giannini et al., 2012Giannini et al., , 2013a. The biological studies in vitro showed the chloride salts of these complexes to have IC 50 values regularly in the nanomolar range, making them some of the most active ruthenium complexes found to date. The recent discovery of dithiolate complexes  allowed us to synthesize the so-called mixed trithiolate complexes of the type  i Pr) 2 Ru 2 (SCH 2 R 1 ) 2 (S-p-C 6 H 4 -R 2 ] + (R 1 = C 6 H 5 , CH 2 C 6 H 5 , p-C 6 H 4 t Bu; R 2 = H, OH, F, Br, i Pr, t Bu). All of the complexes were found to be highly cytotoxic against ovarian cancer cell lines A2780 and A2780cisR as chloride salts, none of them could however be crystallized and analyzed by X-ray crystallography (Giannini et al., 2013b). Herein we report the isolation and the crystal structure of the title compound,  i Pr) 2 Ru 2 (SCH 2 C 6 H 5 ) 2 (S-p-C 6 H 4 OH)]BF 4 , (I), the first reported structure of a mixed trithiolate complex. ISSN 2056-9890

Structural commentary
The structures of the molecular components of compound (I) are presented in Fig. 1. Both Ru II atoms adopt the typical piano-stool geometry with the p-cymene ligand being bound facially, formally occupying three coordination sites; the other three positions are occupied by two benzylthiophenolate units and one 4-hydroxythiophenolate unit. In agreement with the electron count, there is no metal-metal bond, the RuÁ Á ÁRu distance being 3.3632 (4) Å . The interatomic distances between Ru1 and S1, S2 and S3 are 2.3878 (9), 2.4023 (9) and 2.3813 (8) Å , respectively, and between Ru2 and S1, S2 and S3 2.3992 (9), 2.3991 (8) and 2.3882 (8) Å , respectively, showing that the central diruthenium trithiolate unit is not symmetric. The presence of the two bent benzylthiolate ligands forces the dinuclear arene ruthenium unit to adopt a distorted geometry -the angle between the two p-cymene planes (C1-C6 and C11-C16) is 6.2 (2) . The distances between the Ru II atoms and the centroids of the associated rings are 1.708 and 1.709 Å .

Supramolecular features
In the crystal packing of (I), the BF 4 À anion interacts with the -OH group of the 4-hydroxythiophenolate unit. In addition, weak C-HÁ Á ÁF interactions are observed (Table 1), thus creating around the BF 4 anion a densely packed arrangement (Fig. 2). No significant C-HÁ Á Á orstacking interactions are observed in the crystal structure.

Figure 2
Surroundings of the BF 4 À anion in the crystal packing of (I).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were included in calculated positions and treated as riding atoms, with C-H = 0.93 Å for C arom and 0.96 Å for CH 3 , and with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. ; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-32 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).  Kα graphite monochromated radiation. Image plate distance 100 mm, φ oscillation scans 0 -180°, step Δφ = 1.2°, 5 minutes per frame. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.