Undecacarbonyl[(4-methylsulfanylphenyl)diphenylphosphane]triruthenium(0): crystal structure and Hirshfeld surface analysis

In Ru3(CO)11PPh2(C6H4SMe-4), the phosphane ligand occupies an equatorial position. In the crystal, phenyl-C—H⋯O(carbonyl) and carbonyl-O⋯O(carbonyl) interactions general a [111] supramolecular chain.


Chemical context
Tertiary phosphanes (PR 3 ) have played a major role in the formation and subsequent chemistry of metal carbonyl clusters, often relating to the promising catalytic activity of the products (Bruce et al., 2005;Shawkataly et al., 2013;Park et al., 2016). In general, the thermal reaction of Ru 3 (CO) 12 with PR 3 leads to Ru 3 (CO) 12 -n (PR 3 ) n , n = 1-4, cluster compounds (Bruce et al., 1988(Bruce et al., , 1989. The steric and electronic effects of PR 3 often results in the lengthening of Ru-Ru bonds in the Ru 3 triangle as compared with the parent compound, Ru 3 (CO) 12 , thereby making the cluser more reactive (Bruce et al., 1989). The PPh 2 C 6 H 4 SMe ligand is of interest because it contains two different potential donor groups, i.e. P and S, which can result in variable substitution patterns. For example, in the Cu 22 Se 6 (SePh) 10 [PPh 2 (C 6 H 4 SMe)] 8 cluster, only the P atom of the PPh 2 C 6 H 4 SMe ligand is coordinated to the metal centre while the thiomethyl group remains uncoordinated (Fuhr et al., 2002). However, the thiomethyl group can further react with other metal atoms to provide opportunities in surface chemistry (Fuhr et al., 2002). The known crystal structures of triruthenium clusters with the PPh 2 (C 6 H 4 SMe) ligand are surprisingly few in number (Shawkataly et al., 2011a,b). Herein, the crystal and molecular structures of the title compound, Ru 3 (CO) 11 PPh 2 (C 6 H 4 SMe-4) (I), are ISSN 2056-9890 described as well as an analysis of the calculated Hirshfeld surface.

Structural commentary
The molecular structure of Ru 3 (CO) 11 PPh 2 (C 6 H 4 SMe-4), (I), is shown in Fig. 1. The molecule comprises an Ru 3 triangle with one Ru centre being bound, equatorially, by the phosphane ligand. The Ru-Ru bond lengths in the Ru 3 triangle are not equivalent with the Ru1-Ru2 bond of 2.8933 (2) Å being longer than the Ru1-Ru3 and Ru2-Ru3 bonds of 2.8575 (2) and 2.8594 (3) Å , respectively. This disparity probably reflects the steric hindrance exerted by the phosphane ligand which occupies the region in the vicinity of the Ru1-Ru2 bond. Some general trends in the geometric parameters involving the carbonyl ligands may be discerned, the relatively high errors in some of the parameters notwithstanding. Thus, the Ru-C bond distances involving carbonyl groups lying in the plane of the Ru 3 ring are generally shorter than those occupying positions perpendicular to the plane, with the respective ranges in Ru-C bond lengths being 1.897 (3)-1.930 (3) Å and 1.937 (2)-1.953 (3) Å . While the Ru-C O angles are all close to linear, two distinctive ranges in angles are evident. The Ru-C O angles involving carbonyl groups lying in the plane of the Ru 3 ring lie in the range 177.3 (2)-178.7 (2) while the range for the perpendicularly orientated carbonyl groups is 172.1 (2)-174.6 (2) . The trend for longer Ru-C distances and greater deviations from linearity of the Ru-C O angles for the axial carbonyl ligands, which occupy positions trans to other carbonyl ligands, is consistent with some semi-bridging character for these carbonyl ligands. Thus, the closest intramolecular RuÁ Á ÁC(carbonyl) contact of 3.233 (3)     The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 70% probability level.

Supramolecular features
The molecular packing of (I) features phenyl-C-HÁ Á ÁO(carbonyl) interactions occurring about a centre of inversion and leading to centrosymmetric dimers, Table 1. Connections between the dimers leading to a supramolecular chain along [111] are of the type carbonyl-OÁ Á ÁO(carbonyl), Fig. 2a. The O3Á Á ÁO3 i separation is 2.817 (2) Å , a distance less than the sum of the van der Waals radii of oxygen, i.e. 3.04 Å (Bondi, 1964); symmetry operation (i): 1 À x, 1 À y, 1 À z. Such intermolecular OÁ Á ÁO interactions are examples of homoatomic chalcogen bonding which are rarest for the smaller oxygen atoms (Gleiter et al., 2018). The chains pack without directional interactions between them according to the criteria assumed in PLATON (Spek, 2009). A view of the unit-cell contents is shown in Fig. 2b.

Analysis of the Hirshfeld surface
The Hirshfeld surface calculations of (I) were performed in accordance with a recent publication on a related ruthenium cluster compound (Shawkataly et al., 2017). Two views of the Hirshfeld surface mapped over d norm are shown in Fig. 3. A spot near the O8 atom in Fig. 3a, results from the C21-HÁ Á ÁO8 interaction (Table 1). The presence of a diminutive red spot near the carbonyl-O3 atom in Fig. 3b reflects the significance of the short O3Á Á ÁO3 contact mentioned in Supramolecular features. The intense red spots near the methylsulfanylbenzene-C16 and phenyl-H28 atoms indicate the significance of this short interatomic CÁ Á ÁH/HÁ Á ÁC contact (Table 2; calculated in CrystalExplorer3.1 (Wolff et al., 2012). In addition, interactions involving several carbonyl groups results in short OÁ Á ÁO and CÁ Á ÁO/OÁ Á ÁC contacts (Table 2) and are characterized as faint red spots in Fig. 3. The Hirshfeld surfaces mapped over the electrostatic potential illustrated in Fig. 4 also reflect the involvement of different atoms in the intermolecular interactions through the appearance of blue and red regions around the participating atoms, and correspond to positive and negative electrostatic potential, respectively. As highlighted in Fig. 4a, an intramolecular carbonyl-C4 O4Á Á ÁCg(C19-C24) contact is evident. CarbonylÁ Á Á(arene) interactions are known to be important in the structural chemistry of metal carbonyls (Zukerman-Schpector et al., 2011). Here, the O4Á Á ÁCg(C19-C24) separation is 3.850 (3) Å and the angle subtended at the O4 atom is 90.1 (2) , indicating a side-on (parallel) approach between the residues. The environment about a reference molecule, showing short interatomic OÁ Á ÁO and CÁ Á ÁH/HÁ Á ÁC contacts significant in the molecule packing of (I), is illustrated in Fig. 5.
The overall two-dimensional fingerprint plot for (I) and those delineated into HÁ Á ÁH, OÁ Á ÁH/HÁ Á ÁO, OÁ Á ÁO, CÁ Á ÁH/ HÁ Á ÁC and CÁ Á ÁO/OÁ Á ÁC contacts (McKinnon et al., 2007) are illustrated in Fig. 6; the percentage contributions from the different interatomic contacts to the Hirshfeld surfaces are summarized in Table 3. In the fingerprint plot delineated into HÁ Á ÁH contacts, the relatively small, i.e. 15.6%, contribution from these contacts to the Hirshfeld surfaces is due to the presence of the carbonyl groups on the Ru-cluster which leads to an increase in the contribution of OÁ Á ÁH/HÁ Á ÁO contacts to the Hirshfeld surface, i.e. 37.4%. The single tip at d e + d i $2.4 Å in the HÁ Á ÁH delineated fingerprint plot, which has a broad appearance, arises from a van der Waals contact between the methyl-H18B and phenyl-H20 atoms ( Two views of the Hirshfeld surface of (I) mapped over d norm in the range À0.106 to +1.524 au. Table 2 Summary of short interatomic contacts (Å ) in (I).

Figure 4
Two views of the Hirshfeld surface of (I) mapped over the electrostatic potential in the range AE0.046 au. The red and blue regions represent negative and positive electrostatic potentials, respectively.
result of the interatomic C-HÁ Á ÁO interaction discussed above (Table 1) and a short interatomic OÁ Á ÁH/HÁ Á ÁO contact (Table 2), respectively. The influence of the significant interatomic O3Á Á ÁO3 contact (Fig. 5) and other such short interatomic contacts (  Table 3 have negligible effect on the packing.

Synthesis and crystallization
All reactions were carried out under an inert atmosphere of oxygen-free nitrogen (OFN) using standard Schlenk techni-

Figure 5
A view of the Hirshfeld surface of (I) mapped over d norm in the range À0.090 to +1.204 au highlighting OÁ Á ÁO and CÁ Á ÁH/HÁ Á ÁC contacts by sky-blue and red dashed lines, respectively. ques. Ru 3 (CO) 12 was purchased from Aldrich and PPh 2 C 6 H 4 SMe was synthesized as reported previously (Fuhr et al., 2002). Ru 3 (CO) 11 P(C 6 H 4 SMe-4)Ph 2 (I) was synthesized by dissolving Ru 3 (CO) 12 (100 mg, 0.0015 mmol) and PPh 2 (C 6 H 4 SMe) (48 mg, 0.0015 mmol) in tetrahydrofuran (25 ml). The reaction mixture was treated dropwise with sodium diphenylketyl solution until the colour of the mixture turned from orange to dark red and then stirred for 30 min.
The solvent was evaporated under vacuum and the residue was chromatographed by preparative TLC. Elution with 7:3 n-hexane/dichloromethane mixture gave four bands and the major orange fraction was characterized as (I) (117 mg, 79.6%). Orange crystals were crystallized from solvent diffusion of dichloromethane into a methanol solution of (I

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. The carbon-bound H atoms were placed in calculated positions (C-H = 0.95-0.98 Å ) and were included in the refinement in the riding-model approximation, with U iso (H) set to 1.2-1.5U eq (C). Owing to poor agreement, four reflections, i.e. (1 7 14), (10 2 6), (3 12 12) and (6 16 10), were omitted from the final cycles of refinement. The maximum and minimum residual electron density peaks of 1.97 and 0.98 e Å À3 , respectively, were located 0.69 and 0.61 Å from the atoms Ru1 and Ru3, respectively.

Undecacarbonyl[(4-methylsulfanylphenyl)diphenylphosphane]triruthenium(0)
Crystal data 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.