(η6-Benzene){2-[2-(tert-butylsulfanyl)phenyl]pyridine-κ2 N,S}chloridoruthenium(II) hexafluoridophosphate

In the title compound, [RuCl(C6H6)(C15H17NS)]PF6, the cation adopts a three-legged piano-stool structure around the Ru(II) atom with an η6-benzene ligand, a chloride ligand and a 2-[2-(tert-butylsulfanyl)phenyl]pyridine (btppy) ligand. The btppy ligand acts as a N,S-bidentate ligand, forming a six-membered ring, which has an envelope conformation. The S—Ru—N bite angle is 86.76 (9)°, and the dihedral angle between the pyridine and benzene rings in btppy is 39.8 (2)°. The unit cell contains two pairs of racemic diastereomers with (S Ru,S S) and (R Ru,R S) configurations, in which the tert-butyl group on the coordinated S atom is distant from the η6-benzene ligand.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2364). We previously reported the structurally characterized ruthenium(II) arene complex with 4-(2'-pyridyl)dibenzothiophene (PyDBT), [RuCl(PyDBT)(η 6 -C 6 H 6 )]CF 3 SO 3 (Shibue et al., 2008). In this complex, PyDBT acts as a N,S-bidentate ligand to form chiral centers at Ru and S atoms. The pyridine and dibenzothiophene planes in PyDBT are twisted with respect to each other, and the dibenzothiophene moiety is in close proximity to the η 6 -benzene ligand. To clarify the steric interactions around the coordinated S atom, we present here the crystal structure of the title ruthenium(II) arene complex of 2-(2'-(t-butylthio)phenyl)pyridine (btppy).
There are two pair of racemic diastereomers with (S Ru , S S ) and (R Ru , R S ) configurations in the unit cell. The t-butyl group on the coordinated S atom is placed far from the η 6 -benzene ligand. An average Ru-C distance of 2.180 (6) Å in (I) is comparable to that in (II) (2.192 (4), 2.180 (4) Å). The Cl-Ru-S angle (93.84 (4)°) in (I) is larger than that in (II) (82.84 (3)°, 84.87 (3)°), and no significant interaction was observed between the t-butyl group and the chloro ligand.
Molecular modeling analysis suggests that the other diastereomers with configurations of (S Ru , R S ) and (R Ru , S S ) cause a severe repulsive interaction between the t-butyl group and the benzene ligand. The 1 H NMR spectrum of (I) in CDCl 3 revealed the presence of a single diastereomer. This suggests that the (S Ru , S S ) and (R Ru , R S ) isomers observed in the crystal are retained in solution. Similar stereoselectivity was recently reported for the iridium(III) complex [(η 5 -C 5 Me 5 )Ir(η 2 -ppy- et al., 2010), in which the structure of the chelate ring is analogous to that for btppy in (I).
supplementary materials sup-2 Experimental The btppy ligand was prepared according to a literature procedure (Clavier et al., 2003). For the synthesis of the title compound (I), [RuCl 2 (C 6 H 6 )] 2 (51 mg, 0.10 mmol) was added to a deoxygenated solution of btppy (50 mg, 0.21 mmol) in methanol (10 ml). The reaction mixture was refluxed for 6 h under an argon atmosphere. After cooling to room temperature, KPF 6 (60 mg, 0.33 mmol) was added. The resulting orange solution was concentrated under reduced pressure. The residue was dissolved in chloroform (10 ml), and the insoluble white solid was removed by filtration. The filtrate was concentrated under reduced pressure, and the resulting brown residue was recrystallized by vapor diffusion of diethyl ether into a dichloromethane solution to afford yellow crystals (19 mg, 15%). Anal.

Refinement
All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were located on calculated positions with C-H(aromatic) = 0.95 Å and C-H(methyl) = 0.98 Å, and were refined using a riding model with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of (I) with numbering scheme. Displacement ellipsoids are drawn at the 40% probability level.

Special details
Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . Rfactor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).