(η6-Benzene)(2,2′-bipyridine-κ2 N,N′)chloridoruthenium(II) chloride methanol sesquisolvate

In the title compound, [RuCl(C6H6)(C10H8N2)]Cl·1.5CH4O, the RuII atom is in a distorted octahedral environment coordinated by an η6-benzene ring, a chelating 2,2′-bipyridine ligand and a chloride ion. The asymmetric unit is completed by a chloride anion and two methanol molecules, one of which is disordered about a centre of inversion with an occupancy of 0.5. It is an example of a ruthenium complex with a less sterically congested environment than in similar derivatives. In the crystal structure, O—H⋯Cl hydrogen bonds, together with π–π stacking interactions [centroid–centroid distances of 3.472Å(2) Å], stabilize the structure.

In the title compound, [RuCl(C 6 H 6 )(C 10 H 8 N 2 )]ClÁ1.5CH 4 O, the Ru II atom is in a distorted octahedral environment coordinated by an 6 -benzene ring, a chelating 2,2 0 -bipyridine ligand and a chloride ion. The asymmetric unit is completed by a chloride anion and two methanol molecules, one of which is disordered about a centre of inversion with an occupancy of 0.5. It is an example of a ruthenium complex with a less sterically congested environment than in similar derivatives. In the crystal structure, O-HÁ Á ÁCl hydrogen bonds, together withstacking interactions [centroid-centroid distances of 3.472Å (2) Å ], stabilize the structure.

Comment
The desire for a ruthenium complex which could be used to synthesize facially coordinated complexes led to the preparation of the starting material (1) (Freedman et al. 2001). It is convenient to use, in that the benzene ring can be readily removed in a photolytic reaction leaving ruthenium with three, vacant, facially arranged coordination sites. The Ru II atom is in a distorted octahedral environment, Table 1, coordinating to an η 6 -benzene ring, a chelating 2,2'-bipyridine ligand and a chloride anion.
Compared to other similar complexes from the literature, the cation is less bulky both around the benzene ring (Himeda et al., 2007) and in the bipyridine unit (Lalrempuia & Kollipara, 2003). This manifests itself in two angles. The angles between the mean plane of the bipyridine ligand and the mean plane of the benzene ring (60.47 (18)° in 1) become smaller as the ligands become larger due to additional substitution by methyl groups. This forces the two ligands become more parallel to each other. This effect is seen when either the bipyridine (32.24 ° Lalrempuia & Kollipara, 2003) or the benzene ring (36.04°H imeda et al. 2007) is larger due to additional substitution. With the smaller unsubstituted ligands of (1) the ruthenium atom is also more able to sit in the same plane as the bipyridine ligand, lying only 0.075 (1) Å above the plane in the direction of the choride ligand. The methanol solvate molecules form O-H···Cl hydrogen bonds to the chloride anion, Table 2, with D-H A distances of 3.013 (4) Å (O51-Cl2) and 2.986 (6) Å (O61-Cl2). The structure is further stabilized by offset π-π stacking interactions between adjacent N1, C7···C11 rings of the bipyridine ligands, with centroid to centroid distances of 3.472 (2) Å, related by the symmetry operation 1 -x, 1 -y, 1 -z, Fig. 2.

Experimental
The complex was prepared according to literature procedures (Freedman et al. 2001). X-ray quality crystals were grown by slow evaporation of a solution in methanol.

Refinement
The C and O atoms of both methanol solvate molecules were refined isotropically. One of these molecules (C60, O60) is disordered about an inversion centre and was refined with the occupancy of all atoms fixed at 0.5. A l l H-atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.93 Å, U iso =1.2U eq (C) for aromatic, 0.96 Å, U iso = 1.5U eq (C) for CH 3 atoms and 0.82 Å, U iso = 1.5U eq (O) for the OH groups. Fig. 1. The molecular structure of (1), showing displacement ellipsoids at the 50% probability level.