Hexakis(acetonitrile-κN)ruthenium(II) bis(hexabromocarbadodecaborate) acetonitrile solvate

The title compound, [Ru(NCCH3)6](CH6B11Br6)2·CH3CN, consists of the ’naked’ ruthenium(II) cation surrounded by six acetonitrile molecules, each coordinated via the nitrogen atoms in a linear or nearly-linear fashion in a typical octahedral over-all arrangement. The cation is balanced by the two hexa-bromocarborane cage anionic fragments [CB11H6Br6]. Weak C—H⋯Br and B—H⋯Br interactions link neighboring anions.

The title compound, [Ru(NCCH 3 ) 6 ](CH 6 B 11 Br 6 ) 2 ÁCH 3 CN, consists of the 'naked' ruthenium(II) cation surrounded by six acetonitrile molecules, each coordinated via the nitrogen atoms in a linear or nearly-linear fashion in a typical octahedral over-all arrangement. The cation is balanced by the two hexa-bromocarborane cage anionic fragments [CB 11 H 6 Br 6 ]. Weak C-HÁ Á ÁBr and B-HÁ Á ÁBr interactions link neighboring anions.
We thank the National Science Foundation for financial support. Support of this research via the PRF 44692.01-GB award by the American Chemical Society and the Cottrell College Award CC6755 from Research Corporation is gratefully acknowledged. We are grateful to Dr Ilia A. Guzei (University of Wisconsin, Madison) for his help in the preparation of this submission. labile neutral ligands or weakly coordinating anions, such as trifluoromethanesulfonate, these complexes exhibit pro-catalytic reactivity with unsaturated hydrocarbons and alcohols (Burns and Hubbard, 1994;Pearsal et al., 2007). The present study's goal is introduction of the non-coordinating carborane cage anions of the [CB 11 H 12 ] family in order to increase the reactivity of the ruthenium catalytic center (Stasko et al., 2002). The synthetic route to the desired complexes includes protonation of the dialkyl starting material with the solvated proton salt of the weakly-coordinating anion (similar to Brookhart, et al., 1992). This process eventually results in stripping all the ligands off the ruthenium center to give the title compound comprised of the 'naked' hexa-acetonitrile ruthenium cationic fragment balanced by two hexa-bromo-carborane anionic fragments. The catalytic activity of this complex is currently under investigation.

Experimental
The compound was obtained by a prolonged exposure of the Cp*Ru(NO)(CH 3 ) 2 complex to an excess of carborane-based protonating agent [(C 2 H 5 OC 2 H 5 ) 2 H] + [CB 11 H 6 Br 6 ]in acetonitrile.
All synthetic procedures were carried out in inert atmosphere and in anhydrous solvents. The protonating agent [(C 2 H 5 OC 2 H 5 ) 2 H] + [CB 11 H 6 Br 6 ]and starting ruthenium complex Cp*Ru(NO)(CH 3 ) 2 were synthesized according to the reported procedures (Stasko et al., 2002;Bergman & Chang,1987). 20 mg (0.065 mmol) of Cp*Ru(NO)(CH 3 ) 2 were dissolved in 10 ml of CH 3 CN and the solution was added to 200 mg of solid [(C 2 H 5 OC 2 H 5 ) 2 H] + [CB 11 H 6 Br 6 ] -(0.265 mmol). Vigorous evolution of a gas (methane) was observed. The color of the solution gradually changed from dark red to dark purple-red. Initial product of the reaction, [Cp*Ru(NO)(CH 3 )(NCCH 3 )] [CB 11 H 6 Br 6 ], formed via a mono-protonation process and loss of one methane molecule from the starting material, was observed spectroscopically (by 1H NMR) in the aliquot of the reaction mixture taken after 4 hrs. The red crystals of the [Ru(NCCH 3 ) 6 ]] [CB 11 H 6 Br 6 ] 2 were grown from the reaction mixture in acetonitrile at ambient temperature under nitrogen by slow evaporation over a period of 3 weeks.

Refinement
All H-atoms were placed in idealized locations and refined as riding with appropriate thermal displacement coefficients U iso (H) = 1.2 or 1.5 times U eq (bearing atom).

supplementary materials sup-2
All H-atoms were placed in idealized locations with C-H distances of 0.981 Å for methyl carbons, and B-H and other C-H distances of 1.212 Å and refined as riding with thermal displacement coefficients U iso (H) set to 1.5 times U eq (bearing C atom) for the methyl atoms and 1.2 times U eq (bearing atom) otherwise. Fig. 1. Molecular structure of (I)with atom numbering scheme. The thermal ellipsoids are shown at 50% probability level.