Carborane Complexes of Ruthenium: Synthesis and Structural Studies of Di- and Triruthenium Carbonyl Species

The compounds [Ru3(CO)12] and nido-7,8-Me2-7,8-C2B9H11 react in CH2Cl2 to yield a mixture of [Ru(CO)3(η5-7,8-Me2-7,8-C2B9H9)] (1b) and [Ru3(CO)8(η5-7,8-Me2-7,8-C2B9H9)] (2) in a ratio of ca. 1:2. The tri- and dinuclear ruthenium complexes [Ru3(μ-H)(μ-σ:η5-7,8-Me2-7,8-C2B9H8)(CO)7(PR3)] (PR3 = PPh3 (3), PCy3 (6)), [Ru3(μ-H)(μ-σ:η5-7,8-Me2-7,8-C2B9H8)(CO)6(PR3)2] (PR3 = PPh3 (4), PMe2Ph (5)), [Ru2(CO)4(PMe3)2(η5-7,8-Me2-7,8-C2B9H9)] (7), and [Ru3(μ-dppm)(CO)6(η5-7,8-Me2-7,8-C2B9H9)] (8) have been prepared by treating 2 with tertiary phosphines. A single-crystal X-ray diffraction study on 5 revealed the structure as one in which a triangular array of ruthenium atoms is bridged by a nido-7,8-Me2-7,8-C2B9H8 group. The latter is pentahapto coordinated to one Ru atom, which carries two CO ligands, and is linked to the other metal atoms by a Ru−B and a B−H⇀Ru bond, respectively. These two ruthenium atoms are each coordinated by two CO groups and one PMe2Ph group. Treatment of 2 with Me2NCH2NMe2 in CH2Cl2 affords ...