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The Reagent [K(18-crown-6)][RuH(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))] as a Precursor to New Ruthenacarborane
Dianne D. Ellis1, Samantha M. Couchman, John C. Jeffery
1Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798-7348, and School of Chemistry, The University, Bristol BS8 1TS, U.K.
Abstract:
In ethanol the charge-compensated molecule exo-nido-ruthenacarborane [5,6,10-{RuCl(PPh(3))(2)}-5,6,10-&mgr;-(H)(3)-10-H-7,8-C(2)B(9)H(8)] reacts with KOH to afford the anionic closo-complex [RuH(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))](-) isolated as its K(+) (2a) or [K(18-crown-6)](+) (2b) salt. Treatment of 2a with CO gives [Ru(CO)(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))] (3a) in high yield; its structure was determined by X-ray crystallography. In contrast 2b reacts with CO to yield the salt [K(18-crown-6)][RuH(CO)(PPh(3))(eta(5)-7,8-C(2)B(9)H(11))] (2d). Reaction of 2b with [RuCl(2)(PPh(3))(3)] affords [Ru(2)(&mgr;-H)(H)(PPh(3))(4)(eta(5)-7,8-C(2)B(9)H(11))] (5), which with CO produces [Ru(2)(&mgr;-H)(&mgr;-sigma: eta(5)-7,8-C(2)B(9)H(10))(CO)(4)(PPh(3))(2)] (6), the structure of which was established by X-ray diffraction. The molecule has a metal-metal bond bridged on one side by a hydrido ligand and on the other by a nido-7,8-C(2)B(9)H(10) fragment. The latter is eta(5)-coordinated to a ruthenium atom ligated by a PPh(3) and a CO ligand and is also sigma-bonded to the second ruthenium which carries three CO molecules and a PPh(3) group. The sigma bond utilizes a boron lying in an alpha site with respect to the carbons in the ring coordinated to the Ru(CO)(PPh(3)) moiety. Reactions between 2b or 2d and [CuCl(PPh(3))(3)] and [AuCl(PPh(3))], respectively, afford the bimetal complexes [RuM(&mgr;-H)(L)(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))] [M = Cu, L = PPh(3) (7a), L = CO (7b); M = Au, L = PPh(3) (8a), L = CO (8b)]. X-ray diffraction studies are reported for 7a and 8a, revealing in the case of the former a structure in which an exopolyhedral B-Hright harpoon-up Cu bond supplements the Ru(&mgr;-H)Cu interaction.