CARBORANE COMPLEXES OF RUTHENIUM - SYNTHESIS AND STRUCTURAL STUDIES OF DIRUTHENIUM AND TRIRUTHENIUM CARBONYL SPECIES

The compounds [Ru-3(CO)(12)] and nido-7,8-Me(2)-7,8-C2B9H11 react in C H2Cl2 to yield a mixture of [Ru(CO)(3)(eta(5)-7,8-Me(2)-7,8-C2B9H9)] ( 1b) and [Ru-3(CO)(8)(eta(5)-7,8-Me(2)-7,8-C2B9H9)] (2) in a ratio of c a. 1:2, The tri- and dinuclear ruthenium complexes sigma:eta(5)-7,8-Me (2)-7,8-C2B9H8)-(CO)(7)(PR(3))] (PR(3) = PPh(3) (3), PCy(3) (6)), sigm a:eta(5)-7,8-Me(2)-7,8-C2B9H8)-(CO)(7)(PR(3))] = PPh(3) (4), PMe(2)Ph (5)), 2)(CO)(4)(PMe(3))(2)(eta(5)-7,8-Me(2)-7,8-C2B9H9)] (7), and u-3( mu-dppm)-(CO)(6)(eta(5)-7,8-Me(2)-7,8-C2B9H9)] (8) have been prepared by treating 2 with tertiary phosphines. A single-crystal X-ray diffrac tion study on 5 revealed the structure as one in which a triangular ar ray of ruthenium atoms is bridged by a nido-7,8-Me(2)-7,8-C2B9H8 group . The latter is pentahapto coordinated to one Ru atom, which carries t wo 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 coordi nated by two CO groups and one PMe(2)Ph group, Treatment of 2 with Me( 2)NCH(2)NMe(2) in CH2Cl2 affords a mixture of the complexes ta(5)-7,8- Me(2)-10-CH(2)NMe(2)-7,8-C2B9H8)(CO)(5)] (9) and Ru-2(CO)(5)(NHMe(2))( eta(5)-7,8-Me(2)-7,8-C2B9H9)] (10) The structures of both diruthenium compounds were established by X-ray diffraction, In 9 the Ru-Ru bond i s bridged by the 7,8-Me(2)-10-CH(2)NMe(2)-7,8-C2B9H8 cage system, The open pentagonal <(CCBBB)over bar> face is coordinated to one Ru atom, which also carries two CO molecules, while the exopolyhedral CH(2)NMe( 2) group is coordinated to the other Ru atom which is also ligated by three CO molecules, In 10 a Ru(CO)(2)(eta(5)-7,8-Me(2)-7,8-C2B9H9) moi ety with a closo-3,1,2-RuC2B9 framework is linked by exopolyhedral Ru- Ru and B-H-->Ru bonds to a Ru(CO)(3)(NHMe(2)) group. The reaction betw een 2 and pyridine affords a mixture of [Ru-2(CO)(5)(NC5H5)(eta(5)-7,8 -Me(2)-7,8-C2B9H9)] (11) and (2)(CO)(4)(NC5H5)(2)(eta(5)-7,8-Me(2)-7,8 -C2B9H9)] (12). An X-ray diffraction study on 11 revealed a molecular structure similar to that of 10. The new compounds have been character ized by NMR spectroscopy in addition to the X-ray diffraction studies.