Heterobinuclear Vinyl, Allyl, and Related Complexes of Rhodium/Osmium from Terminal Alkynes and Allenes, Vinyl to Carbene Transformations, and the Structures of [RhOs(C(CH3)CH2)(CO)3(Ph2PCH2PPh2)2] and [RhOs(C(CH3)C(CH3)2)(CH3)(CO)3(Ph2PCH2PPh2)2][CF3SO3]

This paper reports the synthesis and characterization of a series of vinyl, vinyl−hydride, vinyl−alkyl, and related heterobimetallic complexes of Rh and Os. Reductive elimination reactions of the vinyl−hydride products and the transformations of vinyl groups to carbenes are also reported. Reaction of [RhOs(H)(CO) 3 (dppm) 2 ] ( 1, dppm = Ph 2 PCH 2 PPh 2 ) with propyne yields [RhOs(C(CH 3 ) CH 2 )(CO) 3 (dppm) 2 ] ( 3 ), and reaction with (CH 3 ) 2 C C CH 2 yields [RhOs(C(CH 3 ) C(CH 3 ) 2 )(CO) 3 (dppm) 2 ] ( 5 ). Reaction of 1 with allene yields 3 as the major product, together with small amounts of [RhOs(η 3 -C 3 H 5 )(CO) 3 (dppm) 2 ] ( 4 ). Compound 4 can be independently synthesized via reaction of (CH 2 CHCH 2 ) 2 Mg with [RhOs(CO) 4 (dppm) 2 ][BF 4 ] ( 2 ). Compound 3 reacts with CO to form the isopropenoyl complex [RhOs(C(O)C(CH 3 ) CH 2 )(CO) 3 (dppm) 2 ] ( 6 ). Both vinyl complexes 3 and 5 react with CH 3 SO 3 CF 3 to form [RhOs(C(CH 3 ) CR 2 )(CH 3 )(CO) 3 (dppm) 2 ][CF 3 SO 3 ] ( 7a, b R = H; 8a, b R = CH 3 ) and with HBF 4 ·Me 2 O to form [RhOs(C(CH 3 ) CR 2 )(H)(CO) 3 (dppm) 2 ][BF 4 ] ( 9a, b R = H; 10a, b R = CH 3 ). The isopropenoyl complex 6 reacts with HBF 4 ·Me 2 O to form [RhOs(C(O)C(CH 3 ) CH 2 )(μ-H)(CO) 3 (dppm) 2 ] [BF 4 ] ( 11 ). The vinyl−hydride compounds 9 and 10 rearrange under a CO atmosphere to form hydride-bridged isomers [RhOs(C(CH 3 ) CR 2 )(μ-H)(CO) 3 (dppm) 2 ][BF 4 ] ( 12a, b R = H; 13a, b R = CH 3 ), which subsequently reductively eliminate the alkene. Protonation of [RhOs(C(CH 3 ) CH 2 )(CH 3 )(CO) 3 (dppm) 2 ][CF 3 SO 3 ] ( 7 ) or [RhOs(C(CH 3 ) CH 2 )(H)(CO) 3 (dppm) 2 ][BF 4 ] ( 9 ) at low temperature results in formation of the carbene complexes [RhOs( C(CH 3 ) 2 )(R)(CO) 3 (dppm) 2 ][X][Y] ( 14 R = H, X = Y = BF 4; 15 R = CH 3, X = BF 4, Y = CF 3 SO 3 ) in which the carbene is terminally bound to Rh. Protonation of [RhOs(C(O)C(CH 3 ) CH 2 )(μ-H)(CO) 3 (dppm) 2 ][BF 4 ] ( 11 ) yields the carbene complex [RhOs( C(OH)C(CH 3 ) CH 2 )(μ-H)(CO) 3 (dppm) 2 ][BF 4 ] 2 ( 16 ). The structures of 3 and 8 have been established by X-ray crystallography. In compound 3, the isopropenyl group is terminally bound to Rh and three carbonyls are bound to Os, with one of them forming a semibridging interaction with Rh. The trimethylvinyl group in compound 8 is also bound terminally to Rh, while three carbonyls and the methyl group are on Os. Two of the carbonyls form semibridging interactions with Rh.