Synthesis, Structures, Solution Behavior, and Reactions of Thiolato-Bridged Diruthenium Carbonyl Phosphine Complexes

Dinuclear thiolato-bridged complexes [Ru2(CO)4(μ-SR)2(PR‘3)2] (R‘ = Ph, Me) have been readily prepared from the reaction of [Ru2(CO)4(MeCN)4(PR‘3)2][BF4]2 (R‘ = Ph (1), Me (2)) with RSH (R = t Bu, i Pr, Ph) and Et3N at ambient temperature. Although only the syn form of [Ru2(CO)4(μ-S t Bu)2(PPh3)2] (3) and only the anti form of [Ru2(CO)4(μ-SPh)2(PMe3)2] (6) were found, an equilibrium mixture of both the syn (isomer A) and anti (isomer B) forms was present in solution for [Ru2(CO)4(μ-S i Pr)2(PPh3)2] (4) and [Ru2(CO)4(μ-SPh)2(PPh3)2] (5). The spectral data support that the syn form (4A) is the major isomer of 4, while the anti form (5B) is the major isomer of 5. The two thiolato bridges are located cis to the two phosphine ligands in solid-state structures 3, 4A, and 5B, but they are located cis to only one of the two ligands whereas they are trans to the other in structure 6. Iodination of 3−6 gave one identical product [Ru2(CO)4(μ-SR)2I2(PR‘3)2] (R‘ = Ph, R = t Bu (7), i Pr (8), Ph (9); R‘ = Me, R = Ph (10)). Both spectral and structural evidence shows that 7−10 exist in the syn form with no Ru−Ru bonding interaction. The relative orientation of the two thiolato bridges with respect to the two phosphine ligands present in 6 remains in structure 10, in spite of the change from anti to syn. The reactions of the diiodide complexes [Ru2(CO)4(μ-SR)2I2(PR‘3)2] with R‘‘S anions give either [Ru2(CO)4(μ-SR)2(PR‘3)2] and R‘‘SSR‘‘ or [Ru2(CO)4(μ-SR)2(SR‘‘)2(PR‘3)2].