CH and PC bond activations of PMe2Ph ligands by an octahedral Ru6 cluster

The compound Ru6(CO)15(PMe2Ph)2(μ6-C) (1) was obtained from the reaction of Ru6(CO)17(μ6-C) with PMe2Ph. Compound 1 exists in solution as a mixture of two slowly interconverting isomers. It is decarbonylated by treatment with Me3NO·2H2O to yield two new products Ru6(CO)13(μ-PMe2)(μ3-η3-Me2PC6H4)(μ6-C) (2) and Ru6(CO)14(PMe2Ph)(μ-η2-MePhPCH2)(μ6-C)(μ-H) (3). Compound 2 is also obtained from 1 by thermal decarbonylation at 127 °C together with two additional compounds: Ru6(CO)14(μ-PMe2)(μ-η2-MePhPCH2)(μ6-C) (4) and Ru6(CO)12(μ-PMe2)2(μ3-η2-C6H4)(μ6-C) (5). Compound 2 reacts reversibly with CO to form the CO adduct Ru6(CO)14(μ-PMe2)(μ-η2-Me2PC6H4)(μ6-C) (6). The structures of compounds 1–6 were established crystallographically. All contain octahedral Ru6 clusters with a carbido ligand in the center. Except for 1, all contain phosphine ligands in various stages of degradation. Compound 2 contains one bridging PMe2 ligand formed by loss of a phenyl ring from a PMe2Ph ligand and a bridging η3-Me2PC6H4 ligand formed by ortho-metallation of the phenyl ring of the second PMe2Ph ligand. Compound 3 contains a bridging η2-MePhPCH2 ligand formed by metallation of one of the methyl groups of a PMe2Ph ligand. Compound 4 contains a bridging PMe2 and a bridging η2-MePhPCH2 ligand. Compound 5 contains two bridging PMe2 ligands and a bridging (μ3-η2-C6H4) benzyne ligand fromed by cleavage of a phenyl ring from one of the PMe2Ph ligands. Compound 6 contains one bridging PMe2 ligand and a bridging η2-Me2PC6H4 ligand formed by ortho-metallation of the phenyl ring of one of the PMe2Ph ligands.