Synthesis and structural characterization of mesitylphosphinidene-capped ruthenium and osmium clusters

Thermal reaction of [Ru3(CO)12] with PH2Mes (Mes = mesityl) in refluxing toluene afforded mesitylphosphinidene-capped ruthenium carbonyl clusters, [Ru3(CO)9(μ-H)2(μ3-PMes)] (1), [Ru3(CO)8(PH2Mes)(μ-H)2(μ3-PMes)] (2), [Ru3(CO)9(μ3-PMes)2] (3), [Ru4(CO)10(μ-CO)(μ4-PMes)2] (4), and [Ru5(CO)10H2(μ4-PMes)(μ3-PMes)2] (5). All products were fully characterized and structurally confirmed by X-ray crystal structure analysis. Complexes 2–4 were also obtained in high yields by stepwise reaction starting from 1. Fluxional behavior of carbonyl groups was observed in case of 4. Complex 5 reveals a new type of skeletal structure, bicapped-octahedron having μ3- and μ4-phosphinidene ligands at the capping positions. Similar reaction of [Os3(CO)12] with PH2Mes yielded a phosphido-bridged osmium cluster [Os3(CO)10(μ-H)(μ-PHMes)] (6) and a phosphinidene-capped cluster [Os3(CO)9(μ-H)2(μ3-PMes)] (7).