Clusters Containing a Quadruply Bridging CO Ligand. Syntheses, Crystal Structures, and Solution Dynamics of CpWRu4(CO)14H and Cp*MRu4(CO)14H (M = Mo, W)

The pentametal carbonyl cluster compounds CpWRu4(CO)14(μ3-H) (4), Cp*MoRu4(CO)14-(μ3-H) (5), and Cp*WRu4(CO)14(μ3-H) (6) were obtained by condensation of Ru3(CO)12with the corresponding anionic reagents [CpW(CO)3][PPN] and [Cp*M(CO)3][PPN] (M = Mo,' W) in the ratio 3:2 in refluxing THF solution, followed by treatment with excess CF3CO2H in CH2Cl2at room temperature. The Cp derivative 4 possesses a trigonal-bipyramidal Ru4W core in which the W atom is located at an equatorial position and the hydride lies on a Wru 2triangular face. In contrast, the Cp* derivatives 5 and 6 adopt an edge-bridged tetrahedral geometry with a tentacle Cp*M fragment bridging a Ru-Ru edge, on which the novel μ4-η2-CO ligand is associated with the local butterfly Ru3M array (M = Mo, W). The solution dynamics of these three cluster compounds are discussed.