In situ generation of the fulvalene ligand via C-H activation by gray antimony and its incorporation into the tetrahedral cluster [(μ,η5:η5-C10H8) (η5-C5H5)M3(CO)6(μ3-Sb)] (M = Mo or W)

The first tetrahedral clusters containing a single "naked" antimony atom have been prepared by the thermolysis of [CPM(CO)(3)](2) (M = Mo or W) in the presence of gray antimony at 180degreesC in toluene in a sealed Carius tube. X-ray structural characterization revealed that, in addition to the incorporation of Sb in the cluster, it has also affected coupling of two Cp rings to form [(mu,eta(5):eta(5)-C10H8) (eta(5)-C5H5)-M-3(CO)(6)(mu(3)-Sb)]. It is only the second example of in situ formation of the fulvalene ligand for group-6 metal. Simultaneous with the C-C coupling reaction, a mirror of Sb forms on the reaction tube; this indicates that SbH3 is formed in the hydrogen abstraction step, which then subsequently decomposes at the tube wall.