Synthesis, characterization, and reactivity of W2Ru3 clusters that containoxo and carbido ligands, obtained by direct C-O bond activation

Treatment of CpWRu3(CO)(12)(mu -H) with CpW(CO)(3)H in refluxing heptane af forded the cluster compound Cp2W2Ru3(CO)(13) (1) Single-crystal X-ray analy sis indicates a trigonal-bipyramidal cluster arrangement with both W atoms located at the equatorial positions. Pyrolysis of 1 in refluxing toluene ga ve the oxo-carbido cluster CpW(O)CpWRu3(mu (5)-C)(CO)(11) (2a) in moderate yield, whereas the condensation of LWRu3(CO)(12)(eta -H) and L'W(CO)(3)H (L = L' = Cp*; L , L' = Cp, Cp* or Cp*, Cp) afforded the derivatives LW(O)L'W Ru3(mu (5)-C)(CO)(11) (2b, L = L' = Cp*; 2c, L = Cp; L' = Cp*) exclusively. A combination of spectroscopic and structural data suggests that the compl exes 2 adopt a wingtip-bridged butterfly structure and possess a terminal o xo and an interstitial carbide ligand. Thus, the transformation from 1 to 2 illustrates an example of metal-assisted cleavage of the carbonyl C-O bond . Mechanistic considerations based on the result of O-17 labeling studies a re discussed. Furthermore, extensive heating of 2b,c in toluene leads via e limination of two CO ligands to the formation of the new cluster complexes LL'W-2(mu -O)Ru-3(mu (5)-C)(CO)(9) (3b, L = L' = Cp*; 3c, L = Cp; L' = Cp*) , in which a distorted-square-pyramidal core structure has been confirmed b y single-crystal X-ray analysis. Treatment of 3 with CO gives regeneration of the complexes 2 in high yield.