Photochemistry of the Tetranuclear Clusters H2Ru4(CO)13, H2FeRu3(CO)13, and H2FeOs3(CO)13

Article abstract of DOI:10.1021/ja00414a023

Photolysis of H2FeRu3(CO)13, H2Ru4(CO)13, and H2FeOs3(CO)13 in the presence of PPh3 and H2 leads to formation of the corresponding H2M4(CO)12(PPh3) and H4M4(CO)12 clusters with moderate efficiency.The 366-nm quantum yields for PPh3 substitutions are 0.030, 0.016, and 0.057, respectively.Photolysis of these clusters in the presence of CO leads to cluster fragmentation but with low quantum efficiency (Φ <*> 10^-5).The quantum yield for PPh3 substitution in H2FeRu3(CO)13 is independent of PPh3 concentratiion but is decreased in the presence of added CO, implying competition of CO with PPh3 for a photogenerated intermediate.The mechanism most consisitent with all the experimental observations is one involving CO dissociation in the primary photochemical event, and not metal-metal bond homolysis.