UV Photoelectron and Theoretical Studies of Organometal Carbonyl Clusters of Ruthenium and Osmium. μ-Hydrido-μ3-Allyl and μ-Hydrido-μ3-Allenyl Triangulo Cluster Compounds

The electronic structures of μ-hydrido-μ₃-allyl and μ-hydrido-μ₃-allenyl triangulo clusters of ruthenium and osmium are discussed on the basis of both He I and He II gas-phase UV-PE spectra and CNDO quantum-mechanical calculations. The theoretical results contribute to the discussion of the PE data and to a deeper understanding of the bonding scheme in these very complex organometallic clusters. The description of the allyl cluster interactions in terms of one πAnd two σ bonds seems to be adequate. On the other hand, the formal distinction into one σ and two πBonds of the allenyl ligand cluster interaction is quite an oversimplification of the actual bonding scheme. The differences in thermodynamical stability between the allenyl and allyl derivatives are in agreement with the CNDO-computed total energies.