From Stoichiometric to Catalytic Binuclear Elimination in Rh–W Hydroformylations. Identification of Two New Heterobimetallic Intermediates

Cyclopentene hydroformylation, both stoichiometric and catalytic, is performed starting with Rh-4(CO)(12) and CpW(CO)(3)H as precursors. Synergism is observed. Isotopic labeling experiments confirm 30% of the product formation occurs via a catalytic binuclear elimination reaction. Two new intermediates are spectroscopically identified using band target entropy minimization and DFT, namely, RhW(CO)(7)Cp and CpW(CO)(3)H-C5H9CORh (CO)(4). The latter intermediate appears to be hydrogen bonded via two simultaneous eta(5)-C5H4-H center dot center dot center dot O=C interactions, one with the CO group on the acyl moiety and the other with a CO on rhodium.