Electronic structure of 20-electron bis-(cyclopentadienyl)-metal oxo compounds of Group 6: investigation by photoelectron spectroscopy

Abstract

The He I and He II Photoelectron spectra have been recorded for [Mo(η-C₅H₄Me)₂O], [W(η-C₅H₄Me)₂O] and [W(η-C₅Me₅)₂O]. All show two low-ionization-energy bands, the lowest being assigned to the two metal d electrons and the second to an orbital based primarily on the cyclopentadienyl rings and an oxygen 2p orbital. Other cyclopentadienyl ionization bands and metal–oxygen bonding ionizations are also identified. The spectra confirm the SCF-Xα-SW bonding model presented previlously. Extended-Hückel calculations, which are in agreement with the SCF-Xα-SW calculations, have been used to model the orbital interactions. The metal–oxygen bonding and the nucleophilic character of the molecules is discussed in the light of the spectroscopic and theoretical results.