Photoelectron spectroscopy of f-element organometallic complexes. 4. Comparative studies of bis(pentamethylcyclopentadienyl) dichloride and dimethyl complexes of uranium(IV), thorium(IV), and zirconium(IV)

This paper presents the first comparative study of the photoelectron spectra of a series of transition-metal and actinide organometallic compounds with exactly the same ligand array, i.e., M[η⁵-(CH₃)₅C₅]₂X ₂ where M = Zr, Th, and U and X = CH₃ and Cl. Studies were performed with both He I and He II photon energies. It is found that the bonding in these complexes is rather similar, and differences within the series are smaller than would be encountered in changing to M = Nb or Mo. The major differences between Zr and the actinides appear to arise from metal-ligand bonding involving metal 5f orbitals. A distinctive 5f² ionization signal is observed in the spectra of both uranium complexes.