Photoelectron spectroscopy of ƒ-element organometallic complexes: VII. Studies of di-cyclopentadienyluranium(IV) complexes containing tetrahydroborate, amido, pivalate and dithiocarbamate ligands

Abstract

A study of gas phase photoelectron spectra of a series of U(η 5-C 5H 5) 2X 2 (X = BH 4, NEt 2 O 2CC(CH 3) 3, S 2CNEt 2) complexes has revealed changes in the sequence of upper filled molecular orbitals along the series. In all cases the first ionization event corresponds to removal of uranium 5ƒ electrons. In the case of X = NEt 2, the next highest occupied ligand-based MO is an almost pure N2 p lone pair, but in the other complexes this MO is π-ring in nature. The observations are consistent with the higher reactivity of the amido complexes toward molecules containing polar double bonds or acidic hydrogens and with the greater labilities of the UCp bonds in the other complexes.