Abstract

The lanthanocences and actinocenes - M(COT)2(COT =8-C8H8) - are the prototypical f-element organometallic species, in part because their D8h structure is not found elsewhere in the periodic table. As part of a wider study into M(COT)2(M = f element) ,we recently revisited Ce(COT)2 using CASSCF and CASPT2 computational techniques. We obtained excellent agreement with experiment for the Ce–COT distance, the electronic excitation energies and the f electron occupancy. We also established that characterization of the ground state using the approach of other researcher (i.e. in terms of CASSCF configurations) is ambiguous, and hence that a more robust description of the electronic structure is required. In this contribution I shall present such a description, applicable to Ce(COT)2 and its actinide analogues.