Electronic g Tensors in U(V) Complexes - A Computational Study

The theory and computation of EPR parameters from first principles has seen a great deal of development over the past two decades. In particular, various techniques for the computation of the electronic g tensor have been implemented in many quantum chemistry packages. These methods have been successfully applied to paramagnetic organic species and transition metal systems. The situation is less well-understood and established in the case of actinide containing molecules and there is a dearth of experimental data available for validation of computations. In this study we have used quantum chemical techniques to evaluate the g tensor for U(V) complexes, for which experimental data are available for comparison. The g tensors were calculated using, relatively simple, state averaged CASSCF calculations. We show that this approach is capable of providing useful accuracy. We discuss aspects of the computations that should be refined to provide a more quantitative approach. The key features of the underlying electronic structure that influence the computed g values are delineated, providing a simple physical picture of these subtle molecular properties.