Electronic g Tensors in UV Complexes-A Computational Study.

Abstract

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 quantum chemical techniques have been used to evaluate the g tensor for UV complexes, for which experimental data are available for comparison. The g tensors were calculated using relatively simple, state-averaged complete active space self-consistent field (SA-CASSCF) calculations. This approach is shown to be capable of providing useful accuracy. Aspects of the computations that should be refined to provide a more quantitative approach are discussed. 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.