ELECTRONIC STRUCTURE OF PROTACTINOCENE

$^{1}$A.H. H. Chang and R.M. Pitzer. J. Am Chem. Soc., 111 (1998) 2500.Author Institution: Department of Chemistry, The Ohio State UniversityThe electronic structure of protactinocene $(Pa(C_{8} H_{8})_{2})$ was studied using {ab initio} quantum chemical method including relativistic core potentials, gaussian double zeta basis sets, and spin orbit configuration interaction calculations. The lower states of protactinocene are $5f_{1}$ states. The $5f_{\pm 2}(C_{2u})$ are raised in energy compared to the other 5f $states^{1}$ because of the interaction of the $5f_{\pm2}$ orbitals with the highest occupied ligand $\pi$ MOS, while $5f_{\pm 3}(C_{3u})$ the states are lowered to a small extent by interaction with the unoccupied ligand $\pi^{*} e_{3u}$ MOs. The 6d states are split apart much more due to their considerably stronger $interactions^{1}$ with ligand $\pi$ orbitals, leaving only then $6d_{0} (a_{2u})$ state at low energy. The ground state is thus $E_{5/2u}$ and transitions from it to the other $5f^{1}$ states and the low-lying $6d^{1}$ state are not allowed. The lowest allowed state was computed at 3.67 eV. The calculated ground state magnetic moment is 1.96 Bohr magnetrons