Monday, June 18, 2007
Golden Eagle Eyrie (Boise Centre on the Grove)

A Density Functional Study of Actinyl - Methoxide Complexes: the Structure and Bonding Properties

Da Gao and Michael E. McIlwain. Idaho National Laboratory, Idaho Falls, ID

The structure and reactivity of actinyl complexes have been an active topic of research in the chemical community because the participation of s, d and f orbital offers a broad array of possible structures and reaction pathways. Motivated by the desire to better understand and then manipulate actinides chemistry, the present work has systematically investigated the structure and bonding properties of actinyl-methoxide complexes from Uranium, Neptunium, to Plutonium using Density Functional Theory (DFT). All calculations have been carried out with different effective core potentials and the associated orbital basis set (specifically, LANL2DZ, CRENBL, and Stuttgart) for U, Np and Pu in order to examine effects of different effective core potentials and the associated orbital basis set on the calculated structure, vibration frequency, and bonding properties. The exchange correlation functional used in this work is B3LYP. The spin orbital coupling effect has also been studied for one case. Our results showed that the bond length difference among U=O=U, Np=O=Np, and Pu=O=Pu is quite small, about 1% variance, while the bond angle differs about 5% among U=O=U, Np=O=Np, and Pu=O=Pu. On the other hand, the calculated infra red frequency showed a notable difference among U, Np and Pu, with Np always the smallest, regardless of the type of effective core potential and the associated orbital basis set applied.