Electronic Structures of Uranyl(VI) Carbonate Complexes in the Aqueous Phase

A systematic study of series of non-hydrated and hydrated Cn/m uranyl carbonate complexes (n is number of carbonate ligands, and m is number of water molecules) in the aqueous phase was carried out using relativistic density functional theory. The conductor-like screening model was used to calculate solvent effects. The zeroth-order regular approximation was used to account for scalar relativistic effects and spin-orbit coupling relativistic effects. Time-dependent density functional theory with the inclusion of spin-orbit coupling relativistic effects was used to calculate electronic transitions using the statistically averaged orbital potentials. The results indicate that carbonate ligands play an important role in the geometric and electronic transition properties of the complex. The stability of the C3/0 carbonate complex in the aqueous phase may be attributed to the involvement of 5f components in the highest occupied bonding orbital. The addition of carbonate ligands caused a blue shift in the maximum wavelength and high intensity absorptions in the near visible region.