Promising density functional theory methods for predicting the structures of uranyl complexes

Abstract

The structural parameters of uranyl complexes may provide important hints for understanding the electronic structure of the U–X (ligand) bond. The present study aims to identify a reliable theoretical method to simulate the structures of different uranyl complexes. Examining the performance of different relativistic effective core pseudopotentials (RECPs) and different density functional theory (DFT) methods, we found that the overall performances of BB1K/(SDD-MWB60:6-311G(d,p)) (M2-B1) and LC-BLYP/(SDD-MWB60:6-311G(d,p)) (M7-B1) methods are better than all the other examined ones (including the popular B3LYP method). Good linear correlations have been achieved between the calculation results with M2-B1 or M7-B1 and the experimental ones (X-ray crystal structure). The R² values of both these methods are about 0.985, and the SD values are both about 0.05 Å for 68 U–X bond distances. On this basis, the preliminary ligand structure-binding ability analysis of U–O bonds and the elucidation of the binding mode of the azide group in the concerned U–N(azide) compound have been provided.