Theoretical study of the microhydration of mononuclear and dinuclear uranium(VI) species derived from solvolysis of uranyl nitrate in water

Abstract

The structures and energetics of mononuclear and dinuclear uranium species formed upon speciation of uranyl(VI) nitrate, UO(2)(NO(3))(2), in water are investigated by quantum chemistry using density functional theory and the wavefunction-based methods (MP2, CCSD, CCSD(T)). We provide a discussion of the basic coordination patterns of the various mono- and dinuclear uranyl compounds [(UO(2))(m)(X,Y)(2m-1)(H2O)(n)](+) (m = 1, 2; n = 0-4) found in a recent mass spectrometric study (Tsierkezos et al., Inorg Chem 2009, 48, 6287). The energetics of the complexation of the uranyl dication to the counterions OH(-) and NO(3) (-) as well as the degradation of the dinuclear species were studied by reference to a test set of 16 representative molecules with the MP2 method and the B3LYP, M06, M06-HF, and M06-2X DFT functionals. All DFT functionals provide structures and energetics close to MP2 results, with M06 family being slightly superior to the standard B3LYP functional.

Reduction from copper(II) to copper(I) upon collisional activation of (pyridine)2CuCl+

“…The changes in geometry of the pyridine ligand upon binding to Cu + are minor and are largest for monoligated (py)Cu + while decreasing with increasing number of ligands. The CuN bond lengths in (py)Cu + and (py) 2 Cu + are practically the same, whereas it is slightly shorter in (py)CuCl + , which can be understood as a result of an increased electrostatic attraction between copper and pyridine due to the presence of the electron‐withdrawing chloro ligand 14, 62–64. Coordination of another pyridine molecule to both (py) 2 Cu + and (py)CuCl + causes elongation of the CuN bond, which can be attributed to increased steric demands.…”

Structural Analysis of the Complexation of Uranyl, Neptunyl, Plutonyl, and Americyl with Cyclic Imide Dioximes

“…Utilizing the B3LYP functional, the Stuttgart RSC 1997 ECP and basis set for U and the 6-311++G** basis set for the non-U atoms is commonly accepted to provide accurate geometries for uranyl compounds. − A previous study of [An­(NO 3 )] 2+ structures established that utilizing the 6-31G*, cc-pVDZ, 6-311++G**, cc-pVTZ, and cc-pVQZ basis set for non-An atoms, the Stuttgart RSC 1997 ECP and associated basis set for the actinides include all of the basis functions in the basis set, while changing the functional (LDA, TPSS, B3LYP, PBE0, and B972) predicted structures with an An–O distance of less than 0.03 Å and an O–An–O angle difference of less than 1° . In the current study, the strongly constrained and appropriately normed semilocal (SCAN) density functional is also included as it had not yet been tested for actinides.…”