Role of the uranyl oxo group as a hydrogen bond acceptor.

Density functional theory calculations have been used to evaluate the geometries and energetics of interactions between a number of uranyl complexes and hydrogen bond donor groups. The results reveal that although traditional hydrogen bond donors are repelled by the oxo group in the UO(2)(OH(2))(5) species, they are attracted to the oxo groups in UO(2)(OH(2))(2)(NO(3))(2), UO(2)(NO(3))(3), and UO(2)Cl(4) species. Hydrogen bond strength depends on the equatorial ligation and can exceed 15 kcal mol(-1). The results also reveal the existence of directionality at the uranyl oxo acceptor, with a weak preference for linear U═O---H angles.