Fluxional motions and internal rotational barriers of water molecules bound to , , and

We have computed the torsional tunneling barriers for water molecules bound to actinyl ions, UO 2 2 + , NpO 2 + , and PuO 2 2 + using high-level relativistic computations in aqueous solution. We show that the barriers drop substantially as a function of number of water molecules, which could assist facile exchange of water molecules from the solvent to the complex. Our findings are consistent with the 17O dynamical NMR studies of Farkas et al.