Preference for Nitrogen versus Oxygen Donor Coordination in Uranyl- and Neptunyl(VI) Complexes

The first actinyl phosphinimine complexes have been synthesized and, in the case of uranium, exhibit strong U−N interactions. Competition reactions clearly demonstrate a surprising preference for R3PNH ligands over R3PO in the system [AnO2Cl2(R3PX)2] (An = UVI, NpVI; R = Ph, Cy; X = O, NH). Spectroscopic evidence for N-donor coordination to [NpO2]2+ in solution indicates chemical similarities to the [UO2]2+ moiety.