Periodic trends in actinide phosphonates: divergence and convergence between thorium, uranium, neptunium, and plutonium systems.

The hydrothermal reactions of both PuO(2)(2+) and PuO(2) with phosphonates results in the formation of Pu(IV) phosphonates. Pu(CH(3)PO(3))(2), Pu[CH(2)(PO(3))(2)](H(2)O), and UO(2)Pu(H(2)O)(2)[CH(2)(PO(3))(PO(3)H)](2) have been isolated from these reactions and structurally characterized. Pu(CH(3)PO(3))(2) contains six-coordinate Pu(IV) and adopts a structure closely related to that of alpha-Zr(HPO(4))(2).