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). Pu[CH(2)(PO(3))(2)](H(2)O) forms a novel three-dimensional network with seven-coordinate Pu(IV) and chelating/bridging [CH(2)(PO(3))(2)](4-) anions. The heterobimetallic U(VI)/Pu(IV) diphosphonate, UO(2)Pu(H(2)O)(2)[CH(2)(PO(3))(PO(3)H)](2), also forms a three-dimensional network. To complete the An[CH(2)(PO(3))(2)](H(2)O)(n) (An = Th, U, Np, Pu; n = 1, 2) and UO(2)An(H(2)O)(2)[CH(2)(PO(3))(PO(3)H)](2) series, Th[CH(2)(PO(3))(2)](H(2)O)(2) and UO(2)Th(H(2)O)(2)[CH(2)(PO(3))(PO(3)H)](2) have also been prepared. These compounds are isostructural with their Np(IV) analogues.