Meet the Cerium(IV) Phosphate Sisters: CeIV(OH)PO4 and CeIV2O(PO4)2.

Two novel cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO4, and cerium(IV) oxidophosphate, Cе2O(PO4)2, which were shown to complement the classes of isostructural compounds M(OH)PO4 and R2O(PO4)2, where M = Th, U and R = Th, U, Np, Zr. Cе2O(PO4)2 oxidophosphate is formed by elimination of H2O from the crystal structure of Ce(OH)PO4 during its thermal decomposition. The structures of Ce(OH)PO4 and Cе2O(PO4)2 are related to each other with the same Cmce space group and close unit cell parameters (а = 6.9691(3) A, b = 9.0655(4) A, с = 12.2214(4) A, V = 772.13(8) A3, Z = 8; а = 7.0220(4) A, b = 8.9894(5) A, с = 12.544(1) A, V = 791.8(1) A3, Z = 4, respectively).