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

Two new cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO4 , and cerium(IV) oxidophosphate, Ce2 O(PO4 )2 , which were shown to complement the classes of isostructural compounds M(OH)PO4 and R2 O(PO4 )2 , where M=Th, U and R=Th, U, Np, Zr. Ce2 O(PO4 )2 oxidophosphate is formed by elimination of H2 O from the crystal structure of Ce(OH)PO4 during its thermal decomposition. The structures of Ce(OH)PO4 and Ce2 O(PO4 )2 are related to each other with the same Cmce space group and similar unit cell parameters (a=6.9691(3) Å, b=9.0655(4) Å, c=12.2214(4) Å, V=772.13(8) Å3 , Z=8; a=7.0220(4) Å, b=8.9894(5) Å, c=12.544(1) Å, V=791.8(1) Å3 , Z=4, respectively).