The structure of cerium(IV) bis-(phosphite), Ce(HPO3)2, has been solved by single-crystal X-ray diffraction and has trigonal (P-3m1) symmetry. The cerium(IV) cation exhibits site symmetry -3m. and is octa-hedrally coordinated by O atoms of the phosphite ligands (point group symmetry 3m.). The highly symmetrical compound has a layered structure parallel to the ab plane, and is closely related to zirconium(IV) bis-(phosphite) solved via powder X-ray diffraction with trigonal (P-3 symmetry. Structural details of the two compounds are comparatively discussed.
Keywords: cerium(IV); crystal structure; phosphite.