Redetermination of sodium cerium(III) sulfate monohydrate, NaCe(SO4)2.H2O.

The structure of sodium cerium sulfate monohydrate, NaCeIII(SO4)2.H2O, comprises distorted NaO6 octahedra, CeO9 polyhedra in the form of distorted tricapped trigonal prisms, and slightly irregular tetrahedral sulfate ions. This structure is isomorphic with that of NaLaIII(SO4)2.H2O. All bonds fall within normal limits. The sulfate ion manifested rigid-body behavior but neither of the cation complexes did. As in the previous structural analysis of the La analog [Blackburn & Gerkin (1994). Acta Cryst. C50, 835-838], the water molecule is modelled as having O-atom disorder but with an ordered H atom. Hydrogen bonds involve only sulfate O atoms as acceptors. The anisotropic atomic displacement parameters are found to be in good agreement with the corresponding parameters determined for the La analog, but in poor agreement with those previously reported for the title salt by Lindgren [Acta Chem. Scand. Ser. A, (1977), 31, 591-594]. Taken together, the data establish that the lack of correction for absorption in the previous study of the Ce salt, rather than some intrinsic property of the Ce salt, is responsible for the displacement parameter discrepancies. The absolute structure has been determined.