Heteropolytungstate complexes of the lanthanoid elements. Part III. Crystal structure of sodium decatungstocerate(IV)–water (1/30)

Abstract

Crystals of the title compound are monoclinic, space group C2/c, a= 18·14(1), b= 18·62(1), c= 18·51 (1)Å, β= 95·9(5)°, Z= 4. The heavy atoms were located by direct methods and the oxygen and sodium atoms by difference Fourier analyses, with block-diagonal least-squares refinement to R 0·083 for 2781 independent reflections measured on a diffractometer. The analysis confirms that the heteropolyanion is a heterodecatungstate, and not an octatungstate as originally reported. The cerium atom, on a two-fold crystal axis, takes two pentatungstate ligands, W₅O₁₈H^5–, each of which is derived from a W₆O₁₉^2– anion by the loss of one tungsten atom and its apical oxygen and consists of five WO₆ octahedra sharing edges. The eight oxygen atoms about the cerium define a square antiprism. The sodium cations have distorted octahedral co-ordination.