Synthesis and crystallographic study of a new composite of assymetric coordination of uranium(IV) linked to two ligands of the polytungstate type [(H3SBIIIW17O59)UIV(HW5O18)]11-

The heteropolytungstate [((H3SbW17O59)-W-III)U-IV(HW5O18)](11-) was prepared using sodium tungstate and uranium(IV) fluoride or chloride. The crystallographic study shows a uranium(IV) atom at the centre of a square antiprism. It is bound by four oxygen atoms to a (H3SbW17O59)-W-III ligand and by four other oxygen atoms to a HW5O18 ligand. The unit cell is centered triclinic: a =13.4229(10), b =19.1285(12), c =19.3562(11), alpha =92.227(5), beta =98.722(6), gamma =96.378(6), V=4874(1) A(3). (c) 2005 Academie des sciences. Publie par Elsevier SAS. Tous droits reserves.