Redetermination of Ce[B5O8(OH)(H2O)]NO3·2H2O

The crystal structure of Ce[B(5)O(8)(OH)(H(2)O)]NO(3)·2H(2)O, cerium(III) aqua-hydroxidoocta-oxidopenta-borate nitrate dihydrate, has been redetermined from single-crystal X-ray diffraction data. In contrast to the previous determination [Li et al. (2003 ▶). Chem. Mater.15, 2253-2260], the present study reveals the location of all H atoms, slightly different fundamental building blocks (FBBs) of the polyborate anions, more reasonable displacement ellipsoids for all non-H atoms, as well as a model without disorder of the nitrate anion. The crystal structure is built from corrugated polyborate layers parallel to (010). These layers, consisting of [B(5)O(8)(OH)(H(2)O)](2-) anions as FBBs, stack along [010] and are linked by Ce(3+) ions, which exhibit a distorted CeO(10) coordination sphere. The layers are additionally stabilized via O-H⋯O hydrogen bonds between water mol-ecules and nitrate anions, located at the inter-layer space. The [BO(3)(H(2)O)]-group shows a [3 + 1] coordination and is considerably distorted from a tetra-hedral configuration. Bond-valence-sum calculation shows that the valence sum of boron is only 2.63 valence units (v.u.) when the contribution of the water mol-ecule (0.49 v.u.) is neglected.