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

Date Published: May 01, 2012

Publisher: International Union of Crystallography

Author(s): Wei Sun, Teng-Teng Zhu, Biao-Chun Zhao, Ya-Xi Huang, Jin-Xiao Mi.


The crystal structure of Ce[B5O8(OH)(H2O)]NO3·2H2O, cerium(III) aqua­hydroxidoocta­oxidopenta­borate 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 [B5O8(OH)(H2O)]2− anions as FBBs, stack along [010] and are linked by Ce3+ ions, which exhibit a distorted CeO10 coordination sphere. The layers are additionally stabilized via O—H⋯O hydrogen bonds between water mol­ecules and nitrate anions, located at the inter­layer space. The [BO3(H2O)]-group shows a [3 + 1] coordination and is considerably distorted from a tetra­hedral 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 mol­ecule (0.49 v.u.) is neglected.

Partial Text

For a previous structural study of the title compound, see: Li et al. (2003 ▶). For the La analogue, see: Li et al. (2005 ▶). For the bond-valence method, see: Brown (2002 ▶). For related structures, see: Sun et al. (2010 ▶, 2012 ▶). For a review on geometrical parameters of borate groups, see: Zobetz (1982 ▶, 1990 ▶). FBBs in borate crystal chemistry were reviewed by Burns et al. (1995 ▶).