Received 6 December 2011
The crystal structure of the title compound, Ce[B4O6(OH)2]Cl, is built from polyborate sheets parallel to the (001) plane. These sheets stack along the  direction and are linked by Ce atoms exhibiting an CeO8Cl2 coordination sphere. O-HO and O-HCl hydrogen bonds additionally stabilize the structural set-up. The polyborate sheet is made up of zigzag borate chains running along the  direction. These zigzag chains are interconnected by shared O-vertices, resulting in a two-dimensional layer with nine-membered rings. All B and O atoms (except for the terminal OH atoms) lie in the nearly planar sheets of polyborates, leading to their isotropic atomic displacement parameters being significantly smaller than usual. This may be attributed to the fact that the atomic displacement parameters correlate not only with their atomic masses but with their coordination environments also.
For background to borate compounds and their applications, see: Burns et al. (1995); Chen et al. (1985); Zhao et al. (1990); Sun, Sun et al. (2010); Sun, Zhou et al. (2010). For isotypic structures, see: Belokoneva et al. (2002) for Ln[B4O6(OH)2]Cl (Ln = Pr, Nd).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2011) and ATOMS (Dowty, 2004); software used to prepare material for publication: SHELXL97.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2495 ).
This work was supported by the National Natural Science Foundation of China (grant No. 40972035), the Natural Science Foundation of Fujian Province of China (grant No. 2010 J01308) and the Scientific and Technological Innovation Platform of Fujian Province (grant No. 2009 J1009).
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