Received 4 June 2013
The title compound, Ca[Sn(H2PO2)6], was formed after a few days when tin(II) fluoride was allowed to react with phosphinic acid at ambient conditions. The structure consists of chains of Ca2+ and Sn4+ cations in octahedral sites with -3 symmetry bridged by bidentate hypophosphite anions. The chains are hexagonally close packed along . The discovery of the compound and the successful structure refinement provides strong evidence that an isostructural compound, originally described as the mixed-valence compound, Ge2[H2PO2]6 [Weakley (1983). J. Chem. Soc. Pak. 5, 279-281], must be reformulated as Ca[Ge(H2PO2)6].
For the reaction of SnF2 with H3PO2, see: Everest (1951). For the structures of Ge2(H2PO2)6, see: Weakley (1983), and Fe2(H2PO2)6, see: Kuratieva & Naumov (2006). For the so-called Ge2(H2PO2)6 structure type, see: Bergerhoff et al. (1999); Villars et al. (2010). For Ca-O bond lengths, see: Smith & Leider (1968) and for Sn-O bond lengths, see: Yamanaka et al. (2000). Bond-valence sums were calculated using Valist (Wills, 2010)
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); 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, 2006) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CQ2005 ).
We thanks the Deutsche Forschungsgemeinschaft and the Government of Lower Saxony for funding the diffractometer.
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