Calcium hexa­kis(dihydrogen­phosphito)­stannate(IV), Ca[Sn(H(2)PO(2))(6)], with some remarks on the so-called Ge(2)(H(2)PO(2))(6) structure type

The title compound, Ca[Sn(H(2)PO(2))(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 Ca(2+) and Sn(4+) cations in octa­hedral sites with -3 symmetry bridged by bidentate hypophosphite anions. The chains are hexa­gonally close packed along [001]. The discovery of the compound and the successful structure refinement provides strong evidence that an isostructural compound, originally described as the mixed-valence compound, Ge(2)[H(2)PO(2)](6) [Weakley (1983 ▶). J. Chem. Soc. Pak. 5, 279–281], must be reformulated as Ca[Ge(H(2)PO(2))(6)].