Abstract: | Selenostannates from Aqueous Solutions: Preparation and Structure of Na4SnSe4 · 16 H20 Pure selenostannates(IV) are prepared from aqueous solutions by reaction of SnSe2, with alkali selenides, strictly excluding oxygen. Na4SnSe4 · 16 H2O, being obtained from stoicheo-metric 1:2 quantities, is characterized by a complete X-ray structure analysis and by vibrational spectra. The compound is monoclinic (P21/m) with a = 8.673(3), b = 16.563(4), c = 8.647(2) Å, β = 92.10(2)°, Z = 2; it contains isolated tetrahedral SnSe44? ions Sn? Se 2.504(2)?2.527(2) Å, Se? Sn? Se 106.6(1)?111.1(1)°] which are in contact to the hydrated octahedral Na(OH2)6]+ ions through Se…?H? O bridges within an extensive hydrogen bridge system. The stretching vibrations of the SnSe44? ion are observed at 195 (n?1) and 252 cm?1 (n?3). The stretching force constant is approximately 1.59 mdyn/Å. |