Synthesis, crystal structure, and properties of sodium heptafluorodiantimonate(III) hydrate (NaSb2F7·H2O)

The structure is composed of Na+ cations, H2O molecules, and asymmetric dimeric complex anions [Sb2F7]−. The anions are formed from two trigonal bipyramids [SbEF4], in which E is a lone electron pair of antimony(III) atoms linked through the bridge fluorine atom. •A new complex compound sodium heptafluorodiantimonate(III), NaSb2F7·H2O was prepared.•The structure is built of Na+-cations, H2O molecules, and asymmetric dimeric complex [Sb2F7]−-anions.•The 121,123Sb NQR spectra of NaSb2F7·H2O indicate to the presence of the two types of antimony atoms in [Sb2F7]−-anion. A new compound NaSb2F7·H2O (I) has been synthesized from aqueous solutions of NaSCN and SbF3 (components molar ratio 0.5:1) and investigated by means of the methods of chemical, X-ray structural, and thermal analysis and IR, 121,123Sb NQR, and 1H, 19F NMR spectroscopy. The structure of I is composed of Na+ cations, H2O molecules, and asymmetric dimeric [Sb2F7]− complex anions. The anions are composed of two trigonal [SbEF4] bipyramids, in which Е is a lone electron pair of antimony(III) atoms linked through the bridge fluorine atom. Complex anions in the structure are linked through secondary Sb⋯F bonds (2.628–3.344Å), NaF bonds (2.270–2.387Å), and OH⋯F hydrogen bonds (2.727–2.837Å) into a framework. In the temperature range 90–150K, the compound I manifests piezoelectric properties in the radio-frequency field. The complex fluoride sublattice remains rigid in the temperature range 150–343K in accordance with the 19F NMR data. Upon recrystallization from water and heating in the temperature range 343–423K, the substance under study decomposes with the formation of stable complexes NaSb3F10 and NaSbF4 known from the literature.