Fluorostannates(II): the non-transition-metal(II) derivatives of the complex tin(II) fluoride ions

Abstract

The aqueous and molten SnF₂–MF₂(M = Mg, Ca, Sr, Ba, and Pb) systems have been studied and the preparation of the crystalline trifluorostannates(II) Sr(SnF₃)₂, Ba(SnF₃)₂, PbFSnF₃, Sr₂Sn₂NO₃F₇,2H₂O, and Pb₂SnNO₃F₅,2H₂O described. The infrared and ¹¹⁹Sn Mössbauer spectra of these materials are consistent with the presence of the SnF₃^– ion in all of them. There is no evidence for tin–nitrate bonding in the nitrate-containing phases but there is an increase in the ionic character of the Sn–F bonds compared with the metal(II) trifluorostannates(II). No derivative of the Sn₂F₅^– ion was isolated from aqueous solutions but features attributable to such compounds were found in the phase diagrams of the molten systems, and the solid complexes Sr(Sn₂F₅)₂ and Ba(Sn₂F₅)₂ were prepared.