Oxidation of divalent tin in aqueous solutions of SnF2 and 3D transition metals allowed to crystallize slowly in air

Chlorides, nitrates and sulfates of M (M=Mn, Fe, Co, Ni and Zn) were dissolved in aqueous solutions of SnF₂ at M/Sn molar ratios of 0.5 to 3. No HF was used. The solutions were allowed to evaporate in air. Very small amounts of hexagonally shaped crystals of unknown materials were obtained for M=Mn, Co, Ni and Zn. Fe did not yield this phase. X-ray powder diffraction gives identical patterns for the four materials, which are therefore most likely isostructural, and showed that the products are not MSn₂F₆·6H₂O or MSnF₆·6H₂O. Tin-119 Mössbauer spectroscopy gives a single line at negative isomer shift, characteristic of [Sn(IV)F₆]^2– ions.