Thermally Induced Elimination Reactions in Xerosols Derived from (Fluoroorgano)tin Compounds:  A New Efficient Way To Prepare F-Doped Tin Dioxide Materials

Trialkynyl(fluoroorgano)tins(IV) (C4H9−C⋮C)3−SnRF (1) (RF = −(CH2)2−CF3, −o-FC6H4) have been synthesized in three steps from tricyclohexyltin hydride or chloride and were characterized by multinuclear 1H, 13C, 19F, and 119Sn NMR spectroscopy. Hydrolysis of 1 yielded oxo-hydroxoorganotin oligomers soluble in acetonitrile and alcohols, where each tin atom bears a fluorinated organic group. Thermally induced β- or γ-elimination reactions, evidenced by TG/MS measurements, allowed the insertion of fluorine into the oxide network and the removal of the undesirable organics. Densification at 550 °C gave crystalline particles of SnO2 cassiterite containing the required amount of doping fluorine (4 at. %) and exhibiting an electronic resistivity (0.3 Ω·cm) lower than that previously reported (2−10 Ω·cm) for similar tin oxide materials. β- or γ-elimination processes in organotin compounds appear to be a suitable method of preparation of highly conductive nanocrystalline F-doped SnO2 materials by the sol−gel route with low contaminating carbon content.