α,ω-Bis(trichlorostannyl)alkanes as Bis(monodentate) lewis acids toward halide ions

The reactions between X₃Sn(CH₂)_<i>n</i>SnX₃ (X = Cl, Br; _<i>n</i> = 1, 3, 4, 8) and halide in solution are described. ¹¹⁹Sn NMR spectroscopy (CD₂Cl₂) indicates formation of five-coordinate dinuclear 1:2 adducts, [X₄Sn(CH₂)_<i>n</i>SnX₄]^2-, with chloride and bromide. A trigonal-bipyramidal geometry has been confirmed in the solid state for the compound having X = Cl and _n = 4. In contrast, fluoride reacts with X₃Sn(CH₂)_<i>n</i>SnX₃ to give six-coordinate tin species, [F₅Sn(CH₂)_<i>n</i>SnF₅].^4- There was no evidence indicating that the tin atoms could act as a bidentate acid.<br />