Tin(IV) fluoride is a chemical compound of tin and fluorine with the chemical formula SnF<sub>4</sub>. It is a white solid. As reflected by its melting point above 700 ðC, the tetrafluoride differs significantly from the other tetrahalides of tin.
SnF<sub>4</sub> can be prepared by the reaction of tin(IV) chloride with anhydrous hydrogen fluoride:
When treated with alkali metal fluorides (e.g. KF), tin(IV) fluoride forms hexafluorostannates:
In K<sub>2</sub>SnF<sub>6</sub>, tin adopts an octahedral geometry.
Otherwise, SnF<sub>4</sub> behaves as a Lewis acid forming a variety of adducts with the formula L<sub>2</sub>÷SnF<sub>4</sub> and L÷SnF<sub>4</sub>.
Unlike the heavier tin tetrahalides, which contain tetrahedrally coordinated tin, tin(IV) fluoride contains octahedrally coordinated tin. The octahedra share four corners. There are two terminal, unshared, fluorine atoms trans to one another. The melting point of SnF<sub>4</sub> is much higher (700 ðC) than the other tin(IV) halides: (SnCl<sub>4</sub>, âÂÂ33.3 ðC; SnBr<sub>4</sub>, 31 ðC; SnI<sub>4</sub>, 144 ðC). The structure can also be contrasted with the tetrafluorides of the lighter members of group 14, (CF<sub>4</sub>, SiF<sub>4</sub> and GeF<sub>4</sub>), all of which in the solid state form molecular crystals.