Tin(IV) fluoride


Tin fluoride is a chemical compound of tin and fluorine with the chemical formula SnF4. It is a white solid. As reflected by its melting point above 700 °C, the tetrafluoride differs significantly from the other tetrahalides of tin.

Synthesis and reaction

SnF4 can be prepared by the reaction of tin(IV) chloride with anhydrous hydrogen fluoride:
When treated with alkali metal fluorides, tin fluoride forms hexafluorostannates:
In K2SnF6, tin adopts an octahedral geometry.
Otherwise, SnF4 behaves as a Lewis acid forming a variety of adducts with the formula L2·SnF4 and L·SnF4.

Structure

Unlike the heavier tin tetrahalides, which contain tetrahedrally coordinated tin, tin 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 SnF4 is much higher than the other tin halides:. The structure can also be contrasted with the tetrafluorides of the lighter members of group 14,, all of which in the solid state form molecular crystals.