Crystal structures of salt hydrates: a determination of sodium thiosulphate pentahydrate by x-ray diffraction

Abstract

The determination of the structure of sodium thiosulphate pentahydrate is a problem possessing three principal points of interest.

No structure determination of a compound containing the S₂O₃" group has yet been reported. Its shape, however, has been predicted, and confirmation would complete our knowledge of the structures of all the sulphur- oxygen groups by X -ray diffraction.

It will, in addition to this, provide a further example of the way in which water of crystallisation is utilised in crystal structures.

Thirdly, the problem will be of interest purely in relation to the technique of structure-determination. The relative positions of the atoms in such a compound cannot be predicted, with the exception of the thiosulphate group. In other -orris, no chemical knowledge of the shape of the molecule is available to assist the crystallographer, apart from interatomic distances found in other structures.

It as decided at the commencement of this work that a solution by purely crystallographic means would be attempted. X -ray analysis is obviously a more powerful tool in the elucidation of the structure of matter if it can succeed without the assistance of other evidence.

This thesis provides some evidence of the possibility of such work.