The transformation ofSn(ND3)2F4 into Sn(ND2)F2. Synthesis and neutron crystal structure determination of Sn(ND2)2F2

The principles of systematics proposed in the previous paper are applied to the crystal structures with deficient fluorite-related frameworks. These frameworks are classified into ones with face-sharing fluorite modules and ones with quarter-of-face-sharing fluorite modules. It is shown that frameworks with face-sharing modules may be described using the concept of supermodule i.e. set of modules from which the whole framework may be obtained by its periodic repetition. Example compounds are considered.