Structures built from tetrahedra and octahedra

Structures which can be represented as assemblies of tetrahedral and octahedral coordination groups are very numerous. For example, they include all oxy-salts in 

We have already noted examples of structures in which tetrahedra or octahedra share various numbers of vertices. Structures in which tetrahedra and octahedra share only vertices form an intermediate group  

Some of the simplest of this large family of structures are set out in Table 5.7 the structures are described in later chapters. The table shows the number of octahedra (o) with which each tetrahedron (t) shares vertices, the relative numbers of tetrahedra and octahedra, the contributions to the chemical formula made by each (a shared vertex counting as X and an unshared vertex as X), the formula, and examples of compounds with the structure. 

Structures in which tetrahedral AX4 and octahedral BX groups share only vertices 

Structures in which an element exhibits both tetrahedral and octahedral coordination 

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We now survey structures built from tetrahedra and octahedra. A survey of the kind attempted in this chapter not only emphasizes the great number and variety of structures arising from such simple building units as tetrahedra and octahedra but also draws attention to ... 

Some of the simpler structures of this type were noted in the discussion in Chapter 5 of structures built from tetrahedra and octahedra. Here we describe some of the structures listed in Table 5.7 (p. 190) and also some more complex structures of the same general type. The composition depends on the relative numbers of... 

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