IUCr journals

Pseudoatoms and preferred skeletons in crystals

Acta Cryst. (2007). B63, 339–345 [doi:10.1107/S0108768107019167]

[CsLiSO4]In CsLiSO4, cations form a cotunnite-like structure with trigonal prisms of Li and Cs atoms (red lines) centred by S. If Cs donates one electron to Li, the (LiS)– subarray (a pseudo-II–VI compound) forms a four-connected net of the SrAl2-type (blue contacts).
The GZKC (generalized Zintl–Klemm concept) seems to be the universal key to interpret and understand crystal structures of alloys as well as cation arrays of oxides. This generalization suggests a concerted electron transfer between cations (even if they are of the same kind) to produce cationic skeletons mostly coincident with either elements or pseudo-elements of group 14 as if some sort of “(IV)–(IV) rule” holds in the formation of a given compound. In oxides, the O atoms locate close to the bonding zones. 

A. Vegas and V. García-Baonza