Electron counting Zintl ions, 451

A large number of nine-vertex Zintl ions are known (see details in the next section). Those having electron counts of 32 + 8 = 40 (Eg4-, E = Si, Ge, Sn, Pb), do... 

K4Ge4, can be described as a polyanionic compound (as a Zintl phase also) containing the ion Ge44. This tetrahedral ion can be considered a naked (that is without any ligands bounded to the vertices) tetrahedral cluster formed by a main group element (that is Ee = 5 3 = 5X4 = 20). The electron count, on the basis of the Ge valence electrons and of the ion charge results in Ee = 4 X 4 + 4 = 20. 

Worked example 15.5 Electron counting in heteroatomic Zintl ions... 

Correlations between structure and electron counting for homo and heteronuclear Zintl ions are described in Table 4.19. 

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