Zintl counting scheme

Qualitatively, the semiconducting behavior of the germanium- and tin-based cationic clathrates can be rationalized within the frames of the Zintl counting scheme, assuming the reversed host-guest polarity. In traditional Zintl phases of a general... 

Several methods are available to analyze the electronic structure and discuss the chemical bonding of molecules and solids in a quantitative as well as qualitative way. Various levels of sophistication exist. From the chemist s perspective, electron counting schemes, such as the Zintl-Klemm (Klemm 1958 Schafer and Eisenmann 1981, von Schnering 1985), Mooser-Pearson (Mooser and Pearson 1956, 1960), or the (8 — N) rule (Kjekshus and Rakke 1974), which were frequently applied in the preceding section, are useful tools to understand relationships between composition and structure, structure and bonding, bonding and properties. Molecular orbital... 

Here ln(l) is two-coordinate while ln(2) and ln(3) are four-coordinate (there are two ln(2) and ln(3) sites for every single ln(l) atom). As the density of states plots show, this compound is metallic. A plot of the In populations is shown on the left side where the solid line, dashed line and dotted line refers to the ln(l), ln(2), and ln(3) atoms, respectively. The DOS plot on the right side shows the projected contributions to the X (solid line), y (dashed), and z (dotted) p AOs of the In atoms. How does this compound fit into the Zintl-Klemm counting scheme What do the crystal orbitals around the Fermi level look like ... 

---