Group 17 elements homoatomic polyanions

Homoatomic Polyanions of Group 14 Elements in Solid State Compounds... 

Homoatomic chains are a fascinating group of polyanions, due to the possibility to study multiple bonding of heavier main group elements in the solid state and the coordination behavior of differently charged atoms in the same molecular structure. 

Fig. 11 Homoatomic polyanions of group 15 elements in neat solids...

In the past decades, homoatomic polyanions in solid state compounds of group 14 elements have been a powerful starting material toward different kinds of chemical transformations. Recent developments, especially for nine-atom clusters, have been discussed elsewhere [5,125,126] and are not within the scope of this review. Here, we concentrate on neat solvates , which means that in addition to cation and anion... 

Fig. 13 Homoatomic polyanions of group 14 elements, which are present in solvate structures (a) tetrahedral (E = Sn, Pb) (b) nine-atom cages Eg" (n = 2-4 E = Si-Pb) (c) trigonal bipyramidal Es (E = Si-Pb)...

Having a closer look at the reported solvate structures of homoatomic polyanions of group 14 elements, it becomes evident that only clusters and no rings or chains are stable in solid state as well as in solution (Fig. 13). Higher reduced polyanions with > 5, equivalent with a charge higher than —1 per atom, are not reported in solution so far. The nine-atom species is quite well established in solutions of ammonia and ethylenediamine. Their interesting reactivity is intensely studied and is discussed elsewhere [5, 125, 126]. The less-understood cluster... 

Beside the most frequent soluble tetrel and pentel element clusters listed in Table 1, other homoatomic polyanions have been isolated from solution. An overview is given in Figs. 2 and 3 for group 14 and 15 elements, respectively, and in Table 2. The smaller tetrel clusters [Es] and [Eio] have been isolated as A-crypt salts (Fig. 2b, e, respectively), and most probably they are formed upon... 

---