Polychalcogen cation

This means that upon oxidation of neutral chalcogens giving the polychalcogen cations, electron density is removed from the occupied rap2 lone pair orbitals.15,16 From a molecular orbital (MO) view of such interactions... 

The structures of individual polychalcogen cations and theoretically based interpretations of their bonding will now be discussed in order of increasing nuclearity n = 4-19. For more details, the reader is referred to the excellent recent review articles of Beck [19] (structures) and Passmore [13] (bonding and energetics). 

Fig. 2.7-9. Molecular structures of polychalcogen cations with ten or more atoms.

One-bond couplings have been reported for Me-Se-Te-Me (—169 2 Hz). Some polychalcogen cations and anions afford substantial one-and two-bond 2 Te, Se coupling constants (189-670 Hz). 

Fig. 10. Apparatus for the preparation and extraction of polychalcogen cation salts in liquid sulfur dioxide.

This kind of an rap2- -racr interaction may lead to a marked bond lengths alternation the extreme structural effect of such an interaction is certainly found for S7, but also other neutral and cationic polychalcogen compounds frequently exhibit this interaction. 

For this larger size of isolated polychalcogen entities only the respective neutral S11-S14 homocycles are known no evidence for other neutral or cationic species in this size has been given. S15 was not structurally characterized.82,83... 

In this chapter, we demonstrated that the restriction of building a compound with only one type of an element is not a restriction at all and a multitude of neutral, cationic as well as anionic polychalcogen structures is currently known. As expected for the more electronegative nonmetal (S) and meta metals (Se, Te), the bonding within these moieties is covalent and a small number of interactions, namely, p2-rap2 lone pair repulsion, n- and n -n bonding as well as p2- cr interactions, are sufficient to rationalize the structures and account for the bond lengths alternations or weak transannular interactions that are often found. 

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