Polyatomic sulfur cations

Seel and co-workers (72) have reported that Sgl +AsEg gives a mixture of sulfur polyatomic cations and SF3 AsFe on warming to 100°, or at room temperature in the presence of AsFg. 

Thus, sulfur is the element richest in allotropes,1 while tellurium holds the record for the number of positively charged polyatomic cations. Moreover, tellurium (and to a lesser extent Se) is at the border between a nonmetal and a metal thus, solid grey Se and Te are semiconductors and especially... 

As early as 1804, it was reported that sulfur dissolves in oleum to give brown, green or blue solutions [76]. As for solutions of sulfur in liquid ammonia, the nature of the colored species has been controversial. It was shown 30 years ago that sulfur can be oxidized with S2O6F2, AsFg, or SbFg in various solvents (H2SO4, HFSO3, HF, oleum) to polyatomic cations Sg +,... 

Polyheteroatom Cations. So far, only studies on homopolyatomic cations of oxygen, sulfur, selenium, and tellurium have been discussed. Most of them were of the type X,21. There is a new class of polyatomic cations that comprise two or more heteroatoms. 

Sulfur may be oxidized by different oxidizing agents to yield a variety of polyatomic cations. The currently known species that have been characterized by X-ray diffraction are S, Sg+, and S -, the structures of which are shown in Fig. 16.4.2. 

Like their sulfur congener, selenium and tellurium can form polyatomic cations and anions in many compounds. 

In such a strong oxidizing medium it is also possible to produce polyatomic cations of sulfur ... 

Table 12-3 Polyatomic Cations of Sulfur, Selenium, and Tellurium...

It has been found that selenium may be oxidized by several different oxidizing agents to a variety of polyatomic cations. In 1827, Magnus observed that sulfuric acid dissolved selenium to give green or yellow solutions. It has been shown that these solutions contain the polyatomic cations Sc4 + and Seg +. ... 

The colored solutions produced on dissolving elemental selenium in sulfuric acid were first observed by Magnus in 1827 80). Since then a number of workers have investigated the nature of selenium solutions in sulfuric acid, oleum, and sulfur trioxide, providing 81) a substantial amount of data but little understanding of the system. Recently, it has been shown that these solutions contain the yellow Se and green Seg " polyatomic cations 82). 

Pg (126) have been reported as products of the reaction of the elements with S2O6F2 HSO3F or with oleum. However, the ultraviolet spectra reported for these species are very similar to those found for Sg , or S4 ", and it seems very probable that antimony, arsenic, and phosphorus reduce HSO3F and H2S2O7 to elemental sulfur, which is then oxidized to Sig " ", Sg, or 84 +. Indeed, it has been demonstrated that elemental sulfur is one of the products of the reduction of oleum by antimony (123). Thus there is at present no reliable evidence for any polyatomic cations of P, As, or Sb, with the exception of (Sb ) . 

Oxidation of elemental sulfur and selenium with SbFs leads to the formation of doubly charged polyatomic cations [26]. These cations can react with polyfluorinated arenes to form diaryl sulfides or selenides (Eq. 12) [27]. 

The preparation and properties of homopolyatomic cations of the Group VI elements have been reviewed recently.1 The general method described below, involving the oxidation of elemental sulfur, selenium, and tellurium with either antimony pentafluoride or arsenic pentafluoride in liquid sulfur dioxide, is convenient for the preparation of compounds containing these polyatomic cations. The procedure is basically that briefly described previously2 for the preparation of Se8(Sb2F j i )2. 

As early as 1804 solutions of non-metals such as sulfur and iodine in oleums were reported to produce highly colored solutions but the nature of the solutes was unknown. From the mid 1960s, Gillespie s group adduced reliable evidence to indicate that solutions such as these and others in HS03F and HF contained the polyatomic halogen cations It, if", IJ, If, Brf and Brf and the chalcogen cations listed in Table 2. 

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