Homopolyatomic cations preparation

The major synthetic strategies for preparing homopolyatomic cations of group 16 elements can be summarized as follows ... 

Direct Synthesis reaction of, 6 395 fluoride, 21 235, 237, 239, 249 homopolyatomic cations, 17 82 ion, stereochemistry, 2 40-41, 44-45 isocyanates, preparation, 9 158 properties, 9 157 isothiocyanates, properties, 9 177 mixed valence compounds of, 10 375-381 crystal structure of, 10 376 diffuse reflectance spectrum of, 10 380 structure of Pb," ion, 10 381 nuclear magnetic shielding, 22 224 organometallic compounds, 2 82, 88, 89 oxide, neutron diffraction studies on, 8 231-233... 

The main use of CF3SO3H in synthetic inorganic chemistry reported to date has been in preparation of binary compounds which are themselves triflates or of complexes derived from those triflates. HSO3F has been used similarly in the generation of fluorosulfates and of fluorosulfato-complexes but it has also been the medium of choice, particularly when coupled with the oxidant S206F2, in the generation and characterisation of many homopolyatomic cations and transition metal carbonyl cations, as will be shown in Sec. 11.3.4. 

During the last 10 years a number of homopolyatomic cations where x y) have been prepared and characterized. For a long time the only known example of this type of species was the mercurous... 

Salts of homopolyatomic cationic clusters now constitute a well-established class of compound— there are at least twenty-six fairly well-characterized examples. It is probable that many other elements will also be shown to form polyatomic cations. As yet reactions of these species have been little studied, and there is obviously a wide open field here awaiting exploration. Many structures of known cations, as well as those that have not yet been prepared, remain to be investigated, and there is a need for theories that can predict the stability and geometry of these cations and provide a description of the bonding. 

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. 

N. Burford, j. Passmore and J. C. P. Sanders, Chap. 2, Preparation, Structure and Energetics of the Homopoly-atomic Cations of Groups 16 and 17, in J. F. Liebman and A. Greenburg (eds.). From Atoms to Polymers Isoelec-tronic Analogies, VCH PubL, Honda, 1989, pp. 53-108. J. Passmore, Chap. 19 Homopolyatomic Selenium Cations... 

Quite recently, there was a report of the surprisingly straightforward preparation and characterization of the salt [N5]+[AsF6] containing the novel [N5]+ cation (Fig. 3), which represents only the third known example of a homopolyatomic nitrogen species that can be isolated on a macroscopic scale ... 

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