Homoatomic sulfur cations

A review of the recent achievements in an understanding of the synthesis, soln. behavior, structure and bonding of the homopolyat. sulfur cations. A focus is put on the developments aimed to understand exptl. observations, i.e., quantum chem. calcns. of these electronically delicate species. The synthesis of the highly electrophilic sulfur cations requires the use of very weakly basic conditions throughout, that is weakly coordinating counterions such as AsF6-, SbF6-, Sb2F11- as well as weakly basic solvents such as SO2, HF, HSO3F. Structure and bonding of the currently structurally characterized S42+, S82+, and S192+ cations are governed by pos. charge delocalization brought about by 3pv3pv, v*-v* and 3p2->3V* bonding interactions. The soln. behavior of S82+ salts, which give rise to several sulfur radical cations such as S5.+, was analyzed in detail based on (calcd.) thermodn. as well as spectroscopic considerations and hitherto unknown D3d sym. S62+ and D4h sym. S4.+ are likely players in SO2 solns. of S8(AsF6)2. [on SciFinder (R)]