Abstract
Upon ionization of the P~4~S~3~I~2~ molecule with Ag[Al(OR)~4~], a highly reactive sulfonium cation P~4~S~3~I^+^ is generated (NMR simulated and assigned). At β80βΒ°C this cation reacts with additional P~4~S~3~I~2~ to give either an iodophosphonium P~4~S~3~I~3~^+^ cation (NMR simulated and assigned) and P~4~S~3~ or to give several isomers of a metastable compound that is probably P~8~S~3~I~3~^+^. This mixture decomposes at 0βΒ°C to give only three isomers of the spirocyclic P~7~S~6~I~2~^+^ cage cation (^31^P NMR simulated and assigned, Xβray of one isomer, IR assigned). The oxidation of the [Ag(P~4~S~3~)~2~]^+^ complex by I~2~ also resulted in the formation of P~7~S~6~I~2~^+^, but with more byβproducts. The spirocyclic 15βatom cage of P~7~S~6~I~2~^+^ has no precedent and contains the first phosphonium center bonded only to P and S atoms. This structural element gives the first experimental clue as to how formal chargeβbearing elements in the still unknown class of binary Pο£ΏCh (Ch = chalcogen) or homopolyatomic P cations may be constructed.