Structural and electronic characteristics of thienyl(aryl)iodonium triflates.

A general strategy toward the synthesis of aryliodonium triflate salts has been exploited to afford derivatives that incorporate thiophene and bithiophene components. Both mono- and bis(iodonium) salts have been realized, and a series of bithienyl(aryl)iodonium triflates with increasingly electron-withdrawing substituents on the aryl moiety have been synthesized. X-ray crystallographic analysis of four derivatives (4a, 4b, 6b, and 8c) demonstrates that the solid-state organization of these salts incorporates extensive networks of secondary bonding interactions between the cationic iodonium centers and the triflate counterions. UV-vis spectroscopic analysis shows that the electronic interactions between pendent aryl and heteroaryl groups across the iodonium center can be dictated by substitution. Furthermore, the energy of the HOMO-LUMO gap decreases substantially in weakly or noncoordinating solvents.