Stable 1H-Benzo[c]thio- and 1H-Benzo[c]selenophen-2-ium Tetrafluoroborates: Insight into Electronic Structures, Electrochemical Behavior, and Reactivity.

The synthesis of 1H-benzo[c]thio- and 1H-benzo[c]selenophen-2-ium tetrafluoroborates by the reaction of triphenylcarbenium tetrafluoroborate with 1-ethylidene-1,3-dihydrobenzo[c]thiophene or 1-ethylidene-1,3-dihydrobenzo[c]selenophene, respectively, is reported. The electronic structure of these novel 1H-benzo[c]chalcogenophenium salts was examined on the basis of their electronic spectra, whereby transitions were assigned in agreement with theoretical calculations. Electrochemical measurements revealed irreversible one-electron reduction waves for these 1H-benzo[c]chalcogenophenium salts.