Synthesis, Optical Properties, and Electronic Structures of Tetrakis(pentafluorophenyl)tetrathiaisophlorin Dioxide

The synthesis, structure, optical and redox properties, and electronic structure of tetrakis(pentafluorophenyl)tetrathiaisophlorin dioxide ( 12 ) are reported. Oxidation of tetrakis(pentafluorophenyl)tetrathiaisophlorin ( 11 ) with dimethyldioxirane afforded the oxidized product, which was the tetrathiaisophlorin with two thiophene 1‐oxide moieties ( 12 ). More significant nonplanarity and greater bond length alternation in 12 than those of 11 were observed by X‐ray structural analysis. The absorption spectrum of 12 contains two bands at λ =348 and 276 nm, with a weak tail that extends to λ ≈650 nm. Analysis of the magnetic circular dichroism spectrum of 12 , based on Michl's 4 N ‐perimeter model and molecular orbital calculations, indicate that the broad band at λ =348 nm appears to contain N 2 and P 2 bands, and 12 is classified as a 4nπ system, similar to 11 . The nuclear‐independent chemical shift values and 1 H NMR spectroscopy data indicate that 12 has more antiaromatic character than 11 .