The synthesis, structures, optical properties, and electronic structures of the tetraphenyltetrathiaporphyrin dication (S 4TPP 2+, 6) and tetrakis(pentafluorophenyl)tetrathiaisophlorin (S 4F 20TPP, 7) are reported. S 4TPP 2+ (6) and S 4F 20TPP (7) were synthesized by acid-catalyzed condensation of the corresponding hydroxylmethylthiophene, followed by oxidation. The electronic structures of S 4TPP 2+ (6) and S 4F 20TPP (7) were analyzed by using UV/Vis-absorption spectroscopy and by magnetic /ular dichroism (MCD) spectroscopy and the bands were assigned by using time-dependent density functional theory (TD-DFT) and ZINDO/s calculations. A red-shift of the Q bands of S 4TPP 2+ (6) is observed relative to the spectra of tetraphenylporphyrins because a destabilization of the HOMO leads to a narrower HOMO-LUMO band-gap. Michl's perimeter model was used to assign the absorption bands and MCD spectra of S 4F 20TPP (7). Current-density maps and nucleus-independent chemical-shift (NICS) calculations of S 4TPP 2+ (6) and of a model compound predict marked modification to the diamagnetic ring current, whilst nonaromatic character is predicted for S 4F 20TPP (7).
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