THE ELECTRON SPIN RESONANCE OF THE RADICAL CATIONS OF P-TERPHENYL, TRIPHENYLENE AND TRIPTYCENE

Article abstract of DOI:10.1002/recl.19881070317

The ESR spectra of the radical cation of p-terphenyl (1), triphenylene (2), and triptycene (3) have been investigated in fluid solution.

.The hyperfine coupling constants of 1^+. are in line with those predicted on the simple Hueckel-McLachlan-McConnel model, and suggested that it is a simple near planar monomeric species.The radical cation from 2 formed an adduct with 2 and only the spectrum of the dimeric species 2₂^+. could be detected.The ESR spectrum of 3^+. is in accord with that predicted for the form of the SOMO, the bridgehesd protons showing only a very small hyperfine coupling.When 3^+. is generated photolytically the presence of Hg(OCOCF3)2 or Tl(OCOCF3)3, the ESR spectra indicate that subsequent mercuration or thallation of 3^+. occurs in the β-position.When AlCl3 is used as the reagent, 3^+. can appereantly undergo a retro-Diels-Alder reaction, and the spectrum of 3^+. becomes replaced by that of the anthracene radical cation.