An ESR Study of the Radical Cations of Tetrathiafulvalene (TTF) and Electron Donors Containing the TTF Moiety

Abstract

Abstract Hyperfine data and g factors are reported for the radical cations of tetrathiafulvalene (TTF; 1 ) and of its derivatives 2–13 . From the intense satellite spectra of 1 + – 13 + not only the coupling constants of the 33 S isotopes in the TTF moiety could be determined, but also, in favourable cases, those of the 13 C isotopes in the central double bond. The former values range from 0.370 ( 8 + ) to 0.470 mT ( 4 + ) and the latter from 0.255 ( 8 + ) to 0.360 mT ( 4 + ) in the radical cations of bis(ethylenedithio)‐TTF ( 8 + ) and tetracyano‐TTF ( 4 + ). The radical cation of TTF ( 1 + ) exhibits intermediate values, 0.425 for the 33 S and 0.285 mT for the 13 C isotopes. The spin population in 1 + – 13 + resides, to a large extent, in the central S 2 C  CS 2 part of the π‐system. It tends to increase (decrease) by substitution with electron‐accepting (donating) groups in the 2,3,6,7‐positions of TTF.