| Abstract
| - A family of triads composed of C60 attached by a rigid spacer to two identical TTF moieties hasbeen synthesized, and some of the isomers have been isolated and characterized by UV-visspectroscopy, LDI-TOF-MS, and HMBC NMR spectroscopy. AM1 semiempirical calculations of thedipolar moments and the heats of formation of the different isomers have been carried out in orderto verify their assignments. Oxidation and reduction of the triads affords the derived radical ionsystems, TTF+•−C60−TTF+• and TTF−C60-•−TTF, which were studied by EPR spectroscopy. Spindensity distributions of these radical cations and radical anions show that the unpaired electron islocated mainly on the TTF and fullerene moieties, respectively. However, while the EPR signalsobtained from the radical cations are very similar for all the isomers, the structured signals observedfor the radical anions arising from the coupling of the unpaired electron with the hydrogen atomsof the methylene bridges in the spacer show that there is a strong influence of the isomerism onthe spin distribution. Importantly, the theoretical calculations of the spin density distributions ofthe radical anions fit well with the experimental EPR results.
|
