Electron Delocalization and Dimerization in Solid C_(59)N Doped C_(60) Fullerene

摘要

Electron spin resonance and ab initio electronic structure calculations show an intricate relation between molecular rotation and chemical bonding in the dilute solid solution. The unpaired electron of C_(59)N is delocalized over several C_(60) molecules above 700 K, while at lower temperatures it remains localized within short range. The data suggest that below 350 K rigid C_(59)N-C_(60) heterodimers are formed in thermodynamic equilibrium with dissociated rotating molecules. The structural fluctuations between heterodimers and dissociated molecules are accompanied by simultaneous electron spin transfer between C_(60) and C_(59)N molecules. The calculation confirms that in the C_(59)N-C_(60) heterodimer the spin density resides mostly on the C_(60) moiety, while it is almost entirely on C_(59)N in the dissociated case.