X- and W-band ESR study on gamma-cyclodextrin bicapped C-60 after NH3-gas doping

Among the diverse topics of supramolecular chemistry of gamma -cyclodextrin (gamma -CyD) bicapped C-60 systems, electronic and magnetic properties ind uced by electron dopants have not been well elucidated yet. This paper desc ribes the crystalline solid sample of C-60(gamma -CyD)(2). 24H(2)O treated by NH3-gas doping. Several open-shell species including an anionic C-60 hav e been detected and characterized by conventional cw-ESR spectroscopy. It h as turned out that the monoanionic C-60 is extremely stable at room tempera ture for more than several months and it undergoes a symmetry reduction by the Jahn-Teller distortion to have an axial symmetry. W-band ESR spectrosco py has been invoked to resolve the g-anisotropy. In addition, the character istic features appearing in the FV-band spectra has been explained by the p ossible occurrence of the dynamic behavior underlain by quantum tunneling b etween the distorted forms of NH3 radical cation due to the dynamic pseudo Jahn-Teller effect.