RESILIENCE OF THE FULLERENE CAGE - ANALYSIS OF DISTORTIONS IN COMPUTED STRUCTURES OF FULLERENE DERIVATIVES

The extent of cage distortion in a number of structures of fullerene d erivatives, C60H60-6n (n = 0-8), optimized using the MNDO procedure is evaluated. Isomers containing isolated benzenoid rings distributed ov er the fullerene framework with the highest possible symmetry have bee n considered. For C60H24, C60H36 and C60H48, T-h symmetry structures w ith localized double bonds also have been analyzed. The fullerene cage is indicated to withstand severe distortions following derivatization , with all calculated structures being true minima with a Hessian of z ero. Particularly large deviation of the carbon framework from the sph eroidal shape is found in C60H30, C60H36 and C60H42, which are nonethe less computed to be relatively stable. Cage distortions have been quan tified in terms of moments of inertia values. For a given hydride, the isomer with the lower average moment of inertia is more stable. Furth er, along the series C-60 to C60H60, successive hydrogenation is energ etically favorable when the increase in cage moment of inertia is smal ler.