REGIOSELECTIVITY OF MULTIPLE CYCLOPROPANATIONS OF C-60 AND INTRODUCTION OF A GENERAL BOND-LABELING ALGORITHM FOR FULLERENES AND THEIR DERIVATIVES

A computational (AM1) analysis is presented which shows that the obser ved regioselectivities of multiple cyclopropanations of C-60 are due t o orbital-allowed processes. Next to the coefficients of frontier orbi tals the characteristic cage distortions of the oligomethanofullerenes are discussed. For further experimental corroboration the synthesis a nd characterization of an unsymmetrical trisadduct with a I,eI,III-ad dition pattern are described. Moreover, since a systematic and descrip tive assignment of addition patterns in derivatives of C-60 and higher fullerenes becomes more and more important, a simple and general algo rithm is introduced, which enables unambiguous bond labeling of both [ 6,6]- and [5,6]-bonds as well as the assignment of the absolute config uration of any fullerene derivative.