Singlet Oxygen Involvement in the Photochemical Reaction of C60 and Amines. Synthesis of an Alkyne-Containing Fullerene

Photochemical addition of 3-diethylamino-l-propyne (DEAP) to C60 leads to a novel fullerene adduct (1). The addition of DEAP to C60 did not occur in the expected [2+2] fashion. Instead, addition took place at the methylene carbons alpha to the nitrogen, resulting in the replacement of two C-H bonds with C60-C bonds. This reaction provides a facile route to a fullerene adduct containing an alkyne moiety. Study of the mechanism of addition disclosed the unexpected involvement of singlet oxygen. Other previously reported additions of amines to fullerenes also appear to involve singlet oxygen.