Pyrolytic Trifluoromethylation of [76]-, [78]-, [84]-, and Aza[60]Fullerenes with Silver Trifluoroacetate; Evidence for Coordination of Fullerenes to Silver

Pyrolytic trifluoromethylation of [76], [78], [84], and aza[60]fullerenes with silver trifluoroacetate at 300°C results in extensive polyaddition of up to 18, 18, 20 and 20 CF₃ groups, respectively. In contrast to trifluoromethylation of [60]- and [70]fullerenes that give a full range of derivatives ranging upwards from C_n(CF₃)₂, [76]-, [78]-, and [84]-fullerenes only give C_n(CF₃)_6-18 derivatives, largely in the 10-12 CF₃ range; reaction with [76]fullerene is accompanied by formation of C₆₀(CF₃)₆ attributed to cage fragmentation. For aza[60]fullerene the hexa-addition level dominates, in contrast to its other reactions which give predominantly penta-addition products. All the compounds showed peaks at 1256±2 and 1180-1190 cm^-1, due to the CF₃ group, and peaks in this region are shown also by the soluble extract obtained on trifluoromethylation of nanotubes. As in trifluoromethylation of [60]- and [70]-fullerenes, the products obtained initially are involatile, attributed to formation os silver complexes; these are decomposed on subsequent solution in toluene. Mixed isomeric trifluoromethylated C₆₀F₈ derivatives viz. C₆₀F₇CF₃, C₆₀F₆(FG₃)₂, C₆₀F₅(CF₃)₃ and C₆₀F₄(CF₃)₄, and C₆₀F₄CF₃CF₂CF₃ (a C₆₀F₆ derivative) have been isolated from fluorination of [60]fullerene with MnF₃/K₂NilF₆ at 510°C.