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

Abstract

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.

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Keywords:

• Trifluoromethylation
• silver complexes
• higher fullerenes
• nanotubes

Acknowledgment

We thank Professor A. Hirsch for a sample of aza[60]fullerene.

Notes

*Deceased