Isolation of C60(CF3)n (n=2, 4, 6, 8, 10) with high compositional purity

The high temperature reaction of C-60 with silver(I) trifluoroacetate followed by 500 degreesC sublimation and subsequent HPLC purification has led to the isolation of the five trifluoromethyl[60]fullerenes C-60(CF3)(n) (n = 2, 4, 6, 8, 10). Four of them have >90% compositional purity. Two of the compounds. C-60(CF3)(4) and C-60(CF3)(6), were obtained as C-1-symmetry isomers with >90% isomeric purity, and a sample of C-60(CF3)(2) also contained ca. 15-20% of a C-s-symmetry isomer of C-60(CF3)(4). The new compounds were characterized by IR and EI mass spectrometry (all five compounds), F-19 NMR spectroscopy (C-60(CF3)(2), C-60(CF3)(4), and C-60(CF3)(6)), and 2D COSY F-19 NMR spectroscopy (C-60(CF3)(4) and C-60(CF3)(6)). Calculations at the AM1 and DFT levels of theory have led to the prediction of the most likely structures for C-60(CF3)(2), C-1-C-60(CF3)(4), Cs-C-60(CF3)(4), and the two most likely structures of C-1-C-60(CF3)(6). (C) 2003 Elsevier B.V. All rights reserved.