The volatile fluorofullerene products of high-temperature reactions of C
60 with the ternary manganese(III, IV) fluorides KMnF
4, KMnF
5, A
2MnF
6 (A
+ = Li
+, K
+, Cs
+), and K
3MnF
6 were monitored as a function of reaction temperature, reaction time, and stoichiometric ratio by
in situ Knudsen-cell mass spectrometry. When combined with fluorofullerene product ratios from larger-scale (bulk) screening reactions with the same reagents, an optimized set of conditions was found that yielded the greatest amount of C
60F
8 (KMnF
4/C
60 mol ratio 28-30, 470 °C, 4-5 h). Two isomers of C
60F
8 were purified by HPLC, one of which has not been previously reported. Quantum chemical calculations at the DFT level combined with 1D and 2D
19F NMR, FTIR, and FT-Raman spectroscopy indicate that the C
60F
8 isomer previously reported to be 1,2,3,8,9,12,15,16-C
60F
8 is actually 1,2,3,6,9,12,15,18-C
60F
8, making it the first high-temperature fluorofullerene with non-contiguous fluorine atoms. The new isomer, which was found to be 1,2,7,8,9,12,13,14-C
60F
8, is predicted to be 5.5 kJ mol
−1 more stable than 1,2,3,6,9,12,15,18-C
60F
8 at the DFT level. In addition, new DFT calculations and spectroscopic data indicate that the compound previously isolated from the high-temperature reaction of C
60 and K
2PtF
6 and reported to be 16-CF
3-1,2,3,8,9,12,15-C
60F
7 is actually 18-CF
3-1,2,3,6,8,12,15-C
60F
7.
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