With one exception, isolable C 70 X 10 derivatives, which include C 70 H 10 , [1] C 70 Me 10 , [2] C 70 Ph 10 , [3] C 70 Ph 9 (OH), [4] C 70 Ph 8 (OH) 2 , [4] C 70 Cl 10 , [5] and C 70 Br 10 , [6] have the "equatorial-belt" C s structure shown in Figure 1, with the ten substituents [7] positioned on a closed loop of ten edge-sharing hexagons, nine of which are para-C 6 X 2 fragments and one of which is an ortho-C 6 X 2 fragment (p 9 o(loop)). [8][9][10] The exception is the recently described compound C 70 (tBuOO) 10 , which has the C 2 structure also shown in Figure 1 with an all-para ribbon of nine edge-sharing C 6 (tBuOO) 2 hexagons (p 9 ), presumably because the tBuOO groups are too large to be on adjacent cage C atoms. [11] We recently reported the synthesis of batches (more than 10 mg) of a single isomer of C 70 (CF 3 ) 10 at 470 8C in 27% overall yield based on converted C 70 . [12] A combination of 1Dand 2D-COSY 19 F NMR spectroscopy showed that this derivative has C 1 symmetry and, by analogy with the structure of a spectroscopically similar C 1 isomer of C 60 (CF 3 ) 10 , most probably has its ten CF 3 groups arranged in the form of a ribbon of nine meta-C 6 (CF 3 ) 2 and/or para-C 6 (CF 3 ) 2 edgesharing hexagons. [12] We now report an X-ray diffraction study of this high-yield, high-temperature C 1 -C 70 (CF 3 ) 10 isomer, which demonstrates that the ribbon of hexagons is the