Some 4-fluorophenyl derivatives of [60]fullerene;: spontaneous oxidation and oxide-induced fragmentation to C58

The main products from the reaction of C60Cl6 with fluorobenzene-FeCl3 are C-60(4-FC6H4)(5)Cl, 1,4-(4-FC6H4)(2)C-60 (both of C-s symmetry) and asymmetric C-60(4-FC6H4)(4), accompanied by a small amount of C-60(4-FC6H4)(4)H-2. Exposure of the product to light and air before processing gives other components, including C-60(4-FC6H4)(4)(4-FC6H3)O-2, C-60(4-FC6H4)(5)OH, and C-60(4-FC6H4)(6) (each of C-s symmetry), C-60(4-FC6H4)(4)O-2, C-60(4-FC6H4)(6)O-2, C-60(4-FC6H4)(7)H, and C-60(4-FC6H4)(5)H(OH)(2)/C-60(4-FC6H4)(5)H. The formation of the oxides from air-exposed reaction products emphasises the need for atmospheric protection of fullerene derivatives. Fragmentation of the oxides during EI mass spectrometry occurs readily to give C-58 and derivatives which must contain adjacent pentagons, stabilisation being derived from the presence of a heptagon.