Arylation of [60]fullerene via electrophilic aromatic substitution involving the electrophile C60Cl6: Frontside nucleophilic substitution of fullerenes

Reaction of C60Cl6 and ferric chloride with aromatic compounds gives the corresponding C-6-symmetric aryl derivatives C60Ar5Cl, where Ar = phenyl, tolyl, anisyl, tert-butylphenyl, fluorophenyl, trimethylsilylphenyl and thienyl. The derivatives arising from exclusive para substitution in anisole and fluorobenzene, together with C-60(4-FC6H4)(5)H have been isolated and fully characterised. Toluene undergoes substitution in the ortho as well as the para position. Traces of octaaryl derivatives are obtained in the reaction with. toluene and anisole. The steric bulk of the chlorofullerene (the largest electrophile known)accounts for the failure to achieve substitution in mesitylene and the abnormal deprotonation rather than desilylation In the reaction with trimethylsilylbenzene. Protiodesilylation of the trimethylsilylphenyl derivative was achieved by reaction with acid, With triphenylphosphine, C60Ar5Cl compounds react to give C60Ar5H and with toluene/FeCl3, C60Ph5Cl gives C(60)Ph(5)tolyl. C-60(4-FC6H4)(5)H showed a marked tendency to acquire oxygen, suggesting that this oxygenation is facilitated by electron withdrawal, FAB mass spectrometry of C-60(4-FC6H4)(5)H, C60Ph5Cl, C60Ph5H and also of C70Ph10 shows addition of up to 9C(2) fragments in each case; this parallels two previous reports of C-2 addition during FAB mass spectrometry, The replacement of chlorine by aryl groups at the same site indicates that frontside nucleophilic substitution on the cage must occur, involving a cationic fullerene intermediate.