Direct benzyne-C60 addition does not generate a [5,6] open fulleroid

Recent reports describe the different products resulting from the reaction of C₆₀ with benzyne generated from anthranilic acid derivatives and isoamyl nitrate in the presence and absence of triethylamine. Reinvestigation here via ¹H, ¹³C, HMBC NMR and Mass spectroscopy elucidates that these products are the 6,6] closed C₆₀-fused δ lactones, and not the 5,6] open fulleroids which would result from benzyne addition. Furthermore, theoretical calculations show that the open isomer 5,6] benzyne addition is less stable than the 5,6] closed isomer as an isolable product.