Addition of Carbene to the Equator of C_(70) To Produce the Most Stable C_(71)H2 Isomer: 2aH-2(12)a-Homo(C_(70)-D_(5h)(6))5,6fullerene

摘要

Unlike C_(60), in which all carbon-atom environments are identical, C_(70) has five distinct carbon-atom environments, which give rise to eight distinct C-C bond types. Hence, the addition chemistry of C_(70) involves both chemo- and regiose-lectivity. The synthetic chemistry of C_(70) is centered on the areas near the poles, as these areas have the highest curvature and hence high bond strain. This relatively high bond strain in turn makes the polar regions the most reactive sites of the molecule. The equatorial region of C_(70), on the other hand, has little curvature and hence lower bond strain. Thus, the carbon atoms at the equator are much less reactive, as there is a much higher activation barrier to be overcome before reactions can occur. For example, carbene (CH2) has been added to the polar region of C_(70), and several isomers of C_(71)H2 have been synthesized and fully characterized. However, the addition of carbene to the equatorial bond of C_(70) (to form C_(2v)-C_(71)H2) has not been detected.