Diederich F, Whetten R L, Thilgen C, Ettl R, Chao I, Alvarez M M
Science. 1991 Dec 20;254(5039):1768-70. doi: 10.1126/science.254.5039.1768.
Early reports on the formation of the higher fullerenes C(76), C(78), C(84), C(90), and C(94) by resistive heating of graphite stimulated theoretical calculations of possible cage structures for these all-carbon molecules. Among the five fullerene structures with isolated pentagons found for C(78), a closed-shell D3h-isomer was predicted to form preferentially. Two distinct C(78)-isomers were formed in a ratio of approximately 5:1 and could be separated by high-performance liquid chromatography. The carbon-13 nuclear magnetic resonance (NMR) spectrum of the major isomer is uniquely consistent with a C2v-structure. The NMR data also support a chiral D(3)-structure for the minor isomer. The isolation of specifically these two isomers of C(78) provides insight into the stability of higher fullerene structures and into the mechanism for fullerene formation in general.
早期关于通过石墨电阻加热形成更高富勒烯C(76)、C(78)、C(84)、C(90)和C(94)的报道激发了对这些全碳分子可能的笼状结构的理论计算。在为C(78)找到的具有孤立五边形的五种富勒烯结构中，预测优先形成闭壳D3h异构体。两种不同的C(78)异构体以大约5:1的比例形成，并且可以通过高效液相色谱法分离。主要异构体的碳-13核磁共振（NMR）光谱与C2v结构唯一一致。NMR数据也支持次要异构体的手性D(3)结构。专门分离出这两种C(78)异构体，有助于深入了解更高富勒烯结构的稳定性以及一般富勒烯形成的机制。
