Center for Polymers and Organic Solids, Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States.
J Am Chem Soc. 2011 Aug 17;133(32):12410-3. doi: 10.1021/ja204974m. Epub 2011 Jul 22.
The reaction between a bulky N-heterocylic carbene (NHC) and C(60) leads to the formation of a thermally stable zwitterionic Lewis acid-base adduct that is connected via a C-C single bond. Low-energy absorption bands with weak oscillator strengths similar to those of n-doped fullerenes were observed for the product, consistent with a net transfer of electron density to the C(60) core. Corroborating information was obtained using UV photoelectron spectroscopy, which revealed that the adduct has an ionization potential ∼1.5 eV lower than that of C(60). Density functional theory calculations showed that the C-C bond is polarized, with a total charge of +0.84e located on the NHC framework and -0.84e delocalized on the C(60) cage. The combination of reactivity, characterization, and theoretical studies demonstrates that fullerenes can behave as Lewis acids that react with C-based Lewis bases and that the overall process describes n-doping via C-C bond formation.
大位阻 N-杂环卡宾（NHC）与 C(60)之间的反应生成了一种热稳定的两性离子路易斯酸碱加合物，该加合物通过 C-C 单键连接。产物的低能量吸收带具有与 n 掺杂富勒烯相似的弱振子强度，表明电子密度向 C(60)核发生了净转移。使用紫外光电子能谱获得了佐证信息，表明加合物的电离势比 C(60)低约 1.5 eV。密度泛函理论计算表明，C-C 键具有极性，总电荷为+0.84e 位于 NHC 框架上，-0.84e 离域在 C(60)笼上。反应性、表征和理论研究的结合表明，富勒烯可以作为路易斯酸与基于 C 的路易斯碱反应，整个过程描述了通过 C-C 键形成的 n 掺杂。
