[6,6]-Open and [6,6]-Closed Isomers of C-70(CF2): Synthesis, Electrochemical and Quantum Chemical Investigation

作者：Samoylova Nataliya A; Belov Nikita M; Brotsman Victor A; Ioffe Ilya N; Lukonina Natalia S; Markov Vitaliy Yu; Ruff Adrian; Rybalchenko Alexey V; Schuler Paul; Semivrazhskaya Olesya O; Speiser Bernd; Troyanov Sergey I; Magdesieva Tatiana V^*; Goryunkov Alexey A

来源：Chemistry - A European Journal, 2013, 19(52): 17969-17979.

DOI：10.1002/chem.201302946

• density functional calculations
• fullerenes
• molecular switches
• spectroelectrochemistry
• structure elucidation

Novel difluoromethylenated [70]fullerene derivatives, C-70(CF2)(n) (n=1-3), were obtained by the reaction of C-70 with sodium difluorochloroacetate. Two major products, isomeric C-70(CF2) mono-adducts with [6,6]-open and [6,6]-closed configurations, were isolated and their homofullerene and methanofullerene structures were reliably determined by a variety of methods that included X-ray analysis and high-level spectroscopic techniques. The [6,6]-open isomer of C-70(CF2) constitutes the first homofullerene example of a non-hetero [70]fullerene derivative in which functionalisation involves the most reactive bond in the polar region of the cage. Voltammetric estimation of the electron affinity of the C-70(CF2) isomers showed that it is substantially higher for the [6,6]-open isomer (the 70-electron -conjugated system is retained) than the [6,6]-closed form, the latter being similar to the electron affinity of pristine C-70. In situ ESR spectroelectrochemical investigation of the C-70(CF2) radical anions and DFT calculations of the hyperfine coupling constants provide evidence for the first example of an inter-conversion between the [6,6]-closed and [6,6]-open forms of a cage-modified fullerene driven by an electrochemical one-electron transfer. Thus, [6,6]-closed C-70(CF2) constitutes an interesting example of a redox-switchable fullerene derivative.

• 出版日期2013-12-23