Аннотация:Novel difluoromethylenated
[70]fullerene derivatives, C70(CF2)n, n=1–3,
were obtained by the reaction of C70 with
sodium difluorochloroacetate. Two major
products, isomeric C70(CF2) monoadducts
with [6,6]-open and [6,6]-closed
configurations, were isolated and their
homofullerene and methanofullerene
structures were reliably determined using a
variety of methods including X-ray analysis
and high-level spectroscopic techniques.
The [6,6]-open C70(CF2) constitutes the first
homofullerene example of a non-hetero
[70]fullerene derivative in which
functionalization involves the most reactive
bond in the polar region of the cage.
Voltammetric estimation of the EA of the
C70(CF2) isomers showed that it is
substantially higher for the [6,6]-open
isomer (since the 70π-conjugated system is
retained) as compared to that of the [6,6]-
closed form, the latter being similar to the
EA of pristine C70.
In situ ESR spectroelectrochemical
investigation of the C70(CF2) radical anions
along with DFT calculations of the
hyperfine coupling constants evidence the
first example of an interconversion 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 C70(CF2) constitutes an
interesting example of a redox switchable
fullerene derivative.