Synthesis
and Structure of an Open-Cage Thiafullerene
C<sub>69</sub>S: Reactivity Differences of an Open-Cage C<sub>70</sub> Tetraketone Relative to Its C<sub>60</sub> Analogue
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Abstract
An
open-cage C<sub>70</sub> fullerene with a 13-membered ring-opening
and a bis(hemiacetal) moiety was synthesized by the reaction of the
corresponding open-cage C<sub>70</sub> diketone with nucleophilic
oxidizing agents. The size of the cage opening could be expanded by
a subsequent dehydration reaction. Reaction of the thus obtained open-cage
C<sub>70</sub> tetraketone with elemental sulfur in the presence of
tetrakis(dimethylamino)ethylene resulted in the formation of the first
example of an open-cage C<sub>69</sub>S thiafullerene with a 12-membered
ring-opening. The formation of this sulfur-containing heterofullerene
reflects a significantly different chemical reactivity for the open-cage
C<sub>70</sub> tetraketone relative to its C<sub>60</sub> analogue.
The structures of all novel compounds were unambiguously determined
by single crystal X-ray diffraction analyses, in addition to which
the electrochemical properties of the thiafullerene C<sub>69</sub>S were examined and compared with those of the corresponding C<sub>70</sub> analogue