Synthesis and properties of bingel-type methanofullerene - π-extended-TTF diads and triads

Article abstract of DOI:10.1021/jo020412l

Novel C₆₀/π-extended tetrathiafulvalene (exTTF) diads (12a-c) and triads [D₂A (14a-c) and DA₂ (25, 27a-c)] have been synthesized by the Bingel cyclopropanation reaction of the respective exTTF-containing malonates and [60]fullerene. The reaction of exTTF-bismalonates with C₆₀ affords the respective C₆₀-exTTF diads (26a-c) together with the triad C₆₀-exTTF-C₆₀ (25, 27a-c) and a regioisomeric mixture of bisadducts (28b-c). Theoretical calculations (PM3) predict the favored geometry for triads 14a-c depending upon the orientation (up and down) of the 1,3-dithiole rings in the exTTFs, as well as the more stable regioisomers for the bisadducts 28. Cyclic voltammetry measurements reveal that C₆₀ and exTTF units do not intereact in the ground state. Compounds 26a-c and 27a-c are not electrochemically stable. A photoinduced electron transfer leading to the formation of the radical pair (C₆₀^--exTTF^?+) has been observed for compounds 14a-c.