ELSEVIER
Synthetic Metals 103 (1999) 2368
Tetrathiaf~llvalene-C6o based dyads by Diels-Alder reaction of bis(methyIene)[ZPI]T’I’F and CGO D. Kreher,”
S. G. Liu,” C. J3oulle, ab &l. Carlou?
I’. Ih~dhon-imc,~
A, Gorgucs,“*M.
MasC C,Rovira,%nd
J, Vcciana,C
a IngBnieric MolCcuiaire et MatCriaux Organiqucs, Uuivl Angers-CNRS , 2 Boulevard Lavoisicr, 4W5 Angers, France b Laboratoire de Synthese Organique, Univ. Nantes-CNRS, 2 rue de la HoussinEre, 4322 Names, France c Institnt de Cibncia de hlaterials de l3arcclona (CSIC) Campus de la UAB, 08193 Bellatcrra, Barcelona, Spain
Abstract
Monoadducts of tetrathlafuIvalenc (TTF) with Cm arc synthesized by [&2] Diels-Alder cycloaddition using correspondiig 2,3&is(methylene)dihydroTTF 1. These cycloadducts 2 are spectroscopically characterized and clectrochemicaily studied. Keywords: Heterocycle synthesis, TetrarilicrJFulvalenes, Ek~trochucal
Since their discovery, and more recentip since the development of tcchniqucs for their large scale preparation, f’ullerenes have attracted considerable interest ol’scientists. In particular, the very exciting electronic properties of COO doped forrrs have atvakened considerable interest in studying the electron transfer between ;c-donors, including TTF derivatives, and Cm. One recent trend currently developed consists in the covalent linking of the electron donor fragment to the fullercne core [l]. In order to better promote a spontaneous eicctron transfer between such antagonistic redox counterparts and to take advantage of the vicinity factors, wz have devclopcd a new family of TTF-[60] fullerene dyads in which the TTF core is directly attached by two u bonds to COO. Our strategy involves the [4+2] Diels-Alder cycloaddition of C&O to 2,Xbis(methylene)2,3-dihydroTTFs 1. According to the methodology developed by K. h4lilIen 121, these transient dienes were generated in situ by iodine-induced 1 ,4-reductive 13rZelimination from 2,3-bis(bromomethyl)TTFs 131.
1
2~ R,R=-SM, Zb R.R= -S[CH2M33> zc R-K = -scHp,s
Structures of monoadducts 2 previously supported by spectroscopic and electrochemical data [3] (see table) are also confirmed by ERR-electrochemical studies which will bc detailed. Thus, upon electrooxidation of 2a, b, e one observes the arising of an EPR signal related to (2)‘. (g-2.007) as a triplet resulting from the coupling of the single electron on tic TTF core with two axial protons of both mothylene bridges (~11.1 = 1.45, 1.45 and 1.39 G respectively). The 33S hyperfine coupling constant is also observed (as = 3.96,4.00 and 3.80 G respectively).
methods, Fzliielanes
and derivatives
Additionally, upon electroreduction, 2a, b and c afford a singlet (g = 1.9%X2, 1.9’W’PY~and I-.?!%65 respectively) related to the anion radical. Such results are currently cxtcnded to the synthesis of dnmbbeli 3 triad from the unprecedented retrnkis (methylene)tetrahydroTTF.
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0319-677919918 - see front matter 0 1999 Elsevier Science S.A. Ail rights reserved. PII: SO379-6779(98)00710-3