化学英语在线翻译 请帮帮忙Figure 1. ORTEP drawing of 7 at the 50% probabi
化学英语在线翻译 请帮帮忙
Figure 1. ORTEP drawing of 7 at the 50% probability level. C13C9 1.332(7), C23C3 1.468(7), C23C8 1.322(8), S23C8 1.705(6),
S33C10 1.747(5), C103C13 1.337(8) A, . The torsion angle between the pyridine and the dithiole rings is 25.9°.
problems owing to undesired donor–acceptor interactions
either at stages preceding the chemical linking or
during isolation of the final product.2
One of the strongest acceptors used for linking with the
TTF moiety, by a unique approach, is the N-alkyl
pyridinium cation in a TTF-sigma spacer-Py+ system.3
Derivatives involving both TTF and Py+ moieties are
excellent models for studying ICT versus ET processes
since the formation of the strong accepting moiety
occurs on the very last stage of the synthesis, and under
mild and controllable conditions.
Recently a TTF-p-spacer-Py+ system with an ethenyl p
spacer was prepared.4 In the present communication we
report a simple synthetic route for the synthesis of a
D–A system in which the TTF moiety is directly linked
to the pyridinium cation moiety, without any spacer,
according to Scheme 1. Attempts to apply the known
procedure described for the synthesis of aryl substituted
1,3-dithiole-2-thiones from the corresponding 1,3-dithiole-
2-(N-diethyl)immonium salt5 for the key precursor,
4-(4%-pyridyl)-1,3-dithiole-2-thione 5, have been unsuccessful.
However, the cyclization of 3 in concentrated
sulfuric acid afforded 1,3-dithiole-2-one derivative 4 in
70% yield. Derivative 5 can be obtained in 65–70%
yields upon treatment with phosphorus sulfide. Although
the coupling between 5 and 4,5-dimethylthio-
1,3-dithiole-2-thione6 with triethyl phosphite gives the
unsymmetrical TTF derivative 7 in low yields along
with symmetrical derivatives, chromatographic separation
is simple due to the large difference in Rf of the
products. Long chain substituted alkylthio substituted
derivatives can also be easily prepared according to the
above protocol (for instance, the 2,3-dihexadecylthio
derivative of 7 in 12% yield).