Oligothiophenes III
1185
temperature with stirring. After 6 h, the mixture was cooled to 08C and pyridine
(2.5 ml) and I (1.55 g, 5.6 mmol) in THF (30 ml) were added. The reaction
mixture was allowed to reach room temperature. Finally, the reaction mixture
was refluxed for 72 h. After cooling, CH2Cl2 (250 ml) was added, and the
mixture was washed with 0.1 M HCl. The organic layer was dried (MgSO4)
and filtered, and the solvent was evaporated, affording the crude reaction
product, which was chromatographed on silica gel with chloroform–hexane
(10:1). The product was crystallized to give a yellow solid (1.37 g, 95%), mp
207–2088C (toluene). dH (300 MHz, CD2Cl2) 6.67 (d, J 3.99, 2H), 6.95–7.00
(m, 4H), 7.05–7.08 (m, 6H), 7.22 (dd, J1 1.11, J2 5.13, 2H), 7.46 (dd, J1 1.96,
J2 4.42, 2H). dC (75 MHz, CD2Cl2) 125.057, 125.073, 127.796, 127.805,
128.165, 128.253, 128.274, 128.352, 130.582, 130.690, 131.357, 143.200,
143.427. M/z: 520 (100), 260 (10). High-resolution MS: 519.956961; calculated
for C26H16S6: 519.957631. UV (CCl4), log e (lmax): 4.34 (230), 4.38 (330), 4.41
(424). Crystal data for C26H16S6: Monoclinic, space group P21/a; a ¼ 12.302(3)
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A, b ¼ 7.2878(15) A, c ¼ 14.012(4) A, b ¼ 115.26(2)8, V ¼ 1136.1(5)
3
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A , T ¼ 120(1) K, l(Cu Ka) ¼ 1.54178 A, Z ¼ 2. Yellow prism,
0.26 ꢀ 0.16 ꢀ 0.13 mm. Data were collected with Siemens P4 diffractometer.
Ni-filtered Cu(Ka) radiation from a rotating anode. Empirical absorption correc-
tion was done with Xabs2.[8] Solution was created with SHELXS96[9] and
Fourier techinques. Full-matrix refinement with SHELX197[10] gave R ¼ 0.0582
for 1331 reflections with Io . 2s(Io), of 1502 independent.
(E)-1,2-Di(2,20-bithiophen-5-yl)-1,2-diphenylethene (V)
From II (1.55 g, 5.6 mmol) in THF (30 ml), following the procedure given pre-
viously for the synthesis of IV, the title compound was prepared as a yellow solid
(1.32 g, 93%), mp 193–1948C (toluene). dH (300 MHz, CD2Cl2) 7.44–7.47
(m, 10H), 7.15–7.17 (m, 2H), 6.80–6.94 (m, 4H), 6.80 (d, J 3.91, 2H), 6.25
(d, J 3.91, 2H). dC (75 MHz, CD2Cl2) 145.257, 142.004, 138.613, 137.574,
133.423, 131.373, 131.052, 129.448, 128.717, 128.160, 124.789, 123.737,
122.969. M/z: 508 (100), 254 (10). High-resolution MS: 508.042788; calculated
for C30H20S4: 508.044788. UV (CCl4), log e (lmax): 4.35 (229), 4.35 (332), 4.39
(406). Crystal data for C30H20S4: Monoclinic, space group P21/a; a ¼ 7.604(2)
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A, b ¼ 11.103 (3) A, c ¼ 13.952(3) A, b ¼ 95.25(2)8. V ¼ 1173.10(5)
3
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A , T ¼ 90(1) K, l(Mo Ka) ¼ 0.71073 A, Z ¼ 2. Yellow needle,
0.37 ꢀ 0.16 ꢀ 0.12 mm. Data collected with Siemens (Bruker) SMART
CCD diffractometer. Solution and refinement were done as for (IV) which
gave R ¼ 0.041 for 2826 reflections with Io . 2s(Io), of 3645 independent.
1,1,2,2-Tetra(2,20-bithiophen-5-yl)ethene (VI)
From III (2.0 g, 5.6 mmol) in THF (30 ml), following the procedure given
previously for the synthesis of IV and V, the title compound was prepared