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Acta Crystallogr Sect E Struct Rep Online. 2008 May 1; 64(Pt 5): o938.
Published online 2008 April 30. doi:  10.1107/S1600536808011653
PMCID: PMC2961168

1,2-Bis[5-(4-cyano­phen­yl)-2-methyl-3-thien­yl]-3,3,4,4,5,5-hexa­fluoro­cyclo­pent-1-ene: a photochromic diaryl­ethene compound

Abstract

The mol­ecules of the title compound, C29H16F6N2S2, a photochromic dithienylethene with 4-cyano­phenyl substituents, adopt an anti­parallel arrangement that is reponsible for photoactivity. The mol­ecule lies on a twofold rotation axis. The dihedral angle between the nearly planar cyclo­pentenyl and heteroaryl rings is 142.5 (3)°, and that between the heteroaryl and benzene rings is 22.4 (3)°. The distance between the heteroaryl rings of adjacent mol­ecules is 3.601 (2) Å, indicating a π–π interaction.

Related literature

For a review of dithienylethyl­enes as photochromic compounds, see: Irie (2000 [triangle]). For phenyl-substituted derivatives, see: Pu, Liu et al. (2005 [triangle]); Pu, Yang et al. (2005 [triangle]). For another similar structure, see: Kobatake et al. (2004 [triangle]). For the manifestation of possible photochromic activity in relation to the conformation, see: Woodward & Hoffmann (1970 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-0o938-scheme1.jpg

Experimental

Crystal data

  • C29H16F6N2S2
  • M r = 570.56
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o938-efi1.jpg
  • a = 24.987 (10) Å
  • b = 9.276 (4) Å
  • c = 10.774 (4) Å
  • β = 95.911 (7)°
  • V = 2483.8 (17) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.28 mm−1
  • T = 113 (2) K
  • 0.36 × 0.20 × 0.10 mm

Data collection

  • Rigaku Saturn diffractometer
  • Absorption correction: multi-scan (Jacobson, 1998 [triangle]) T min = 0.905, T max = 0.972
  • 9917 measured reflections
  • 2437 independent reflections
  • 2130 reflections with I > 2σ(I)
  • R int = 0.032

Refinement

  • R[F 2 > 2σ(F 2)] = 0.057
  • wR(F 2) = 0.145
  • S = 1.06
  • 2437 reflections
  • 180 parameters
  • H-atom parameters constrained
  • Δρmax = 0.90 e Å−3
  • Δρmin = −0.65 e Å−3

Data collection: CrystalClear (Rigaku/MSC, 2001 [triangle]); cell refinement: CrystalClear; data reduction: CrystalStructure (Rigaku/MSC, 2004 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808011653/ng2448sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808011653/ng2448Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

This work was partially supported by the Natural Science Foundation of Jiangxi, China (grant No. 0620012), the Science Funds of the Education Office of Jiangxi, China (grant No. [2007] 279) and the Research Fund of Jiangxi Science and Technology Normal University.

supplementary crystallographic information

Comment

Dithienylethenes are the most promising organic photochromic compounds for photoelectronic devices(Irie, 2000).Dithienylethenes bearing terminal phenyl groups are of special interest, because phenyl group can be substituted by many electron-donating or electron-withdrawing groups that influence the properties(Pu, Yang,Xu et al.,2005). In order to investigate the substituent effect at the para-position on the photochemical properties, we have now synthesized the title compound, (Ia), and its structure is presented in this paper.

To the best of our knowledge,this is the first symmetrical dithienylethene compound with phenyl groups bearing para substituent. The molecular structure of (Ia) is shown in Fig. 1 and selected geometric parameters are given in Table 1.

The molecule contains two thiophene rings substituted by two para-cyanophenyl rings in a photoactive antiparallel conformation. In the cyclopent-1-ene ring, the C12=C12A bond is clearly a double bond, and the other bonds in the ring are clearly single bonds(see Table 1). The two thiophene rings are linked by the C12=C12A double bond.The two methyl groups are located on different sides of the double bond and are thus trans with respect to the double bond. Such a configuration is crucial for the compound to exhibit photochromic and photoinduced properties (Woodward & Hoffmann, 1970). The dihedral angles between the least-squares plane of the atoms of the central cyclopent-1-ene ring and the adjacent thiophene rings are 142.5 (3)°, and those between thiophene rings and the adjacent benzene rings are both 22.4 (3)°.The distance between the two reactive C atoms (C4_C4A) is 3.601 (2) Å. This distance indicates that the crystal can undergo photochromism in the crystalline phase because the photochromic reactivity of crystals depends on the distance between the reactive C atoms being less than 4.2 Å(Kobatake et al., 2004).

Upon irradiation with 313 nm light, colorless single crystals of (Ia) turned to blue rapidly, and the blue color remained stable in the dark. When the blue crystals were dissolved in hexane, the solution also remained blue.The absorption maximum of this solution is observed at a wavelength of 596 nm, consistent with the presence of the closed-ring isomer, (Ib).This result suggests that the title compound undergoes a photochromic reaction to produce the closed-ring molecule of (Ib) in the single-crystal phase. We have not, so far, been able to determine the crystal structure of (Ib). Furthermore, upon irradiation with wavelengths longer than 450 nm, the blue crystal changes back to colorless, and the absorption spectrum of a hexane solution of the colorless crystals is the same as that of a solution of the open-ring form, (Ia), with the absorption maximum at 314 nm.

Experimental

The title compound was originally derived from 2-methylthiophene(1). 3-Bromo-2-methyl-5-(4-cyanophenyl)thiophene, (4) (4.60 g, 16.5 mmol), in 78.8% yield was synthesized by reacting(3) (4.62 g, 20.9 mmol) (Pu, Liu et al., 2005) with 4-cyano-brombenzene (3.82 g, 21.0 mmol) in the presence of Pd(PPh3)4 (0.5 g) and Na2CO3 (2 mol/L, 30 ml) in tetrahydrofuran (THF, 80 ml) for 16 h at 343 K. To a stirred THF solution (60 ml) of (4) (2.21 g, 7.96 mmol) 3.3 ml of n-BuLi/hexane solution (2.5 M, 8.2 mmol) was slowly added at 195 K under a nitrogen atmosphere. 30 min later, octa-fluorocyclopentene (0.54 ml, 4.0 mmol) was added and the mixture was stirred for 2 h. The reaction mixture was extracted with diethyl ether and evaporated in vacuo, then purified by column chromatography (petroleum ether) to give the title compound (1.21 g, 2.12 mmol) in 53.3% yield. The compound crystallized from hexane at room temperature and produced single crystals suitable for X-ray analysis. The structure of (Ia) was confirmed by melting point, IR and NMR. Analysis calculated for C29H16F6N2S2, m.p.: 485.7 k 1H NMR (400 MHz, CDCl3) δ 2.03 (s, 6H),δ 7.41 (s, 2H), δ 7.64, 7.70 (d, 8H, J = 8.0 Hz); 13C NMR (400 MHz, CDCl3) δ 14.67, 111.33, 118.47, 124.41, 125.87, 126.28, 132.86, 137.34, 140.20, 143.42; IR (n, KBr, cm-1): 743, 831, 846, 887, 987, 1054, 1108, 1184, 1267, 1309, 1338, 1385, 1413, 1438, 1438, 1508, 1551, 1603, 1633, 2223.

Refinement

H atoms were positioned theoretically and allowed to ride on their parent atoms in the final refinement[C—H = 0.93–0.96Å and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C)].The methyl groups were treated as rigid groups and allowed to rotate about the C—C bond.

Figures

Fig. 1.
The molecular structure of (Ia) with 35% probability ellipsoids, showing the atomic numbering scheme.
Fig. 2.
Interconversion of compound (Ia) and compound (Ib).
Fig. 3.
Synthetical method of compound (Ia).

Crystal data

C29H16F6N2S2F000 = 1160
Mr = 570.56Dx = 1.526 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71070 Å
Hall symbol: -C2ycCell parameters from 3563 reflections
a = 24.987 (10) Åθ = 1.6–27.9º
b = 9.276 (4) ŵ = 0.28 mm1
c = 10.774 (4) ÅT = 113 (2) K
β = 95.911 (7)ºBlock, colorless
V = 2483.8 (17) Å30.36 × 0.20 × 0.10 mm
Z = 4

Data collection

Rigaku Saturn diffractometer2437 independent reflections
Radiation source: rotating anode2130 reflections with I > 2σ(I)
Monochromator: confocalRint = 0.032
Detector resolution: 7.31 pixels mm-1θmax = 26.0º
T = 113(2) Kθmin = 1.6º
ω scansh = −30→30
Absorption correction: multi-scan(Jacobson, 1998)k = −11→11
Tmin = 0.905, Tmax = 0.972l = −12→13
9917 measured reflections

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.057  w = 1/[σ2(Fo2) + (0.0692P)2 + 6.3864P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.145(Δ/σ)max = 0.001
S = 1.07Δρmax = 0.90 e Å3
2437 reflectionsΔρmin = −0.65 e Å3
180 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0031 (9)
Secondary atom site location: difference Fourier map

Special details

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
S10.12440 (3)0.06080 (7)0.81522 (6)0.0293 (2)
F10.04313 (8)0.57014 (18)0.94258 (16)0.0469 (5)
F20.09200 (7)0.57943 (19)0.7907 (2)0.0607 (7)
F3−0.02249 (10)0.7331 (3)0.8302 (2)0.0846 (10)
N10.34207 (11)0.1164 (3)1.4057 (3)0.0492 (7)
C10.13504 (10)0.1761 (3)0.9418 (2)0.0252 (6)
C20.09893 (10)0.2871 (3)0.9294 (2)0.0248 (6)
H20.09810.36210.98930.030*
C30.06264 (10)0.2802 (3)0.8183 (2)0.0244 (6)
C40.07183 (10)0.1622 (3)0.7454 (2)0.0270 (6)
C50.17915 (10)0.1560 (3)1.0408 (2)0.0248 (6)
C60.17718 (11)0.2247 (3)1.1548 (2)0.0281 (6)
H60.14620.27911.16930.034*
C70.21958 (11)0.2150 (3)1.2473 (3)0.0308 (6)
H70.21770.26241.32480.037*
C80.26506 (10)0.1355 (3)1.2265 (3)0.0287 (6)
C90.26789 (11)0.0656 (3)1.1132 (3)0.0292 (6)
H90.29900.01181.09880.035*
C100.22495 (11)0.0750 (3)1.0215 (3)0.0286 (6)
H100.22650.02600.94450.034*
C110.30895 (11)0.1252 (3)1.3245 (3)0.0350 (7)
C120.02472 (10)0.3973 (3)0.7823 (2)0.0228 (5)
C130.04203 (10)0.5483 (3)0.8172 (3)0.0274 (6)
C140.00000.6490 (4)0.75000.0306 (8)
C150.04599 (12)0.1178 (3)0.6201 (3)0.0331 (6)
H15A0.07140.06020.57750.040*
H15B0.03580.20390.57040.040*
H15C0.01380.06030.63020.040*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
S10.0312 (4)0.0264 (4)0.0297 (4)0.0058 (3)−0.0006 (3)−0.0016 (3)
F10.0697 (13)0.0316 (9)0.0346 (10)0.0099 (8)−0.0174 (9)−0.0094 (7)
F20.0327 (10)0.0317 (10)0.122 (2)−0.0050 (8)0.0302 (11)0.0038 (11)
F30.0843 (17)0.0847 (17)0.0741 (15)0.0586 (14)−0.0430 (13)−0.0557 (13)
N10.0378 (15)0.0602 (18)0.0466 (16)−0.0076 (13)−0.0110 (12)0.0141 (14)
C10.0246 (12)0.0227 (12)0.0283 (13)0.0003 (10)0.0023 (10)0.0013 (10)
C20.0240 (12)0.0234 (12)0.0269 (13)0.0005 (10)0.0017 (10)0.0004 (10)
C30.0232 (12)0.0235 (13)0.0263 (13)−0.0004 (10)0.0012 (10)0.0023 (10)
C40.0277 (13)0.0263 (13)0.0268 (13)0.0018 (10)0.0012 (10)0.0016 (11)
C50.0233 (12)0.0221 (12)0.0289 (13)−0.0006 (10)0.0016 (10)0.0044 (10)
C60.0272 (13)0.0262 (13)0.0306 (14)0.0038 (10)0.0011 (10)0.0026 (11)
C70.0357 (15)0.0266 (14)0.0292 (14)−0.0003 (11)−0.0012 (11)0.0032 (11)
C80.0260 (13)0.0267 (13)0.0324 (14)−0.0014 (10)−0.0023 (11)0.0096 (11)
C90.0229 (13)0.0280 (14)0.0366 (15)0.0022 (10)0.0022 (11)0.0064 (11)
C100.0282 (13)0.0275 (13)0.0301 (14)0.0022 (10)0.0033 (11)0.0025 (11)
C110.0304 (14)0.0348 (15)0.0393 (16)−0.0022 (12)0.0007 (13)0.0072 (13)
C120.0249 (12)0.0219 (12)0.0216 (12)−0.0018 (10)0.0032 (10)0.0007 (10)
C130.0218 (13)0.0261 (13)0.0342 (14)−0.0021 (10)0.0027 (11)−0.0006 (11)
C140.038 (2)0.0211 (18)0.032 (2)0.000−0.0003 (16)0.000
C150.0375 (15)0.0310 (15)0.0292 (14)0.0076 (12)−0.0038 (12)−0.0051 (12)

Geometric parameters (Å, °)

S1—C41.724 (3)C6—H60.9500
S1—C11.732 (3)C7—C81.392 (4)
F1—C131.363 (3)C7—H70.9500
F2—C131.341 (3)C8—C91.390 (4)
F3—C141.331 (3)C8—C111.446 (4)
N1—C111.144 (4)C9—C101.384 (4)
C1—C21.367 (4)C9—H90.9500
C1—C51.465 (3)C10—H100.9500
C2—C31.427 (4)C12—C12i1.354 (5)
C2—H20.9500C12—C131.502 (3)
C3—C41.380 (4)C13—C141.531 (3)
C3—C121.467 (3)C14—F3i1.331 (3)
C4—C151.493 (4)C14—C13i1.531 (3)
C5—C61.389 (4)C15—H15A0.9800
C5—C101.402 (4)C15—H15B0.9800
C6—C71.380 (4)C15—H15C0.9800
C4—S1—C193.15 (13)C8—C9—H9120.3
C2—C1—C5127.3 (2)C9—C10—C5120.8 (3)
C2—C1—S1110.0 (2)C9—C10—H10119.6
C5—C1—S1122.54 (19)C5—C10—H10119.6
C1—C2—C3113.8 (2)N1—C11—C8177.0 (3)
C1—C2—H2123.1C12i—C12—C3131.76 (14)
C3—C2—H2123.1C12i—C12—C13110.66 (14)
C4—C3—C2112.6 (2)C3—C12—C13117.6 (2)
C4—C3—C12125.3 (2)F2—C13—F1104.8 (2)
C2—C3—C12121.7 (2)F2—C13—C12113.5 (2)
C3—C4—C15130.6 (2)F1—C13—C12111.3 (2)
C3—C4—S1110.39 (19)F2—C13—C14112.1 (2)
C15—C4—S1118.9 (2)F1—C13—C14108.70 (19)
C6—C5—C10118.7 (2)C12—C13—C14106.5 (2)
C6—C5—C1119.6 (2)F3i—C14—F3108.2 (4)
C10—C5—C1121.6 (2)F3i—C14—C13i111.45 (14)
C7—C6—C5120.9 (2)F3—C14—C13i110.49 (15)
C7—C6—H6119.5F3i—C14—C13110.49 (15)
C5—C6—H6119.5F3—C14—C13111.45 (14)
C6—C7—C8119.8 (3)C13i—C14—C13104.8 (3)
C6—C7—H7120.1C4—C15—H15A109.5
C8—C7—H7120.1C4—C15—H15B109.5
C9—C8—C7120.3 (2)H15A—C15—H15B109.5
C9—C8—C11120.5 (2)C4—C15—H15C109.5
C7—C8—C11119.2 (3)H15A—C15—H15C109.5
C10—C9—C8119.4 (2)H15B—C15—H15C109.5
C10—C9—H9120.3
C4—S1—C1—C20.4 (2)C8—C9—C10—C51.1 (4)
C4—S1—C1—C5−176.3 (2)C6—C5—C10—C9−1.2 (4)
C5—C1—C2—C3176.4 (2)C1—C5—C10—C9175.4 (2)
S1—C1—C2—C3−0.1 (3)C4—C3—C12—C12i37.9 (5)
C1—C2—C3—C4−0.3 (3)C2—C3—C12—C12i−149.8 (3)
C1—C2—C3—C12−173.6 (2)C4—C3—C12—C13−140.0 (3)
C2—C3—C4—C15−176.1 (3)C2—C3—C12—C1332.3 (3)
C12—C3—C4—C15−3.2 (5)C12i—C12—C13—F2−131.7 (3)
C2—C3—C4—S10.6 (3)C3—C12—C13—F246.7 (3)
C12—C3—C4—S1173.5 (2)C12i—C12—C13—F1110.5 (3)
C1—S1—C4—C3−0.6 (2)C3—C12—C13—F1−71.2 (3)
C1—S1—C4—C15176.6 (2)C12i—C12—C13—C14−7.9 (3)
C2—C1—C5—C621.9 (4)C3—C12—C13—C14170.46 (19)
S1—C1—C5—C6−162.0 (2)F2—C13—C14—F3i7.2 (3)
C2—C1—C5—C10−154.7 (3)F1—C13—C14—F3i122.5 (2)
S1—C1—C5—C1021.4 (3)C12—C13—C14—F3i−117.5 (3)
C10—C5—C6—C70.6 (4)F2—C13—C14—F3−113.2 (3)
C1—C5—C6—C7−176.0 (2)F1—C13—C14—F32.2 (3)
C5—C6—C7—C80.0 (4)C12—C13—C14—F3122.2 (3)
C6—C7—C8—C9−0.1 (4)F2—C13—C14—C13i127.3 (3)
C6—C7—C8—C11−179.4 (3)F1—C13—C14—C13i−117.3 (2)
C7—C8—C9—C10−0.4 (4)C12—C13—C14—C13i2.69 (11)
C11—C8—C9—C10178.9 (2)

Symmetry codes: (i) −x, y, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: NG2448).

References

  • Irie, M. (2000). Chem. Rev.100, 1685–1716. [PubMed]
  • Jacobson, R. (1998). Private communication to the Rigaku Corporation, Tokyo, Japan.
  • Kobatake, S., Kuma, S. & Irie, M. (2004). Bull. Chem. Soc. Jpn, 77, 945–951.
  • Pu, S.-Z., Liu, G., Chen, B. & Wang, R.-J. (2005). Acta Cryst. C61, o599–o601. [PubMed]
  • Pu, S.-Z., Yang, T.-S., Xu, J.-K., Li, G.-Z., Shen, L., Xiao, Q. & Chen, B. (2005). Tetrahedron, 61, 6623–6629.
  • Rigaku/MSC (2001). CrystalClear Rigaku/MSC, The Woodlands, Texas, USA.
  • Rigaku/MSC (2004). CrystalStructure Rigaku/MSC, The Woodlands, Texas, USA.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Woodward, R. B. & Hoffmann, R. (1970). The Conservation of Orbital Symmetry, pp. 98–100. Weinheim: Verlag Chemie GmbH.

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