3,3,4,4,5,5-Hexa­fluoro-1,2-bis(3-methyl­benzo­[b]-2-thienyl)­cyclo­pentene

The title compound, C₂₃H₁₄F₆S₂, was crystallized from a PMMA/chloro­form solution (PMMA = polymethylmethacryl­ate), and its crystal structure was determined. The mol­ecule adopts a photoactive antiparallel conformation. The distance between the two reactive C atoms was determined to be 3.560 (7)Å. The molecule has crystallographic twofold rotation symmetry.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.061
• wR factor = 0.119
• Data-to-parameter ratio = 11.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSTM_02  Alert C The ratio of Tmax/Tmin expected RT(exp) is > 1.10
          Absorption corrections should be applied.
          Tmin and Tmax expected:      0.829     0.938
          RT(exp) =      1.131

REFLT_03
         From the CIF: _diffrn_reflns_theta_max           25.00
         From the CIF: _reflns_number_total               1644
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         1797
         Completeness (_total/calc)             91.49%
          Alert C: < 95% complete

PLAT_031  Alert C Refined Extinction Parameter within Range ......       2.53 Sigma


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 3 Alert Level C = Please check

---

S1. Comment

Due to good thermal stability and high fatigue resistance, photochromic diarylethenes have potential application for optoelectronic devices, such as optical memories and switches (Irie, 2000; Fernandez-Asebes & Lehn, 1999). Diarylethenes usually have two conformations in the solid state, parallel or antiparallel (Kobatake et al., 1999; Shibata et al., 2002).

The title compound (BTPF), (I), is a bis(2-thienyl)perfluorocyclopentene derivative. It has attract our attention due to its interesting non-linear optical properties (Sun et al., 2002). Unlike most diarylethenes crystals recrystallized from organic solution (Pu et al., 2003), the crystals of BTPF were obtained from a PMMA/chloroform solution. The polymer in chloroform causes deposition of BTPF/PMMA films, which act as membranous substrate that mediate the growth of BTPF crystals. As a result, perfect yellow block-shaped single crystals were obtained.

The X-ray crystallographic study showed that BTPF is packed in the antiparallel conformation. The general view of a molecule, together with the atom-numbering scheme is shown in Fig. 1. The distance between the reactive carbons (C5 and C5#) is 3.56 Å, which is close enough for photocyclization reaction (Ramamurthy & Venkatesan, 1987). Although the two benzo[b]thiophene rings adopt different orientations with respect to the perfluorocyclopentene ring, the crystallographic analysis data revealed that the corresponding bond lengths, bond angles and dihedral angles between the least-squares planes are the same.

S2. Experimental

The title compound was prepared according to a method described in the literature (Sun et al., 2002). Single crystals were obtained from a PMMA/chloroform solution·The weight ratio of PMMA and BTPF is 5:1.

Computing details

Data collection: XSCANS (Bruker, 1997); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. View of the molecule of BTPF with the atomic numbering scheme. Displacement ellipsoids are drawn at the 35% probability level.
	Fig. 2. A packing view along the b direction.

3,3,4,4,5,5-Hexafluoro-1,2-bis(3-methylbenzo[b]-2-thienyl)cyclopentene

Crystal data

C23H14F6S2	F(000) = 952
Mr = 468.46	Dx = 1.522 Mg m^−3
Monoclinic, C2/c	Melting point: 465 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 18.8350 (18) Å	Cell parameters from 36 reflections
b = 9.3507 (9) Å	θ = 3.8–12.6°
c = 11.643 (2) Å	µ = 0.32 mm^−1
β = 94.653 (11)°	T = 293 K
V = 2043.8 (5) Å^3	Block, yellow
Z = 4	0.6 × 0.6 × 0.2 mm

Data collection

Bruker P4 diffractometer	Rint = 0.024
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = −1→22
ω scans	k = −1→11
2244 measured reflections	l = −13→13
1644 independent reflections	3 standard reflections every 100 reflections
1198 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.061	H-atom parameters constrained
wR(F^2) = 0.119	w = 1/[σ^2(Fo^2) + (0.001P)^2 + 7P] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max < 0.001
1644 reflections	Δρmax = 0.44 e Å^−3
142 parameters	Δρmin = −0.48 e Å^−3
0 restraints	Extinction correction: SHELXTL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00043 (17)

Special details

Experimental. Unit cell was obtained and refined by 38 well centered reflections with 3.8°<θ<12.6°. Data collection was monitored by three standards every 100 reflection collected. No decay was observed except the statistic fluctuation in the range of ±4.3%. Raw intensities were corrected for Lorentz and polarization effects. Direct phase determination yielded the positions of S, F and the most C atoms, and the other C atoms were located in successive difference Fourier syntheses. Hydrogen atoms were placed at their geometrically calculated position and riding on their parent atoms in the final refinement. All non-hydrongen atoms were subjected to anisotropic refinement.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

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 (Ų)

	x	y	z	Uiso*/Ueq
S1	0.13825 (6)	0.25372 (13)	0.41799 (9)	0.0768 (4)
F1	0.1163 (2)	−0.0506 (4)	0.2268 (6)	0.216 (3)
F2	0.0830 (3)	−0.0508 (4)	0.3958 (4)	0.178 (2)
F3	0.0143 (3)	−0.2008 (6)	0.1690 (5)	0.276 (4)
C1	0.0350 (2)	0.1263 (4)	0.2693 (4)	0.0696 (11)
C2	0.0614 (3)	−0.0235 (5)	0.2882 (6)	0.0996 (16)
C3	0.0000	−0.1180 (8)	0.2500	0.111 (3)
C4	0.0826 (2)	0.2478 (4)	0.2899 (3)	0.0637 (9)
C5	0.09140 (19)	0.3622 (4)	0.2213 (3)	0.0612 (9)
C6	0.14380 (19)	0.4607 (4)	0.2717 (3)	0.0598 (9)
C7	0.17473 (19)	0.4144 (4)	0.3788 (3)	0.0662 (10)
C8	0.2282 (2)	0.4931 (5)	0.4399 (4)	0.0818 (13)
H8A	0.2484	0.4611	0.5108	0.098*
C9	0.2502 (2)	0.6172 (6)	0.3939 (4)	0.0897 (14)
H9A	0.2867	0.6692	0.4330	0.108*
C10	0.2193 (2)	0.6679 (5)	0.2893 (4)	0.0865 (13)
H10A	0.2342	0.7545	0.2602	0.104*
C11	0.1667 (2)	0.5907 (5)	0.2288 (4)	0.0741 (11)
H11A	0.1463	0.6251	0.1588	0.089*
C12	0.0551 (2)	0.3857 (5)	0.1035 (3)	0.0806 (13)
H12A	0.0224	0.3088	0.0849	0.121*
H12B	0.0901	0.3886	0.0480	0.121*
H12C	0.0296	0.4746	0.1020	0.121*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0858 (7)	0.0741 (7)	0.0690 (7)	0.0105 (6)	−0.0024 (5)	0.0156 (6)
F1	0.176 (4)	0.077 (2)	0.421 (8)	0.041 (2)	0.175 (5)	0.042 (4)
F2	0.229 (5)	0.077 (2)	0.210 (4)	−0.004 (3)	−0.098 (4)	0.048 (3)
F3	0.227 (5)	0.249 (6)	0.333 (7)	0.138 (5)	−0.090 (6)	−0.193 (5)
C1	0.085 (3)	0.055 (2)	0.071 (3)	0.0069 (19)	0.017 (2)	0.007 (2)
C2	0.102 (4)	0.061 (3)	0.139 (5)	0.011 (3)	0.029 (4)	0.014 (3)
C3	0.146 (7)	0.054 (4)	0.136 (7)	0.000	0.025 (6)	0.000
C4	0.068 (2)	0.058 (2)	0.065 (2)	0.0081 (19)	0.0069 (18)	0.0049 (19)
C5	0.064 (2)	0.062 (2)	0.058 (2)	0.0079 (19)	0.0046 (17)	0.0036 (18)
C6	0.059 (2)	0.058 (2)	0.062 (2)	0.0074 (18)	0.0067 (16)	0.0030 (18)
C7	0.062 (2)	0.070 (3)	0.067 (2)	0.010 (2)	0.0043 (18)	0.000 (2)
C8	0.069 (3)	0.097 (4)	0.078 (3)	0.006 (3)	−0.001 (2)	−0.010 (3)
C9	0.071 (3)	0.101 (4)	0.097 (4)	−0.011 (3)	0.010 (2)	−0.022 (3)
C10	0.079 (3)	0.079 (3)	0.104 (4)	−0.012 (3)	0.020 (3)	−0.003 (3)
C11	0.074 (3)	0.072 (3)	0.076 (3)	0.002 (2)	0.008 (2)	0.008 (2)
C12	0.088 (3)	0.089 (3)	0.064 (2)	−0.011 (3)	−0.001 (2)	0.015 (2)

Geometric parameters (Å, º)

S1—C7	1.728 (4)	C6—C11	1.396 (5)
S1—C4	1.753 (4)	C6—C7	1.402 (5)
F1—C2	1.328 (6)	C7—C8	1.395 (5)
F2—C2	1.311 (7)	C8—C9	1.356 (6)
F3—C3	1.266 (5)	C8—H8A	0.93
C1—C1^i	1.359 (8)	C9—C10	1.391 (6)
C1—C4	1.455 (5)	C9—H9A	0.93
C1—C2	1.496 (6)	C10—C11	1.372 (6)
C2—C3	1.494 (6)	C10—H10A	0.93
C3—F3^i	1.266 (5)	C11—H11A	0.93
C3—C2^i	1.494 (6)	C12—H12A	0.96
C4—C5	1.353 (5)	C12—H12B	0.96
C5—C6	1.440 (5)	C12—H12C	0.96
C5—C12	1.498 (5)
C7—S1—C4	91.48 (19)	C11—C6—C5	129.3 (4)
C1^i—C1—C4	128.5 (2)	C7—C6—C5	112.8 (3)
C1^i—C1—C2	110.5 (3)	C8—C7—C6	121.4 (4)
C4—C1—C2	121.0 (4)	C8—C7—S1	127.6 (3)
F2—C2—F1	106.4 (5)	C6—C7—S1	111.0 (3)
F2—C2—C3	110.0 (4)	C9—C8—C7	118.8 (4)
F1—C2—C3	110.1 (5)	C9—C8—H8A	120.6
F2—C2—C1	113.3 (5)	C7—C8—H8A	120.6
F1—C2—C1	111.3 (4)	C8—C9—C10	121.1 (5)
C3—C2—C1	105.7 (5)	C8—C9—H9A	119.4
F3^i—C3—F3	104.6 (9)	C10—C9—H9A	119.4
F3^i—C3—C2	110.3 (3)	C11—C10—C9	120.3 (5)
F3—C3—C2	112.1 (4)	C11—C10—H10A	119.9
F3^i—C3—C2^i	112.1 (4)	C9—C10—H10A	119.9
F3—C3—C2^i	110.3 (3)	C10—C11—C6	120.4 (4)
C2—C3—C2^i	107.5 (6)	C10—C11—H11A	119.8
C5—C4—C1	128.6 (4)	C6—C11—H11A	119.8
C5—C4—S1	112.6 (3)	C5—C12—H12A	109.5
C1—C4—S1	118.8 (3)	C5—C12—H12B	109.5
C4—C5—C6	112.2 (3)	H12A—C12—H12B	109.5
C4—C5—C12	126.0 (4)	C5—C12—H12C	109.5
C6—C5—C12	121.7 (3)	H12A—C12—H12C	109.5
C11—C6—C7	118.0 (4)	H12B—C12—H12C	109.5

Symmetry code: (i) −x, y, −z+1/2.