In the crystal structure of the title charge-transfer complex, namely trans-stilbene-2,2'-(2,3,5,6-tetrafluorobenzene-1,4-diylidene)propanedinitrile (1/1) (trans-STB-TCNQF4), C14H12·C12F4N4, the planar STB and TCNQF4 molecules are stacked alternately. The structure is not isostructural with that of STB-TCNQ. No anomaly was found in the displacement parameters of any atoms, while the bond length of the central C=C moiety was shorter than the corresponding bond in ethylene. This suggests that the central C=C moiety of the STB molecule vibrates with a large amplitude, similar to the case in free STB and STB-TCNQ.
Supporting information
CCDC reference: 164645
Crystals of STB–TCNQF4 were prepared by slow cooling of a concentrated
acetone solution containing STB and TCNQF4. The complex was obtained as
needle-like dark-green crystals. The molar ratio was found to be 1:1 by
chemical analysis, i.e. the complex was STB–TCNQF4. Crystals were
slightly air sensitive.
H atoms were treated as riding atoms with a C—H distance of 0.93 Å.
Data collection: MSC/AFC Diffractometer Control Software
(Molecular Structure Corporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1995); program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: TEXSAN and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: TEXSAN.
trans-stilbene - 2,2'-(2,3,5,6-tetrafluorobenzene-1,4-diylidene)-
propanedinitrile (1/1)
top
Crystal data top
C14H12·C12F4N4 | F(000) = 464.00 |
Mr = 456.40 | Dx = 1.481 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 9.555 (2) Å | Cell parameters from 25 reflections |
b = 6.287 (2) Å | θ = 29.4–30.0° |
c = 17.295 (2) Å | µ = 0.12 mm−1 |
β = 99.99 (1)° | T = 293 K |
V = 1023.2 (4) Å3 | Needle, green |
Z = 2 | 0.2 × 0.2 × 0.2 mm |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.015 |
Radiation source: Rigaku rotating anode | θmax = 27.5°, θmin = 2.7° |
Graphite monochromator | h = −12→0 |
ω–2θ scans | k = 0→8 |
2716 measured reflections | l = −21→22 |
2347 independent reflections | 3 standard reflections every 150 reflections |
1463 reflections with I > 2σ(I) | intensity decay: 1.6% |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.124 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0513P)2 + 0.1154P] where P = (Fo2 + 2Fc2)/3 |
2347 reflections | (Δ/σ)max < 0.001 |
154 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
Crystal data top
C14H12·C12F4N4 | V = 1023.2 (4) Å3 |
Mr = 456.40 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.555 (2) Å | µ = 0.12 mm−1 |
b = 6.287 (2) Å | T = 293 K |
c = 17.295 (2) Å | 0.2 × 0.2 × 0.2 mm |
β = 99.99 (1)° | |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.015 |
2716 measured reflections | 3 standard reflections every 150 reflections |
2347 independent reflections | intensity decay: 1.6% |
1463 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.124 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.20 e Å−3 |
2347 reflections | Δρmin = −0.18 e Å−3 |
154 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
C1 | 0.15683 (17) | 0.0100 (3) | 0.08790 (10) | 0.0385 (4) | |
C2 | 0.20911 (19) | 0.1646 (3) | 0.14274 (11) | 0.0459 (5) | |
H2 | 0.1620 | 0.2942 | 0.1424 | 0.055* | |
C3 | 0.3302 (2) | 0.1288 (4) | 0.19781 (11) | 0.0494 (5) | |
H3 | 0.3639 | 0.2341 | 0.2341 | 0.059* | |
C4 | 0.40076 (19) | −0.0623 (3) | 0.19906 (11) | 0.0461 (5) | |
H4 | 0.4829 | −0.0854 | 0.2356 | 0.055* | |
C5 | 0.34932 (19) | −0.2197 (3) | 0.14593 (11) | 0.0449 (5) | |
H5 | 0.3961 | −0.3497 | 0.1473 | 0.054* | |
C6 | 0.22822 (19) | −0.1845 (3) | 0.09053 (10) | 0.0414 (4) | |
H6 | 0.1943 | −0.2911 | 0.0549 | 0.050* | |
C7 | 0.02950 (17) | 0.0600 (3) | 0.02951 (10) | 0.0414 (4) | |
H7 | −0.0137 | 0.1904 | 0.0350 | 0.050* | |
F1 | 0.60329 (11) | 0.27403 (16) | 0.11706 (6) | 0.0465 (3) | |
F2 | 0.62162 (10) | −0.38391 (16) | −0.01573 (6) | 0.0451 (3) | |
N1 | 0.8412 (2) | 0.0810 (3) | 0.23756 (11) | 0.0657 (5) | |
N2 | 0.88659 (19) | −0.4638 (3) | 0.10582 (12) | 0.0641 (5) | |
C10 | 0.62444 (15) | −0.0618 (3) | 0.05665 (9) | 0.0309 (3) | |
C11 | 0.55158 (16) | 0.1375 (3) | 0.06035 (9) | 0.0324 (4) | |
C12 | 0.56340 (17) | −0.1935 (3) | −0.00834 (10) | 0.0327 (4) | |
C13 | 0.74051 (17) | −0.1224 (3) | 0.11100 (10) | 0.0357 (4) | |
C14 | 0.79472 (18) | −0.0020 (3) | 0.17994 (11) | 0.0439 (4) | |
C15 | 0.81832 (18) | −0.3151 (3) | 0.10589 (11) | 0.0421 (4) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0306 (8) | 0.0492 (11) | 0.0366 (9) | 0.0022 (8) | 0.0081 (7) | 0.0036 (8) |
C2 | 0.0421 (10) | 0.0524 (11) | 0.0438 (10) | 0.0083 (9) | 0.0094 (8) | −0.0034 (9) |
C3 | 0.0448 (10) | 0.0637 (13) | 0.0396 (10) | −0.0017 (10) | 0.0075 (8) | −0.0094 (9) |
C4 | 0.0365 (9) | 0.0644 (13) | 0.0364 (9) | 0.0025 (9) | 0.0037 (7) | 0.0078 (9) |
C5 | 0.0402 (10) | 0.0489 (11) | 0.0462 (10) | 0.0080 (8) | 0.0090 (8) | 0.0093 (9) |
C6 | 0.0398 (9) | 0.0448 (10) | 0.0387 (9) | −0.0013 (8) | 0.0045 (7) | −0.0014 (8) |
C7 | 0.0348 (9) | 0.0452 (10) | 0.0446 (10) | 0.0081 (8) | 0.0081 (7) | 0.0015 (8) |
F1 | 0.0478 (6) | 0.0415 (6) | 0.0454 (6) | −0.0012 (5) | −0.0053 (5) | −0.0122 (5) |
F2 | 0.0459 (6) | 0.0360 (6) | 0.0510 (6) | 0.0106 (4) | 0.0015 (5) | −0.0057 (5) |
N1 | 0.0689 (12) | 0.0644 (12) | 0.0538 (10) | −0.0085 (10) | −0.0174 (9) | −0.0017 (9) |
N2 | 0.0546 (10) | 0.0612 (12) | 0.0734 (13) | 0.0212 (9) | 0.0026 (9) | 0.0085 (10) |
C10 | 0.0273 (7) | 0.0343 (9) | 0.0312 (8) | −0.0019 (7) | 0.0059 (6) | 0.0032 (7) |
C11 | 0.0332 (8) | 0.0316 (8) | 0.0317 (8) | −0.0038 (7) | 0.0040 (6) | −0.0042 (7) |
C12 | 0.0324 (8) | 0.0296 (8) | 0.0369 (8) | 0.0030 (7) | 0.0085 (7) | −0.0010 (7) |
C13 | 0.0302 (8) | 0.0378 (9) | 0.0381 (9) | −0.0005 (7) | 0.0037 (6) | 0.0036 (7) |
C14 | 0.0383 (9) | 0.0453 (11) | 0.0436 (10) | −0.0019 (8) | −0.0055 (8) | 0.0061 (8) |
C15 | 0.0344 (9) | 0.0469 (11) | 0.0427 (10) | 0.0033 (8) | 0.0004 (7) | 0.0064 (8) |
Geometric parameters (Å, º) top
C1—C2 | 1.389 (3) | C7—H7 | 0.93 |
C1—C6 | 1.397 (3) | F1—C11 | 1.3324 (17) |
C1—C7 | 1.474 (2) | F2—C12 | 1.3356 (18) |
C2—C3 | 1.383 (3) | N1—C14 | 1.144 (2) |
C2—H2 | 0.93 | N2—C15 | 1.140 (2) |
C3—C4 | 1.376 (3) | C10—C13 | 1.377 (2) |
C3—H3 | 0.93 | C10—C12 | 1.436 (2) |
C4—C5 | 1.382 (3) | C10—C11 | 1.440 (2) |
C4—H4 | 0.93 | C11—C12ii | 1.341 (2) |
C5—C6 | 1.386 (2) | C12—C11ii | 1.341 (2) |
C5—H5 | 0.93 | C13—C14 | 1.431 (3) |
C6—H6 | 0.93 | C13—C15 | 1.432 (3) |
C7—C7i | 1.315 (4) | | |
| | | |
C2—C1—C6 | 118.33 (15) | C7i—C7—C1 | 126.9 (2) |
C2—C1—C7 | 118.34 (17) | C7i—C7—H7 | 116.5 |
C6—C1—C7 | 123.32 (16) | C1—C7—H7 | 116.5 |
C3—C2—C1 | 120.98 (18) | C13—C10—C12 | 123.00 (15) |
C3—C2—H2 | 119.5 | C13—C10—C11 | 123.25 (15) |
C1—C2—H2 | 119.5 | C12—C10—C11 | 113.74 (13) |
C4—C3—C2 | 120.14 (18) | F1—C11—C12ii | 118.74 (15) |
C4—C3—H3 | 119.9 | F1—C11—C10 | 118.22 (13) |
C2—C3—H3 | 119.9 | C12ii—C11—C10 | 123.02 (14) |
C3—C4—C5 | 119.87 (16) | F2—C12—C11ii | 118.53 (15) |
C3—C4—H4 | 120.1 | F2—C12—C10 | 118.19 (14) |
C5—C4—H4 | 120.1 | C11ii—C12—C10 | 123.24 (15) |
C4—C5—C6 | 120.22 (18) | C10—C13—C14 | 123.69 (16) |
C4—C5—H5 | 119.9 | C10—C13—C15 | 123.84 (16) |
C6—C5—H5 | 119.9 | C14—C13—C15 | 112.46 (14) |
C5—C6—C1 | 120.43 (17) | N1—C14—C13 | 175.2 (2) |
C5—C6—H6 | 119.8 | N2—C15—C13 | 175.5 (2) |
C1—C6—H6 | 119.8 | | |
| | | |
C6—C1—C2—C3 | 1.1 (3) | C12—C10—C11—F1 | −177.68 (13) |
C7—C1—C2—C3 | −178.47 (17) | C13—C10—C11—C12ii | −178.37 (16) |
C1—C2—C3—C4 | −0.1 (3) | C12—C10—C11—C12ii | 0.7 (3) |
C2—C3—C4—C5 | −1.0 (3) | C13—C10—C12—F2 | 0.6 (2) |
C3—C4—C5—C6 | 1.1 (3) | C11—C10—C12—F2 | −178.46 (13) |
C4—C5—C6—C1 | −0.1 (3) | C13—C10—C12—C11ii | 178.37 (16) |
C2—C1—C6—C5 | −1.0 (3) | C11—C10—C12—C11ii | −0.7 (3) |
C7—C1—C6—C5 | 178.56 (17) | C12—C10—C13—C14 | −174.10 (16) |
C2—C1—C7—C7i | 175.4 (2) | C11—C10—C13—C14 | 4.8 (3) |
C6—C1—C7—C7i | −4.2 (4) | C12—C10—C13—C15 | 4.3 (3) |
C13—C10—C11—F1 | 3.3 (2) | C11—C10—C13—C15 | −176.74 (16) |
Symmetry codes: (i) −x, −y, −z; (ii) −x+1, −y, −z. |
Experimental details
Crystal data |
Chemical formula | C14H12·C12F4N4 |
Mr | 456.40 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 9.555 (2), 6.287 (2), 17.295 (2) |
β (°) | 99.99 (1) |
V (Å3) | 1023.2 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.2 × 0.2 × 0.2 |
|
Data collection |
Diffractometer | Rigaku AFC-7R diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2716, 2347, 1463 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.124, 1.03 |
No. of reflections | 2347 |
No. of parameters | 154 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.20, −0.18 |
Selected bond lengths (Å) topC1—C2 | 1.389 (3) | N1—C14 | 1.144 (2) |
C1—C6 | 1.397 (3) | N2—C15 | 1.140 (2) |
C1—C7 | 1.474 (2) | C10—C13 | 1.377 (2) |
C2—C3 | 1.383 (3) | C10—C12 | 1.436 (2) |
C3—C4 | 1.376 (3) | C10—C11 | 1.440 (2) |
C4—C5 | 1.382 (3) | C11—C12ii | 1.341 (2) |
C5—C6 | 1.386 (2) | C12—C11ii | 1.341 (2) |
C7—C7i | 1.315 (4) | C13—C14 | 1.431 (3) |
F1—C11 | 1.3324 (17) | C13—C15 | 1.432 (3) |
F2—C12 | 1.3356 (18) | | |
Symmetry codes: (i) −x, −y, −z; (ii) −x+1, −y, −z. |
The dynamic co-operation between molecular (atomic) dynamics and change in electronic state is of current interest (Mitani et al., 1988; Nakasuji et al., 1991). Although most studies in the field have been performed on systems with hydrogen bonds, recently, the authors have demonstrated the interplay in a high-Tc organic superconductor, i.e. κ-(BEDT-TTF)2Cu[N(CN)2]Br [BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene; Saito et al., 1999; Akutsu et al., 2000]. As another approach, the authors have shown that reorientation of the molecule involved in the charge transfer (CT) occurs in the crystalline lattice of the CT complex trans-stilbene–TCNQ (STB-TCNQ, where TCNQ is 7,7,8,8-tetracyano-p-quinodimethane; Saito et al., 2000). We report here the crystal structure of STB–TCNQF4 (TCNQF4 is 7,7,8,8-tetracyano-2,3,5,6-tetrafluoro-p-quinodimethane), (I), which is a halogenated derivative of STB–TCNQ.
A view of the two molecules in the asymmetric unit is shown in Fig. 1 and the packing is shown in Fig. 2. The STB molecule lies about an inversion center at (0, 0, 0) and the TCNQF4 molecule lies about an inversion center at (1/2, 0, 0) at room temperature, and these are ordered in space group P21/n, in contrast to what was found in the structure of STB—TCNQ in space group C2/m (Zobel & Ruban, 1983). Thus, the crystal structure of the present complex is not isostructural with that of STB–TCNQ. Molecules of STB and TCNQF4 stack alternately to form a column along the a direction. The STB and TCNQF4 molecules overlap with a slip of half the molecular length (Fig. 2). This is different from the exact overlapping and ring-over-ring arrangement in STB–TCNQ. In STB–TCNQF4 the interplanar angle between the unique ring of the STB molecule and that of the TCNQF4 is 5.59 (11)°. The separations of the ring centroids from the plane of the adjacent overlapped rings are 3.255 (unique STB ring plane centroid to TCNQF4 plane) and 3.355 Å (TCNQF4 centroid to unique STB ring plane). No unusual displacement parameters were found for any atoms.
The central C═C bond length in the STB molecule is 1.315 (4) Å, which is equal to the corresponding length in STB–TCNQ [1.318 (6) Å; Zobel & Ruban, 1983] within experimental error. The angle of the central Ph—C═C moiety is 126.9 (2)°. While the bond length suggests a localization of electron density on the central C═C moiety, the Ph—C═C angle indicates delocalization on the central C═C moiety. Since the degree of CT of (I) was estimated to be ca 0.2 e by IR measurement, the central C═C bond in (I) should be longer than the bond of 1.337 (6) Å in ethylene (International Tables for X-ray Crystallography, Vol. III, 1968). Short central C═C bonds have been widely observed in the structural results of free STB and its derivatives (Finder et al., 1974; Bernstein, 1975; Bouwstra et al., 1984). Ogawa et al. (1992) proposed a possible cause for this anomalously short C═C bond, i.e. that molecules oscillate in a shallow potential with a large amplitude while maintaining the orientation of the phenyl rings. The existance of this type of molecular vibration in STB was supported by a lattice dynamical calculation (Saito & Ikemoto, 1996). The observed short C═C bond implies that the STB molecule vibrates in the assumed manner with a large amplitude, as proposed by Ogawa et al. (1992), even in (I).