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In the title complex, C6F6·C14H12, nearly parallel mol­ecules of trans-stilbene and librationally disordered hexa­fluoro­benzene form a mixed stack, with each molecule lying on an independent inversion centre. Adjacent stacks pack together in a herring-bone manner.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101013294/bm1463sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101013294/bm1463Isup2.hkl
Contains datablock I

CCDC reference: 175082

Comment top

While studying arene–perfluoroarene interactions and their possible uses in crystal engineering (Dai et al., 1999; Collings, Batsanov et al., 2001; Collings, Roscoe et al., 2001), we found that arenes and perfluoroarenes of wildly mismatched geometry can be cocrystallized. Trans-stilbene (TSB) is known to form 1:1 complexes with matching perfluorinated species, viz. decafluoro–trans-azabenzene (Bruce et al., 1987) and decafluoro–trans-stilbene (Coates et al., 1998). On the other hand, TSB forms complexes with electron acceptors of rather disparate geometry, e.g. 1:1 complexes with pyromellitic dianhydride (Kodama & Kumakura, 1974) or tetracyanoquinodimethane (Zobel & Ruban, 1983), and 1:2 complexes with 1,2,4,5-tetracyanobenzene (Agostini et al., 1988) or 1,3,5-trinitrobenzene (Bar & Bernstein, 1978). All these are molecular complexes which exhibit no significant charge transfer, and as most arene–perfluoroarene systems behave in the same way, we expected that TSB could also form complexes with geometrically mismatched perfluoroarenes.

Colourless crystals grown from HFB proved to be the 1:1 complex HFB.TSB, (I). Both the TSB and the HFB molecules have crystallographic Ci symmetry (Fig. 1). The TSB molecule shows no sign of disorder, unlike the structures of TSB itself (Bouwstra et al., 1984) and most of its molecular complexes; these all display the same mode of disorder, namely an overlap of two molecular positions, related by a 180° rotation around the C1···C1' vector. In (I), the TSB molecule is slightly twisted, the planes of the phenyl ring and the olefinic moiety forming a dihedral angle (ϕ) of 7.2 (7)°. Such a conformation is typical for both TSB and its molecular complexes, but contrasts drastically with the twisted conformation observed in the gas phase, where <ϕ2>1/2 = 31 (5)° (Traettenberg et al., 1975). The bond distances in (I) agree with those seen in pure TSB at 113 K (Hoekstra et al., 1975) or at room temperature, if proper account was taken of the disorder (Bouwstra et al., 1984). Those studies of TSB where the disorder remained unresolved gave spuriously shortened central CC bond distances (Finder et al., 1974; Bernstein, 1975).

Notwithstanding the low temperature, the HFB molecule shows high atomic displacement parameters, suggesting librational disorder. Attempts to model the disorder by various superpositions of two or three different orientations resulted in unstable refinements if no constraints were applied, or (if severely constrained) converged at much higher R indices than the single-position model. The molecule is probably disordered within one wide flat-bottomed potential well, rather than between separate wells.

The crystal packing of (I) (Fig. 2) comprises mixed stair-like stacks, parallel to the crystallographic a axis. Within each stack, the benzene rings of the HFB and TSB molecules are almost parallel [dihedral angle 3.4 (2)°] and overlap with an average interplanar separation of 3.45 (5) Å. Each HFB molecule is sandwiched between two parallel phenyl rings, and each phenyl ring is sandwiched between a parallel HFB molecule on one side and a phenyl ring inclined by 45.9 (2)° on the other. The latter phenyl ring belongs to a TSB molecule of an adjacent stack, related by the operation of a 21 screw axis. These stacks run in the same direction but have different orientations of the molecular planes, making inter-stack dihedral angles of up to 50.9 (2)° (for HFB/HFB). Thus, the packing of (I) can be described as a combination of stacking and herring-bone motifs, in contrast with pure HFB (Boden et al., 1973) and pure TSB, both of which display a purely herring-bone packing, with all molecules making T-fashion (edge-to-face) contacts and with no stacking interactions.

The packing of (I) is relatively loose: the volume per HFB.TSB unit is larger by 3% than the sum of the molecular volumes in solid TSB at 113 K (249.5 Å3; Hoekstra et al., 1975) and in solid HFB at 120 K (147.3 Å3; Boden et al., 1973). Such loose packing may explain the disorder of the HFB molecule in (I).

Related literature top

For related literature, see: Agostini et al. (1988); Bar & Bernstein (1978); Bernstein (1975); Boden et al. (1973); Bouwstra et al. (1984); Bruce et al. (1987); Coates et al. (1998); Collings, Batsanov, Howard & Marder (2001); Collings, Roscoe, Thomas, Batsanov, Stimson, Howard & Marder (2001); Dai et al. (1999); Finder et al. (1974); Hoekstra et al. (1975); Kodama & Kumakura (1974); Traettenberg et al. (1975); Zobel & Ruban (1983).

Experimental top

For the preparation of the title adduct, TSB (0.1 g) was dissolved in HFB (1 ml) with warming. Slow evaporation of the solution at room temperature yielded single crystals of (I).

Refinement top

All H atoms were refined and the range of phenyl-ring C—H distances was 0.98 (5)–1.01 (5) Å and C7—H was 1.07 (5) Å.

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The molecules of HFB (solid bonds) and TSB (hollow bonds) in (I), projected onto their mean planes. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 1 - x, 1 - y, 1 - z; (ii) -x, 1 - y, 1 - z.]
[Figure 2] Fig. 2. Crystal packing of (I), with H atoms omitted for clarity.
hexafluorobenzene–trans-stilbene (1/1) top
Crystal data top
C6F6·C14H12F(000) = 372
Mr = 366.30Dx = 1.488 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 11.401 (3) ÅCell parameters from 369 reflections
b = 6.118 (2) Åθ = 10.2–24.2°
c = 12.262 (4) ŵ = 0.13 mm1
β = 107.09 (2)°T = 120 K
V = 817.5 (4) Å3Plate, colourless
Z = 20.30 × 0.30 × 0.06 mm
Data collection top
SMART 1K CCD area-detector
diffractometer
1125 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.049
Graphite monochromatorθmax = 25.4°, θmin = 1.9°
Detector resolution: 8 pixels mm-1h = 1313
ω scansk = 67
4709 measured reflectionsl = 148
1501 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.078Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.207All H-atom parameters refined
S = 1.11 w = 1/[σ2(Fo2) + (0.069P)2 + 2.177P]
where P = (Fo2 + 2Fc2)/3
1501 reflections(Δ/σ)max = 0.001
142 parametersΔρmax = 0.44 e Å3
0 restraintsΔρmin = 0.50 e Å3
Crystal data top
C6F6·C14H12V = 817.5 (4) Å3
Mr = 366.30Z = 2
Monoclinic, P21/cMo Kα radiation
a = 11.401 (3) ŵ = 0.13 mm1
b = 6.118 (2) ÅT = 120 K
c = 12.262 (4) Å0.30 × 0.30 × 0.06 mm
β = 107.09 (2)°
Data collection top
SMART 1K CCD area-detector
diffractometer
1125 reflections with I > 2σ(I)
4709 measured reflectionsRint = 0.049
1501 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0780 restraints
wR(F2) = 0.207All H-atom parameters refined
S = 1.11Δρmax = 0.44 e Å3
1501 reflectionsΔρmin = 0.50 e Å3
142 parameters
Special details top

Experimental. The data collection nominally covered over a hemisphere of reciprocal space, by a combination of 4 sets of ω scans, each set at different ϕ and/or 2θ angles and each scan (30 sec exposure) covering 0.3° in ω. Crystal to detector distance 4.51 cm. Crystal decay was monitored by repeating 50 initial frames at the end of data collection and comparing 67 duplicate reflections.

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. C(Ph)—H bond distances 0.98 (5) to 1.01 (5), C7—H 1.07 (5) Å.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.3941 (3)0.4501 (6)0.5970 (3)0.0293 (9)
C20.3226 (3)0.2752 (7)0.6122 (3)0.0317 (9)
H20.315 (4)0.143 (8)0.563 (4)0.046 (12)*
C30.2619 (4)0.2807 (7)0.6944 (3)0.0340 (9)
H30.210 (4)0.151 (7)0.704 (3)0.038 (11)*
C40.2694 (3)0.4634 (7)0.7625 (3)0.0343 (9)
H40.226 (4)0.473 (7)0.821 (3)0.037 (11)*
C50.3391 (3)0.6422 (7)0.7481 (3)0.0333 (9)
H50.343 (4)0.774 (7)0.798 (4)0.041 (12)*
C60.4013 (3)0.6356 (7)0.6662 (3)0.0317 (9)
H60.455 (4)0.759 (7)0.663 (3)0.031 (10)*
C70.4596 (3)0.4298 (7)0.5088 (3)0.0320 (9)
H70.443 (4)0.284 (8)0.458 (4)0.052 (13)*
C80.0128 (4)0.3535 (8)0.4202 (3)0.0427 (11)
C90.0752 (4)0.5457 (8)0.4346 (3)0.0420 (11)
C100.0627 (4)0.6928 (7)0.5141 (4)0.0444 (11)
F10.0240 (3)0.2090 (7)0.3421 (3)0.1042 (16)
F20.1500 (3)0.5884 (7)0.3707 (3)0.0932 (15)
F30.1249 (3)0.8817 (5)0.5263 (4)0.0995 (16)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0243 (18)0.038 (2)0.0244 (17)0.0043 (16)0.0050 (14)0.0039 (16)
C20.030 (2)0.030 (2)0.034 (2)0.0003 (16)0.0066 (16)0.0001 (17)
C30.031 (2)0.034 (2)0.038 (2)0.0014 (17)0.0099 (17)0.0072 (17)
C40.029 (2)0.047 (2)0.0269 (18)0.0037 (18)0.0085 (16)0.0045 (18)
C50.0267 (19)0.040 (2)0.032 (2)0.0018 (17)0.0076 (16)0.0089 (18)
C60.0257 (19)0.034 (2)0.034 (2)0.0044 (17)0.0068 (15)0.0030 (17)
C70.032 (2)0.035 (2)0.0277 (18)0.0018 (16)0.0068 (15)0.0005 (17)
C80.034 (2)0.051 (3)0.036 (2)0.015 (2)0.0013 (18)0.019 (2)
C90.026 (2)0.067 (3)0.035 (2)0.009 (2)0.0132 (17)0.018 (2)
C100.029 (2)0.023 (2)0.067 (3)0.0051 (17)0.008 (2)0.005 (2)
F10.078 (2)0.138 (3)0.073 (2)0.054 (2)0.0149 (17)0.071 (2)
F20.0393 (16)0.184 (4)0.0660 (19)0.022 (2)0.0308 (14)0.064 (2)
F30.0492 (18)0.0328 (16)0.177 (4)0.0151 (14)0.029 (2)0.019 (2)
Geometric parameters (Å, º) top
C1—C21.390 (5)C6—H60.98 (4)
C1—C61.405 (5)C7—C7i1.323 (8)
C1—C71.490 (5)C7—H71.07 (5)
C2—C31.381 (5)C8—F11.337 (5)
C2—H21.00 (5)C8—C91.359 (7)
C3—C41.383 (6)C8—C10ii1.370 (7)
C3—H31.01 (4)C9—F21.342 (5)
C4—C51.393 (6)C9—C101.365 (6)
C4—H40.99 (4)C10—F31.341 (5)
C5—C61.390 (5)C10—C8ii1.370 (7)
C5—H51.00 (4)
C2—C1—C6118.3 (3)C5—C6—C1120.5 (4)
C2—C1—C7118.2 (4)C5—C6—H6118 (2)
C6—C1—C7123.6 (4)C1—C6—H6122 (2)
C3—C2—C1121.2 (4)C7i—C7—C1125.9 (5)
C3—C2—H2119 (3)C7i—C7—H7117 (2)
C1—C2—H2120 (3)C1—C7—H7117 (2)
C2—C3—C4120.4 (4)F1—C8—C9120.5 (4)
C2—C3—H3119 (2)F1—C8—C10ii119.6 (5)
C4—C3—H3120 (2)C9—C8—C10ii119.9 (4)
C3—C4—C5119.6 (4)F2—C9—C8119.4 (4)
C3—C4—H4122 (2)F2—C9—C10120.4 (5)
C5—C4—H4118 (2)C8—C9—C10120.2 (4)
C6—C5—C4120.0 (4)F3—C10—C9119.0 (5)
C6—C5—H5121 (2)F3—C10—C8ii121.1 (5)
C4—C5—H5119 (2)C9—C10—C8ii120.0 (4)
C6—C1—C7—C7i6.7 (7)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC6F6·C14H12
Mr366.30
Crystal system, space groupMonoclinic, P21/c
Temperature (K)120
a, b, c (Å)11.401 (3), 6.118 (2), 12.262 (4)
β (°) 107.09 (2)
V3)817.5 (4)
Z2
Radiation typeMo Kα
µ (mm1)0.13
Crystal size (mm)0.30 × 0.30 × 0.06
Data collection
DiffractometerSMART 1K CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4709, 1501, 1125
Rint0.049
(sin θ/λ)max1)0.602
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.078, 0.207, 1.11
No. of reflections1501
No. of parameters142
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.44, 0.50

Computer programs: SMART (Bruker, 1999), SMART, SAINT (Bruker, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
C1—C71.490 (5)C8—C10ii1.370 (7)
C7—C7i1.323 (8)C9—F21.342 (5)
C8—F11.337 (5)C9—C101.365 (6)
C8—C91.359 (7)C10—F31.341 (5)
C2—C1—C6118.3 (3)C7i—C7—C1125.9 (5)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1.
 

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