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The title triene, C18H10F6, was prepared via the Pd0 coupling reaction of (E)-(1,2-di­fluoro-1,2-ethenediyl)­bis­(tri­butyl­stan­nane) with (Z)-β-iodo-α,β-di­fluoro­styrene in N,N′-dimethylformamide/tetrahydrofuran. The crystal structure shows the product to be the 1E,3E,5E isomer. Due to steric interactions between F atoms, the double bonds are not coplanar. The planes defined by the two terminal double bonds are almost perpendicular.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100007502/bk1534sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100007502/bk1534Isup2.hkl
Contains datablock I

CCDC reference: 150365

Comment top

The chemistry of polyfluorinated polyene systems (beyond dienes) is virtually unknown. The few compounds reported were generally mixtures of all possible E/Z isomers (Yagupol'skii et al., 1976, 1977, 1985). This work was initiated to develop methodology for the stereospecific preparation of fluorinated polyenes in order to compare the effects of the fluorine substituents on conjugation, reactivity, and stability of the polyene. The titled triene was stereospecifically prepared via the route shown below. \sch

Fig. 1 shows that the triene is the (1E,3E,5E)-isomer and that the conjugated system has a conformation that is significantly distorted from overall planarity by intramolecular steric interactions. Although the overall molecule is not planar, the phenyl rings 1 (C7—C12) and 2 (C13—C18) and individual double-bond moieties (Db1: C7, F1, C1, C2, F2, C3; Db2: C2, F3, C3, C4, F4, C5; Db3: C4, F5, C5, C6, F7, C13) are planar. The largest r.m.s. deviation from least-squares plane is 0.03 Å for Db3. Ring 1 and Db1 are nearly coplanar [dihedral angle = 5.6 (2)°] as are ring 2 and Db3 [dihedral angle = 2.1 (2)°]. However, the double-bond moieties are not coplanar. Rotations of about 42° about the C2—C3 and C4—C5 bonds reduce intramolecular steric repulsion between adjacent fluoro-substituents. [Note: The barrier to full rotation (perpendicular double bonds) about these bonds should be similar to that of the central bond in 1,3-butadiene, calculated value = 5.9 kcal mol−1 (Head-Gordon & Pople, 1993).] The longest F···F intramolecular distance is 0.375 Å shorter than the shortest F···F intermolecular distance (see Table 2). An additional result of these two rotations is that the phenyl rings are nearly perpendicular [dihedral angle = 88.3 (1)°]. Even though the double-bond moieties are not coplanar, the shortening of the C2—C3 and C4—C5 bonds show that they are part of a delocalized π system.

Fig. 2 shows the that packing of the molecules is organized by π···π and CH···π interactions. The molecules form a network via π···π interactions between adjacent (phenyl ring-double bond) π systems across inversion centers. The ring 1-π system (ring 1 and Db1) overlap occurs across the (1/2,0,1/2) set of inversion centers such that C7 is approximately centered over the adjacent phenyl ring (π···π spacing = 3.537 Å, C7 – Xc1i = 3.570 Å; Xc1i is the centroid of symmetry-related Ring 1, i = 1 − x, 2 − y, 1 − z). The ring 2-π system (ring 2 and Db3) has a greater degree of overlap and a closer π···π spacing·This interaction occurs across the (01/20) set of inversion centers such that C6 is approximately centered over the adjacent phenyl ring (π···π spacing = 3.427 Å, C6···Xc2ii = 3.455 Å; Xc2ii is the centroid of symmetry-related ring 2, ii = −x, 1 − y, −z). The network also includes C15—H15···ring 1 interactions that form dimers across the (1/2,1/2,0) set of inversion centers (H15···Xc1iii = 2.89 Å, C15—H15···Xc1iii = 143°; iii = 1 − x, 1 − y, −z). The crystal morphology appears to correlate with these interactions. The direction of the longest molecular dimension is approximately parallel to the (a+b)-face diagonal direction. The binding faces for the largest crystal dimension are the (110) and (110) faces. The direction of the C15—H15···ring 1 interaction is approximately parallel to the (a-c)-face diagonal. The binding faces for the smallest crystal dimension are the (101) and (101) faces.

Experimental top

A three-neck 250 ml round bottom flask equipped with a teflon-coated stir bar, a cold water condenser attached to a nitrogen source, a thermometer, and a rubber septum was charged with CuI (1.48 g, 7.7 mmol), N,N'-dimethylformamide (35 ml), tetrahydrofuran (THF) (35 ml), Pd(PPh3)4 (0.44 g, 0.4 mmol), (E)-n-Bu3SnCFCFn-Bu3 (4.95 g), and (Z)-PhCFCFI (4.12 g, 15.5 mmol). The reaction mixture was stirred at room temperature for 14 h, at 310 K for 14 h, and at 318 K for 10 h.

The majority of the THF was removed by rotary evaporation. The residue was diluted with 80 ml of H2O, extracted with Et2O (4 x 80 ml), and the combined ether layers dried over anhydrous MgSO4. The majority of the solvent was removed by rotary evaporation; the residue was poured onto a silica-gel chromatgraphy column and eluted with pentane, Rf = 0.88. Removal of most of the pentane yielded a mixture of the title compound, n-Bu3SnI and (Z)-PhCFCFI. This mixture was recrystallized twice from hexane to give 1.0 g (40% yield) of (1E,3E,5E)-1,2,3,4,5,6-hexafluoro-1,6-diphenylhexatriene as white crystals, mp. 344 K.

19F NMR (CDCl3) δ-140.8 (dt, 2 F, J = 126 Hz, 24 Hz), −149.4 (m, 2 F), −162.8 (ddd, 2 F, J = 127 Hz, 15 Hz, 6 Hz). 1H NMR (CDCl3) δ 7.8 (m, 2H), 7.5 (m, 3H). 13C NMR (CDCl3) δ 151.2 (dd, J = 248 Hz, 42 Hz), 140.2 (m), 130.7 (s), 128.7 (s), 126.4 (t, J = 8 Hz), 117.4 (d, J = 337 Hz). HRMS calcd. for C18H10F6 = 340.0687, obsd. = 340.0679.

Computing details top

Data collection: CAD4 Operations Manual (Enraf-Nonius, 1977); cell refinement: CAD4 Operations Manual; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXTL (Sheldrick, 1995); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. View of title compound. Displacement ellipsoids are shown at the 35% level.
[Figure 2] Fig. 2. Packing diagram of the title compound.
(I) top
Crystal data top
C18H10F6Z = 2
Mr = 340.26F(000) = 344
Triclinic, P1Dx = 1.528 Mg m3
a = 9.138 (1) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.793 (2) ÅCell parameters from 45 reflections
c = 8.249 (1) Åθ = 11.7–17.4°
α = 90.76 (1)°µ = 0.14 mm1
β = 94.26 (1)°T = 210 K
γ = 65.75 (1)°Plate, colorless
V = 739.6 (2) Å30.53 × 0.23 × 0.09 mm
Data collection top
Enraf-Nonius CAD4
diffractometer
Rint = 0.042
Radiation source: fine-focus sealed tubeθmax = 25.0°, θmin = 2.0°
Graphite monochromatorh = 1010
θ–2θ scansk = 1212
4307 measured reflectionsl = 95
2587 independent reflections4 standard reflections every 120 min
1706 reflections with I > 2σ(I) intensity decay: <2
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.039H-atom parameters constrained
wR(F2) = 0.122Calculated w = 1/[σ2(Fo2) + (0.0533P)2 + 0.1953P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max = 0.001
2587 reflectionsΔρmax = 0.20 e Å3
218 parametersΔρmin = 0.19 e Å3
0 restraintsExtinction correction: SHELXTL (Sheldrick, 1995), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0074 (40)
Crystal data top
C18H10F6γ = 65.75 (1)°
Mr = 340.26V = 739.6 (2) Å3
Triclinic, P1Z = 2
a = 9.138 (1) ÅMo Kα radiation
b = 10.793 (2) ŵ = 0.14 mm1
c = 8.249 (1) ÅT = 210 K
α = 90.76 (1)°0.53 × 0.23 × 0.09 mm
β = 94.26 (1)°
Data collection top
Enraf-Nonius CAD4
diffractometer
Rint = 0.042
4307 measured reflections4 standard reflections every 120 min
2587 independent reflections intensity decay: <2
1706 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0390 restraints
wR(F2) = 0.122H-atom parameters constrained
S = 1.05Δρmax = 0.20 e Å3
2587 reflectionsΔρmin = 0.19 e Å3
218 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 on F2 for ALL reflections except for 0 with very negative F2 or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating R factor obs 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
xyzUiso*/Ueq
C10.4979 (3)0.7999 (2)0.2747 (3)0.0480 (6)
F10.3703 (2)0.8514 (2)0.1642 (2)0.0723 (5)
C20.5281 (3)0.6768 (2)0.3303 (3)0.0507 (6)
F20.6617 (2)0.6131 (2)0.4307 (2)0.0802 (5)
C30.4352 (3)0.5968 (2)0.3005 (3)0.0530 (6)
F30.5264 (2)0.46226 (14)0.2918 (2)0.0759 (5)
C40.2762 (3)0.6379 (2)0.2924 (3)0.0511 (6)
F40.1864 (2)0.76861 (14)0.3238 (2)0.0681 (5)
C50.1833 (3)0.5574 (2)0.2646 (3)0.0479 (6)
F50.0607 (2)0.59361 (15)0.3616 (2)0.0642 (4)
C60.2036 (3)0.4577 (2)0.1600 (3)0.0447 (5)
F60.3244 (2)0.43336 (14)0.0607 (2)0.0590 (4)
C70.5783 (3)0.8909 (2)0.3122 (3)0.0457 (5)
C80.5230 (3)1.0142 (2)0.2271 (3)0.0560 (6)
H80.43761.03660.14820.067*
C90.5947 (4)1.1034 (3)0.2598 (4)0.0661 (7)
H90.55651.18610.20350.079*
C100.7213 (4)1.0708 (3)0.3745 (4)0.0673 (8)
H100.76951.13090.39540.081*
C110.7771 (3)0.9497 (3)0.4588 (3)0.0657 (7)
H110.86270.92820.53730.079*
C120.7075 (3)0.8593 (3)0.4281 (3)0.0559 (6)
H120.74710.77690.48510.067*
C130.1195 (3)0.3690 (2)0.1339 (3)0.0433 (5)
C140.1655 (3)0.2723 (2)0.0137 (3)0.0521 (6)
H140.24910.26540.04860.063*
C150.0898 (3)0.1863 (3)0.0154 (3)0.0608 (7)
H150.12290.12190.09630.073*
C160.0337 (3)0.1951 (3)0.0744 (4)0.0637 (7)
H160.08440.13670.05550.076*
C170.0823 (3)0.2913 (3)0.1929 (4)0.0690 (8)
H170.16770.29870.25280.083*
C180.0060 (3)0.3772 (3)0.2245 (3)0.0600 (7)
H180.03880.44060.30650.072*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0435 (12)0.0494 (13)0.0461 (13)0.0150 (10)0.0023 (10)0.0001 (10)
F10.0760 (10)0.0684 (9)0.0759 (10)0.0382 (8)0.0302 (8)0.0197 (8)
C20.0398 (12)0.0515 (14)0.0567 (14)0.0158 (11)0.0046 (11)0.0014 (11)
F20.0547 (9)0.0675 (10)0.1184 (14)0.0301 (8)0.0296 (9)0.0313 (9)
C30.0499 (14)0.0444 (13)0.063 (2)0.0184 (11)0.0011 (12)0.0000 (11)
F30.0498 (8)0.0467 (8)0.1265 (15)0.0165 (7)0.0023 (9)0.0019 (8)
C40.0499 (14)0.0477 (13)0.0545 (14)0.0195 (11)0.0011 (11)0.0047 (11)
F40.0523 (8)0.0559 (9)0.0925 (11)0.0196 (7)0.0043 (8)0.0277 (8)
C50.0413 (12)0.0527 (13)0.0470 (13)0.0165 (11)0.0045 (11)0.0038 (11)
F50.0552 (8)0.0750 (10)0.0687 (9)0.0309 (7)0.0209 (7)0.0246 (8)
C60.0413 (12)0.0455 (12)0.0427 (12)0.0131 (10)0.0038 (10)0.0011 (10)
F60.0593 (8)0.0617 (8)0.0638 (9)0.0303 (7)0.0226 (7)0.0138 (7)
C70.0452 (12)0.0480 (13)0.0438 (12)0.0180 (10)0.0095 (10)0.0070 (10)
C80.0578 (15)0.0515 (14)0.0576 (15)0.0215 (12)0.0030 (12)0.0002 (11)
C90.086 (2)0.0514 (15)0.068 (2)0.0337 (14)0.017 (2)0.0036 (13)
C100.082 (2)0.073 (2)0.067 (2)0.049 (2)0.023 (2)0.0190 (15)
C110.065 (2)0.082 (2)0.061 (2)0.043 (2)0.0002 (13)0.0093 (14)
C120.0577 (15)0.0563 (14)0.0561 (15)0.0258 (12)0.0034 (12)0.0021 (12)
C130.0412 (12)0.0396 (11)0.0442 (12)0.0122 (10)0.0003 (10)0.0035 (9)
C140.0432 (12)0.0511 (13)0.0592 (15)0.0166 (11)0.0049 (11)0.0075 (11)
C150.060 (2)0.0519 (14)0.069 (2)0.0222 (13)0.0024 (14)0.0128 (12)
C160.062 (2)0.0497 (14)0.083 (2)0.0274 (13)0.0005 (15)0.0015 (13)
C170.071 (2)0.063 (2)0.084 (2)0.0350 (14)0.025 (2)0.0009 (15)
C180.072 (2)0.0531 (14)0.062 (2)0.0303 (13)0.0195 (14)0.0073 (12)
Geometric parameters (Å, º) top
C1—C21.322 (3)C9—H90.93
C1—F11.350 (3)C10—C111.370 (4)
C1—C71.467 (3)C10—H100.93
C2—F21.350 (3)C11—C121.378 (4)
C2—C31.447 (3)C11—H110.93
C3—C41.330 (3)C12—H120.93
C3—F31.349 (3)C13—C181.386 (3)
C4—F41.342 (3)C13—C141.387 (3)
C4—C51.448 (3)C14—C151.376 (3)
C5—C61.332 (3)C14—H140.93
C5—F51.347 (2)C15—C161.365 (4)
C6—F61.360 (2)C15—H150.93
C6—C131.459 (3)C16—C171.375 (4)
C7—C121.391 (3)C16—H160.93
C7—C81.392 (3)C17—C181.382 (4)
C8—C91.384 (4)C17—H170.93
C8—H80.93C18—H180.93
C9—C101.367 (4)
F1···F42.636 (2)F4···F52.614 (2)
F2···F32.624 (2)F2···F5i3.025 (2)
F3···F62.659 (2)
C2—C1—F1114.5 (2)C9—C10—C11120.0 (3)
C2—C1—C7131.4 (2)C9—C10—H10120.0
F1—C1—C7114.1 (2)C11—C10—H10120.0
C1—C2—F2118.4 (2)C10—C11—C12120.5 (3)
C1—C2—C3128.9 (2)C10—C11—H11119.7
F2—C2—C3112.8 (2)C12—C11—H11119.7
C4—C3—F3117.8 (2)C11—C12—C7120.3 (2)
C4—C3—C2128.5 (2)C11—C12—H12119.9
F3—C3—C2113.6 (2)C7—C12—H12119.9
C3—C4—F4117.8 (2)C18—C13—C14118.1 (2)
C3—C4—C5128.4 (2)C18—C13—C6122.7 (2)
F4—C4—C5113.6 (2)C14—C13—C6119.2 (2)
C6—C5—F5118.7 (2)C15—C14—C13121.3 (2)
C6—C5—C4129.3 (2)C15—C14—H14119.3
F5—C5—C4112.1 (2)C13—C14—H14119.3
C5—C6—F6114.6 (2)C16—C15—C14120.2 (2)
C5—C6—C13131.3 (2)C16—C15—H15119.9
F6—C6—C13114.2 (2)C14—C15—H15119.9
C12—C7—C8118.6 (2)C15—C16—C17119.4 (3)
C12—C7—C1123.0 (2)C15—C16—H16120.3
C8—C7—C1118.4 (2)C17—C16—H16120.3
C9—C8—C7120.2 (2)C16—C17—C18121.0 (3)
C9—C8—H8119.9C16—C17—H17119.5
C7—C8—H8119.9C18—C17—H17119.5
C10—C9—C8120.4 (3)C17—C18—C13120.0 (2)
C10—C9—H9119.8C17—C18—H18120.0
C8—C9—H9119.8C13—C18—H18120.0
F1—C1—C2—F2174.4 (2)C2—C1—C7—C8176.9 (2)
C7—C1—C2—F25.8 (4)F1—C1—C7—C83.3 (3)
F1—C1—C2—C36.4 (4)C12—C7—C8—C90.9 (3)
C7—C1—C2—C3173.4 (2)C1—C7—C8—C9179.4 (2)
C1—C2—C3—C440.2 (4)C7—C8—C9—C100.7 (4)
F2—C2—C3—C4139.0 (3)C8—C9—C10—C110.5 (4)
C1—C2—C3—F3144.8 (3)C9—C10—C11—C120.5 (4)
F2—C2—C3—F336.0 (3)C10—C11—C12—C70.7 (4)
F3—C3—C4—F4170.9 (2)C8—C7—C12—C110.9 (3)
C2—C3—C4—F43.9 (4)C1—C7—C12—C11179.4 (2)
F3—C3—C4—C54.4 (4)C5—C6—C13—C180.2 (4)
C2—C3—C4—C5179.2 (3)F6—C6—C13—C18179.3 (2)
C3—C4—C5—C642.0 (4)C5—C6—C13—C14179.6 (2)
F4—C4—C5—C6142.6 (2)F6—C6—C13—C140.9 (3)
C3—C4—C5—F5138.1 (3)C18—C13—C14—C150.3 (3)
F4—C4—C5—F537.3 (3)C6—C13—C14—C15180.0 (2)
F5—C5—C6—F6176.4 (2)C13—C14—C15—C160.3 (4)
C4—C5—C6—F63.5 (4)C14—C15—C16—C170.5 (4)
F5—C5—C6—C134.1 (4)C15—C16—C17—C181.2 (4)
C4—C5—C6—C13176.0 (2)C16—C17—C18—C131.3 (4)
C2—C1—C7—C122.8 (4)C14—C13—C18—C170.5 (4)
F1—C1—C7—C12177.0 (2)C6—C13—C18—C17179.3 (2)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC18H10F6
Mr340.26
Crystal system, space groupTriclinic, P1
Temperature (K)210
a, b, c (Å)9.138 (1), 10.793 (2), 8.249 (1)
α, β, γ (°)90.76 (1), 94.26 (1), 65.75 (1)
V3)739.6 (2)
Z2
Radiation typeMo Kα
µ (mm1)0.14
Crystal size (mm)0.53 × 0.23 × 0.09
Data collection
DiffractometerEnraf-Nonius CAD4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4307, 2587, 1706
Rint0.042
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.039, 0.122, 1.05
No. of reflections2587
No. of parameters218
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.20, 0.19

Computer programs: CAD4 Operations Manual (Enraf-Nonius, 1977), CAD4 Operations Manual, MolEN (Fair, 1990), SHELXTL (Sheldrick, 1995), SHELXTL.

Selected geometric parameters (Å, º) top
C1—C21.322 (3)C4—F41.342 (3)
C1—F11.350 (3)C4—C51.448 (3)
C1—C71.467 (3)C5—C61.332 (3)
C2—F21.350 (3)C5—F51.347 (2)
C2—C31.447 (3)C6—F61.360 (2)
C3—C41.330 (3)C6—C131.459 (3)
C3—F31.349 (3)C7—C121.391 (3)
F1···F42.636 (2)F4···F52.614 (2)
F2···F32.624 (2)F2···F5i3.025 (2)
F3···F62.659 (2)
C2—C1—F1114.5 (2)C3—C4—F4117.8 (2)
C2—C1—C7131.4 (2)C3—C4—C5128.4 (2)
F1—C1—C7114.1 (2)F4—C4—C5113.6 (2)
C1—C2—F2118.4 (2)C6—C5—F5118.7 (2)
C1—C2—C3128.9 (2)C6—C5—C4129.3 (2)
F2—C2—C3112.8 (2)F5—C5—C4112.1 (2)
C4—C3—F3117.8 (2)C5—C6—F6114.6 (2)
C4—C3—C2128.5 (2)C5—C6—C13131.3 (2)
F3—C3—C2113.6 (2)F6—C6—C13114.2 (2)
F1—C1—C2—F2174.4 (2)C3—C4—C5—C642.0 (4)
C7—C1—C2—C3173.4 (2)F4—C4—C5—F537.3 (3)
C1—C2—C3—C440.2 (4)F5—C5—C6—F6176.4 (2)
F2—C2—C3—F336.0 (3)C4—C5—C6—C13176.0 (2)
F3—C3—C4—F4170.9 (2)C2—C1—C7—C122.8 (4)
C2—C3—C4—C5179.2 (3)C5—C6—C13—C14179.6 (2)
Symmetry code: (i) x+1, y+1, z+1.
 

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