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The title compound, (4-EtC6H4)2C=C=C=C=C=C(4-EtC6H4)2 or C38H36, was prepared from 1,1,6,6-tetra­kis(4-ethyl­phen­yl)-2,4-hexa­diyne-1,6-diol by reduction with SnCl2 in an acidic medium. The mol­ecule has a centre of symmetry at the mid-point of the cumulative double bonds, in which longer and shorter bonds alternate.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807032576/is2187sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807032576/is2187Isup2.hkl
Contains datablock I

CCDC reference: 657717

Key indicators

  • Single-crystal X-ray study
  • T = 90 K
  • Mean [sigma](C-C)= 0.003 Å
  • R factor = 0.058
  • wR factor = 0.166
  • Data-to-parameter ratio = 17.2

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Comment top

Compounds with highly cumulative unsaturated carbon-carbon bonds are of interest because of their potential application for electronic and optical materials (Kminek et al., 1993; Hino et al., 2003). Hexapentaenes contain six collinear carbon atoms with five cumulative double bonds, and various derivatives have been synthesized (Kuhn & Wallenfels, 1938; Kuwatani et al., 2005). Nevertheless, there have been only two reports on the structural characterization of hexapentaenes. One has 2,2,5,5-tetramethylcyclohexyl groups at the termini of cumulated double bonds (Irngartinger & Jäger, 1976), and atomic coordinates were not provided in the report. The other is 1,1,6,6-tetraphenyl-1,2,3,4,5-hexapentaene reported in 1953 (Woolfson, 1953), which is a pioneering work, although the quality of the analysis does not meet modern standards. Here, we report a novel hexapentaene that has four 4-ethylphenyl groups at the termini of a hexapentaene moiety.

The molecular structure of the title compound, (I), is shown in Fig. 1. The molecule has a symmetry centre, which corresponds to a crystallographic inversion centre, at the middle of six collinear carbon atoms. The longer and shorter bonds alternate in the cumulative double bonds, and C1—C2, C2—C3 and C3—C3i were 1.349 (2), 1.251 (2) and 1.310 (3) Å, respectively, showing a similar tendency to those of reported examples [symmetry code: (i) 1 - x, 1 - y, 1 - z]. The two benzene rings at the termini were rotated by 22.07 (10)° and 42.01 (7)° from the central mean plane formed by C1—C4, C12, C1i—C4i and C12i. These were rotated in the same direction, whereas it was proposed in 1,1,6,6-tetraphenyl-1,2,3,4,5-hexapentaene (Woolfson, 1953) that corresponding phenyl groups were rotated in opposite direction by 32°. Packing of the molecules is shown in Fig. 2. The molecules of (I) align along the [1 1 0] direction so as to make the central mean planes coplanar; the largest deviation between the mean planes of the neighbouring molecules along the direction is 0.037 (9) Å. The coplanes are stacked along the [1 1 0] direction. The distances between the least-square planes of the coplanes, i.e. the planes C1—C4/C12/C1i—C4i/C12i/C1ii—C4ii/C12ii/C1iii—C4iii/C12iii and C1iv—C4iv/C12iv/C1v—C4v/C12v/C1vi—C4vi/C12vi/C1vii– C4vii/C12vii [symmetry codes: (ii) 2 - x, -y, 1 - z; (iii) 1 + x, y - 1, z; (iv) 1 + x, y, z; (v) 2 - x, 1 - y, 1 - z; (vi) x, 1 + y, z; (vii) 1 - x, 2 - y, 1 - z] are 4.12 (2) Å, while in tetraphenylhexapentaene, showing a similar packing motif, the distance between the corresponding planes is ca 4 Å.

Related literature top

For related literature, see: Hino et al. (2003); Irngartinger & Jäger (1976); Kminek et al. (1993); Kuhn & Wallenfels (1938); Kuwatani et al. (2005); Woolfson (1953).

Experimental top

The title compound was prepared according to the reported method (Kuwatani et al., 2005). Hydrogen chloride in diethyl ether (2.0 M, 4.76 ml, 9.52 mmol) was added to a solution of 1,1,6,6-tetra(4-ethylphenyl)-2,4-hexadiyne-1,6-diol (1.366 g, 2.38 mmol) and SnCl2 (1.354 g, 7.14 mmol) in THF (15 ml) at 0 °C and stirred for 1 h at 0 °C. Hydrochloric acid (1 N) was added to the dark red solution and extracted with diethyl ether. The organic layer was combined and dried over MgSO4, and volatiles were removed in vacuo. The residue was purified by column chromatography on silica gel (hexane/EtOAc = 95/5) to give the title compound as red crystals (yield 0.965 g, 82%; m.p. 125–127 °C). 1H NMR (CDCl3, Me4Si): δ 1.27 (t, 7.6 Hz, 12H), 2.68 (q, 7.6 Hz, 8H), 7.21 (d, 8.2 Hz, 8H), 7.49 (d, 8.2 Hz, 8H). 13C NMR (CDCl3, Me4Si): δ 15.46, 28.75, 123.79 (q), 126.04 (q), 128.03 (CH), 129.34 (CH), 135.76 (q, Ar), 144.87 (q, Ar), 147.84 (q). IR (neat, cm-1): 830, 913, 1181, 1457, 1505, 1602, 1656, 1794, 1910, 1999, 2865, 2927, 2964. Calcd for C38H36, C 92.64, H 7.36; found C 92.53, H 7.48.

Refinement top

All H atoms were found on a difference map and were subsequently treated as riding atoms with C—H distances of 0.95, 0.99 and 0.98 Å for phenyl, methylene and methyl, respectively. The Uiso's of H atoms were fixed to have 1.2Ueq and 1.5Ueq of the parent atoms for methylene and phenyl, and methyl, respectively.

Structure description top

Compounds with highly cumulative unsaturated carbon-carbon bonds are of interest because of their potential application for electronic and optical materials (Kminek et al., 1993; Hino et al., 2003). Hexapentaenes contain six collinear carbon atoms with five cumulative double bonds, and various derivatives have been synthesized (Kuhn & Wallenfels, 1938; Kuwatani et al., 2005). Nevertheless, there have been only two reports on the structural characterization of hexapentaenes. One has 2,2,5,5-tetramethylcyclohexyl groups at the termini of cumulated double bonds (Irngartinger & Jäger, 1976), and atomic coordinates were not provided in the report. The other is 1,1,6,6-tetraphenyl-1,2,3,4,5-hexapentaene reported in 1953 (Woolfson, 1953), which is a pioneering work, although the quality of the analysis does not meet modern standards. Here, we report a novel hexapentaene that has four 4-ethylphenyl groups at the termini of a hexapentaene moiety.

The molecular structure of the title compound, (I), is shown in Fig. 1. The molecule has a symmetry centre, which corresponds to a crystallographic inversion centre, at the middle of six collinear carbon atoms. The longer and shorter bonds alternate in the cumulative double bonds, and C1—C2, C2—C3 and C3—C3i were 1.349 (2), 1.251 (2) and 1.310 (3) Å, respectively, showing a similar tendency to those of reported examples [symmetry code: (i) 1 - x, 1 - y, 1 - z]. The two benzene rings at the termini were rotated by 22.07 (10)° and 42.01 (7)° from the central mean plane formed by C1—C4, C12, C1i—C4i and C12i. These were rotated in the same direction, whereas it was proposed in 1,1,6,6-tetraphenyl-1,2,3,4,5-hexapentaene (Woolfson, 1953) that corresponding phenyl groups were rotated in opposite direction by 32°. Packing of the molecules is shown in Fig. 2. The molecules of (I) align along the [1 1 0] direction so as to make the central mean planes coplanar; the largest deviation between the mean planes of the neighbouring molecules along the direction is 0.037 (9) Å. The coplanes are stacked along the [1 1 0] direction. The distances between the least-square planes of the coplanes, i.e. the planes C1—C4/C12/C1i—C4i/C12i/C1ii—C4ii/C12ii/C1iii—C4iii/C12iii and C1iv—C4iv/C12iv/C1v—C4v/C12v/C1vi—C4vi/C12vi/C1vii– C4vii/C12vii [symmetry codes: (ii) 2 - x, -y, 1 - z; (iii) 1 + x, y - 1, z; (iv) 1 + x, y, z; (v) 2 - x, 1 - y, 1 - z; (vi) x, 1 + y, z; (vii) 1 - x, 2 - y, 1 - z] are 4.12 (2) Å, while in tetraphenylhexapentaene, showing a similar packing motif, the distance between the corresponding planes is ca 4 Å.

For related literature, see: Hino et al. (2003); Irngartinger & Jäger (1976); Kminek et al. (1993); Kuhn & Wallenfels (1938); Kuwatani et al. (2005); Woolfson (1953).

Computing details top

Data collection: CrystalClear SM (Rigaku/MSC, 2005); cell refinement: CrystalClear SM; data reduction: CrystalClear SM; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (i) 1 - x, 1 - y, 1 - z].
[Figure 2] Fig. 2. A packing view of (I).
1,1,6,6-Tetrakis(4-ethylphenyl)-1,2,3,4,5-hexapentaene top
Crystal data top
C38H36Z = 1
Mr = 492.67F(000) = 264
Triclinic, P1Dx = 1.172 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.233 (3) ÅCell parameters from 1421 reflections
b = 7.819 (3) Åθ = 2.7–31.8°
c = 15.060 (6) ŵ = 0.07 mm1
α = 93.849 (7)°T = 90 K
β = 96.353 (6)°Plate, red
γ = 105.908 (8)°0.20 × 0.08 × 0.03 mm
V = 697.8 (5) Å3
Data collection top
Rigaku AFC-8 with Saturn70 CCD detector
diffractometer
2271 reflections with I > 2σ(I)
Radiation source: fine-focus rotating anodeRint = 0.058
Confocal monochromatorθmax = 27.5°, θmin = 1.4°
Detector resolution: 28.5714 pixels mm-1h = 88
ω scansk = 1010
10184 measured reflectionsl = 1919
3169 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)] = 0.058Hydrogen site location: difference Fourier map
wR(F2) = 0.166H-atom parameters constrained
S = 1.10 w = 1/[σ2(Fo2) + (0.0818P)2 + 0.1721P]
where P = (Fo2 + 2Fc2)/3
3169 reflections(Δ/σ)max < 0.001
184 parametersΔρmax = 0.29 e Å3
0 restraintsΔρmin = 0.23 e Å3
Crystal data top
C38H36γ = 105.908 (8)°
Mr = 492.67V = 697.8 (5) Å3
Triclinic, P1Z = 1
a = 6.233 (3) ÅMo Kα radiation
b = 7.819 (3) ŵ = 0.07 mm1
c = 15.060 (6) ÅT = 90 K
α = 93.849 (7)°0.20 × 0.08 × 0.03 mm
β = 96.353 (6)°
Data collection top
Rigaku AFC-8 with Saturn70 CCD detector
diffractometer
2271 reflections with I > 2σ(I)
10184 measured reflectionsRint = 0.058
3169 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0580 restraints
wR(F2) = 0.166H-atom parameters constrained
S = 1.10Δρmax = 0.29 e Å3
3169 reflectionsΔρmin = 0.23 e Å3
184 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 > 2σ(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
xyzUiso*/Ueq
C10.2372 (3)0.5597 (2)0.31075 (10)0.0184 (3)
C20.3440 (3)0.5306 (2)0.38872 (11)0.0213 (4)
C30.4442 (3)0.5093 (2)0.46204 (10)0.0219 (4)
C40.2487 (3)0.4593 (2)0.22565 (10)0.0188 (3)
C50.0806 (3)0.4334 (2)0.15174 (11)0.0210 (4)
H50.03880.48630.15520.025*
C60.0876 (3)0.3317 (2)0.07406 (11)0.0224 (4)
H70.02760.31620.02480.027*
C70.2590 (3)0.2514 (2)0.06604 (11)0.0203 (4)
C80.4270 (3)0.2776 (2)0.13952 (11)0.0219 (4)
H80.54560.22380.13580.026*
C90.4237 (3)0.3804 (2)0.21753 (11)0.0214 (4)
H90.54110.39790.26610.026*
C100.2656 (3)0.1413 (2)0.01962 (11)0.0246 (4)
H10A0.11350.10350.05470.030*
H10B0.30640.03220.00410.030*
C110.4330 (3)0.2429 (3)0.07754 (12)0.0311 (4)
H11A0.43290.16500.13130.047*
H11B0.58400.28060.04320.047*
H11C0.38970.34830.09530.047*
C120.1089 (3)0.6941 (2)0.31389 (10)0.0193 (4)
C130.0162 (3)0.7073 (2)0.38373 (11)0.0229 (4)
H130.02730.62420.42740.027*
C140.1250 (3)0.8395 (2)0.39083 (12)0.0251 (4)
H140.21010.84500.43900.030*
C150.1108 (3)0.9648 (2)0.32793 (11)0.0233 (4)
C160.0145 (3)0.9506 (2)0.25801 (11)0.0230 (4)
H160.02691.03450.21470.028*
C170.1212 (3)0.8180 (2)0.25001 (11)0.0215 (4)
H170.20330.81070.20100.026*
C180.2284 (4)1.1101 (3)0.33273 (14)0.0367 (5)
H18A0.11191.22690.34470.044*
H18B0.31421.10760.27300.044*
C190.3871 (3)1.0999 (3)0.40214 (13)0.0320 (4)
H19A0.46141.19490.39650.048*
H19B0.30221.11500.46230.048*
H19C0.50090.98330.39270.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0181 (7)0.0202 (8)0.0174 (8)0.0065 (6)0.0007 (6)0.0055 (6)
C20.0223 (8)0.0226 (8)0.0204 (8)0.0097 (7)0.0000 (6)0.0016 (6)
C30.0245 (8)0.0225 (8)0.0210 (8)0.0112 (7)0.0013 (6)0.0019 (6)
C40.0210 (8)0.0197 (8)0.0163 (8)0.0068 (6)0.0005 (6)0.0050 (6)
C50.0212 (8)0.0209 (8)0.0219 (8)0.0084 (6)0.0008 (6)0.0053 (6)
C60.0223 (8)0.0223 (8)0.0206 (8)0.0055 (7)0.0049 (6)0.0040 (6)
C70.0226 (8)0.0173 (8)0.0193 (8)0.0023 (6)0.0026 (6)0.0042 (6)
C80.0229 (8)0.0240 (8)0.0223 (8)0.0115 (7)0.0030 (6)0.0059 (6)
C90.0215 (8)0.0250 (8)0.0179 (8)0.0081 (7)0.0019 (6)0.0050 (6)
C100.0284 (9)0.0213 (8)0.0225 (8)0.0050 (7)0.0018 (7)0.0017 (7)
C110.0297 (9)0.0341 (10)0.0264 (9)0.0038 (8)0.0062 (7)0.0002 (8)
C120.0183 (8)0.0221 (8)0.0172 (8)0.0072 (6)0.0025 (6)0.0027 (6)
C130.0256 (8)0.0235 (8)0.0218 (8)0.0099 (7)0.0021 (6)0.0073 (6)
C140.0282 (9)0.0275 (9)0.0239 (9)0.0126 (7)0.0076 (7)0.0064 (7)
C150.0265 (9)0.0222 (8)0.0239 (9)0.0117 (7)0.0020 (7)0.0036 (7)
C160.0268 (9)0.0230 (8)0.0213 (8)0.0101 (7)0.0020 (6)0.0069 (6)
C170.0225 (8)0.0250 (8)0.0182 (8)0.0094 (7)0.0001 (6)0.0043 (6)
C180.0477 (12)0.0315 (10)0.0433 (11)0.0250 (9)0.0166 (9)0.0153 (9)
C190.0367 (10)0.0335 (10)0.0307 (10)0.0199 (9)0.0008 (8)0.0007 (8)
Geometric parameters (Å, º) top
C1—C21.349 (2)C11—H11B0.9800
C1—C41.477 (2)C11—H11C0.9800
C1—C121.486 (2)C12—C131.391 (2)
C2—C31.251 (2)C12—C171.404 (2)
C3—C3i1.310 (3)C13—C141.387 (2)
C4—C91.404 (2)C13—H130.9500
C4—C51.405 (2)C14—C151.400 (2)
C5—C61.381 (2)C14—H140.9500
C5—H50.9500C15—C161.395 (2)
C6—C71.392 (2)C15—C181.513 (2)
C6—H70.9500C16—C171.382 (2)
C7—C81.399 (2)C16—H160.9500
C7—C101.513 (2)C17—H170.9500
C8—C91.384 (2)C18—C191.508 (3)
C8—H80.9500C18—H18A0.9900
C9—H90.9500C18—H18B0.9900
C10—C111.523 (2)C19—H19A0.9800
C10—H10A0.9900C19—H19B0.9800
C10—H10B0.9900C19—H19C0.9800
C11—H11A0.9800
C2—C1—C4120.27 (14)H11A—C11—H11C109.5
C2—C1—C12117.92 (14)H11B—C11—H11C109.5
C4—C1—C12121.81 (13)C13—C12—C17118.07 (15)
C1—C2—C3177.96 (17)C13—C12—C1120.59 (14)
C2—C3—C3i177.9 (3)C17—C12—C1121.22 (15)
C9—C4—C5118.00 (14)C14—C13—C12121.30 (15)
C9—C4—C1120.79 (13)C14—C13—H13119.3
C5—C4—C1121.15 (14)C12—C13—H13119.3
C6—C5—C4120.54 (15)C13—C14—C15120.82 (16)
C6—C5—H5119.7C13—C14—H14119.6
C4—C5—H5119.7C15—C14—H14119.6
C5—C6—C7121.71 (14)C16—C15—C14117.61 (15)
C5—C6—H7119.1C16—C15—C18119.85 (15)
C7—C6—H7119.1C14—C15—C18122.53 (16)
C6—C7—C8117.80 (14)C17—C16—C15121.84 (15)
C6—C7—C10121.20 (14)C17—C16—H16119.1
C8—C7—C10121.00 (15)C15—C16—H16119.1
C9—C8—C7121.23 (15)C16—C17—C12120.34 (15)
C9—C8—H8119.4C16—C17—H17119.8
C7—C8—H8119.4C12—C17—H17119.8
C8—C9—C4120.71 (14)C19—C18—C15116.43 (16)
C8—C9—H9119.6C19—C18—H18A108.2
C4—C9—H9119.6C15—C18—H18A108.2
C7—C10—C11112.81 (14)C19—C18—H18B108.2
C7—C10—H10A109.0C15—C18—H18B108.2
C11—C10—H10A109.0H18A—C18—H18B107.3
C7—C10—H10B109.0C18—C19—H19A109.5
C11—C10—H10B109.0C18—C19—H19B109.5
H10A—C10—H10B107.8H19A—C19—H19B109.5
C10—C11—H11A109.5C18—C19—H19C109.5
C10—C11—H11B109.5H19A—C19—H19C109.5
H11A—C11—H11B109.5H19B—C19—H19C109.5
C10—C11—H11C109.5
C2—C1—C4—C921.7 (2)C2—C1—C12—C1339.3 (2)
C12—C1—C4—C9158.52 (15)C4—C1—C12—C13140.43 (16)
C2—C1—C4—C5155.61 (16)C2—C1—C12—C17136.72 (17)
C12—C1—C4—C524.1 (2)C4—C1—C12—C1743.5 (2)
C9—C4—C5—C60.7 (2)C17—C12—C13—C140.4 (2)
C1—C4—C5—C6176.76 (15)C1—C12—C13—C14175.78 (14)
C4—C5—C6—C70.2 (3)C12—C13—C14—C150.4 (3)
C5—C6—C7—C80.4 (2)C13—C14—C15—C160.5 (3)
C5—C6—C7—C10179.58 (15)C13—C14—C15—C18179.49 (17)
C6—C7—C8—C90.2 (2)C14—C15—C16—C170.2 (2)
C10—C7—C8—C9178.97 (15)C18—C15—C16—C17178.78 (16)
C7—C8—C9—C41.1 (3)C15—C16—C17—C121.1 (2)
C5—C4—C9—C81.3 (2)C13—C12—C17—C161.1 (2)
C1—C4—C9—C8176.17 (15)C1—C12—C17—C16175.03 (14)
C6—C7—C10—C11101.36 (19)C16—C15—C18—C19171.39 (16)
C8—C7—C10—C1177.8 (2)C14—C15—C18—C197.6 (3)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC38H36
Mr492.67
Crystal system, space groupTriclinic, P1
Temperature (K)90
a, b, c (Å)6.233 (3), 7.819 (3), 15.060 (6)
α, β, γ (°)93.849 (7), 96.353 (6), 105.908 (8)
V3)697.8 (5)
Z1
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.20 × 0.08 × 0.03
Data collection
DiffractometerRigaku AFC-8 with Saturn70 CCD detector
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
10184, 3169, 2271
Rint0.058
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.058, 0.166, 1.10
No. of reflections3169
No. of parameters184
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.29, 0.23

Computer programs: CrystalClear SM (Rigaku/MSC, 2005), CrystalClear SM, SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
C1—C21.349 (2)C3—C3i1.310 (3)
C2—C31.251 (2)
C1—C2—C3177.96 (17)C2—C3—C3i177.9 (3)
C2—C1—C4—C921.7 (2)C2—C1—C12—C1339.3 (2)
C2—C1—C4—C5155.61 (16)C2—C1—C12—C17136.72 (17)
Symmetry code: (i) x+1, y+1, z+1.
 

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