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The dihedral angle between the least-squares planes through the C atoms of the six-membered rings of the title indene dimer, C18H16, is 85.53 (11)°. The five-membered ring in the indene moiety is nearly planar [torsion angles: -0.4 (3), 0.1 (4), 0.3 (4), -0.6 (3) and 0.6 (3)°], whereas the other five-membered ring deviates markedly from planarity [torsion angles: -15.3 (4), 14.3 (4), -7.8 (4), -1.5 (4), 10.7 (4)°]. The central C-C bond length is 1.488 (4) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801021080/bt6094sup1.cif
Contains datablocks I, ccd1628

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801021080/bt6094Isup2.hkl
Contains datablock I

CCDC reference: 180536

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.006 Å
  • R factor = 0.036
  • wR factor = 0.076
  • Data-to-parameter ratio = 7.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

REFLT_03 From the CIF: _diffrn_reflns_theta_max 25.34 From the CIF: _reflns_number_total 1285 Count of symmetry unique reflns 1329 Completeness (_total/calc) 96.69% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.

Comment top

The title compound, (I), represents the most stable dimer of indene obtained by the cationic dimerization through the reaction of the 2,3-dihydro-1H-inden-1-yl carbenium ion with 1H-indene at position 2. Compound (I) was described in the literature by Moglioni et al. (1998) and Noland et al. (1979), but a crystal structure has not been reported previously. It is the constituent of many pyrolysis oils and its characterization for environmental analysis. It also represents a useful model substance for MS and NMR analysis, and structural data are important for the understanding of some fine details of MS and NMR spectra.

Experimental top

The general procedure was the one described by Dansi & Pasini (1951). 10 g of indene (>99.0% purity) and 40 ml 48% H2SO4, as a two-phase mixture, were refluxed (oil-bath temperature 398–403 K) with vigorous stirring for 8 h. After cooling to room temperature, 100 ml cyclohexane were added. The reaction mixture was neutralized with NaHCO3 (5%), washed with water and dried over Na2SO4. After evaporating the cyclohexane, 8.7 g of yellow viscous oil were obtained. It contained more than 85% of (I), which was isolated by crystallization from propan-2-ol.

Refinement top

H atoms were placed in calculated positions with Uiso constrained to be 1.2 times Ueq of the carrier atom. Friedel opposites were merged and no attempts were made to refine the absolute configuration.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97, PARST95 (Nardelli, 1995) and PLATON (Spek, 2001).

Figures top
[Figure 1] Fig. 1. View of the title compound (XP, Sheldrick, 1991) showing the labelling of all non-H atoms. Displacement ellipsoids are shown at the 30% probability levels. H atoms are drawn as circles of arbitrary radii.
(I) top
Crystal data top
C18H16Dx = 1.173 Mg m3
Mr = 232.31Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Fdd2Cell parameters from 10913 reflections
a = 20.2837 (8) Åθ = 3.5–25.3°
b = 42.098 (2) ŵ = 0.07 mm1
c = 6.1644 (2) ÅT = 293 K
V = 5263.8 (4) Å3Needle, colourless
Z = 160.50 × 0.05 × 0.02 mm
F(000) = 1984
Data collection top
Nonius KappaCCD
diffractometer
565 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.041
Graphite monochromatorθmax = 25.3°, θmin = 3.5°
Detector resolution: 10 vertical, 18 horizontal pixels mm-1h = 2323
319 frames via ω–rotation (Δω=1°) with 3 sets at different κ–angles and two times 150 s per frame scansk = 5050
10913 measured reflectionsl = 77
1285 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)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.076H-atom parameters constrained
S = 0.82 w = 1/[σ2(Fo2) + (0.0275P)2]
where P = (Fo2 + 2Fc2)/3
1285 reflections(Δ/σ)max < 0.001
163 parametersΔρmax = 0.10 e Å3
1 restraintΔρmin = 0.10 e Å3
Crystal data top
C18H16V = 5263.8 (4) Å3
Mr = 232.31Z = 16
Orthorhombic, Fdd2Mo Kα radiation
a = 20.2837 (8) ŵ = 0.07 mm1
b = 42.098 (2) ÅT = 293 K
c = 6.1644 (2) Å0.50 × 0.05 × 0.02 mm
Data collection top
Nonius KappaCCD
diffractometer
565 reflections with I > 2σ(I)
10913 measured reflectionsRint = 0.041
1285 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0361 restraint
wR(F2) = 0.076H-atom parameters constrained
S = 0.82Δρmax = 0.10 e Å3
1285 reflectionsΔρmin = 0.10 e Å3
163 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
xyzUiso*/Ueq
C10.3605 (2)0.13592 (11)0.2578 (7)0.1197 (15)
H1A0.34880.13360.40960.144*
H1B0.40390.14550.24820.144*
C20.35917 (18)0.10474 (10)0.1460 (7)0.1097 (14)
H2A0.40380.09730.12080.132*
H2B0.33630.08920.23430.132*
C30.32261 (16)0.10933 (9)0.0740 (6)0.0755 (10)
H3A0.35550.11110.18980.091*
C40.29031 (17)0.14105 (9)0.0450 (6)0.0687 (10)
C50.24549 (19)0.15543 (10)0.1801 (7)0.0983 (13)
H5A0.23190.14530.30660.118*
C60.2208 (2)0.18492 (13)0.1270 (11)0.1176 (18)
H6A0.19100.19490.21910.141*
C70.2401 (3)0.19964 (11)0.0613 (14)0.129 (2)
H7A0.22290.21930.09950.155*
C80.2850 (3)0.18486 (13)0.1912 (9)0.1163 (17)
H8A0.29870.19490.31790.140*
C90.31012 (19)0.15584 (11)0.1401 (7)0.0806 (11)
C110.21865 (17)0.07384 (8)0.0097 (5)0.0766 (11)
H11A0.23310.06710.15240.092*
H11B0.18820.09140.02580.092*
C120.27638 (16)0.08309 (8)0.1289 (6)0.0667 (10)
C130.27698 (17)0.06421 (8)0.3037 (6)0.0717 (10)
H13A0.30820.06540.41400.086*
C140.22312 (18)0.04180 (8)0.2995 (6)0.0642 (9)
C150.2060 (2)0.01784 (10)0.4429 (6)0.0830 (11)
H15A0.22990.01460.56970.100*
C160.1529 (3)0.00105 (10)0.3929 (8)0.1007 (15)
H16A0.14130.01750.48640.121*
C170.1168 (2)0.00378 (11)0.2090 (11)0.1064 (15)
H17A0.08080.00920.17920.128*
C180.1334 (2)0.02803 (10)0.0660 (7)0.0911 (12)
H180.10860.03150.05860.109*
C190.18719 (19)0.04683 (8)0.1118 (6)0.0712 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.161 (4)0.116 (4)0.082 (3)0.001 (3)0.036 (3)0.001 (3)
C20.114 (3)0.099 (3)0.117 (4)0.003 (3)0.053 (3)0.010 (3)
C30.077 (3)0.070 (3)0.079 (2)0.004 (2)0.005 (2)0.002 (2)
C40.068 (2)0.064 (3)0.074 (3)0.010 (2)0.011 (2)0.003 (3)
C50.094 (3)0.078 (3)0.122 (4)0.007 (3)0.037 (3)0.011 (3)
C60.082 (3)0.067 (4)0.203 (6)0.001 (3)0.008 (4)0.034 (4)
C70.105 (4)0.063 (4)0.219 (7)0.003 (3)0.068 (5)0.012 (5)
C80.129 (4)0.099 (4)0.121 (4)0.015 (3)0.026 (4)0.023 (4)
C90.093 (3)0.069 (3)0.080 (3)0.000 (2)0.006 (2)0.006 (3)
C110.092 (3)0.072 (3)0.066 (3)0.011 (2)0.005 (2)0.000 (2)
C120.067 (2)0.067 (2)0.067 (3)0.006 (2)0.004 (2)0.007 (2)
C130.079 (3)0.073 (3)0.064 (2)0.010 (2)0.009 (2)0.003 (3)
C140.078 (2)0.055 (3)0.059 (2)0.009 (2)0.001 (2)0.001 (2)
C150.097 (3)0.070 (3)0.082 (3)0.011 (2)0.000 (3)0.003 (3)
C160.110 (4)0.069 (3)0.123 (4)0.002 (3)0.026 (4)0.004 (3)
C170.092 (3)0.076 (4)0.150 (5)0.013 (3)0.006 (4)0.025 (3)
C180.083 (3)0.084 (3)0.106 (3)0.005 (2)0.019 (2)0.017 (3)
C190.077 (3)0.065 (3)0.071 (3)0.003 (2)0.004 (2)0.010 (2)
Geometric parameters (Å, º) top
C1—C21.483 (5)C8—H8A0.9300
C1—C91.507 (5)C11—C121.501 (4)
C1—H1A0.9700C11—C191.503 (4)
C1—H1B0.9700C11—H11A0.9700
C2—C31.558 (5)C11—H11B0.9700
C2—H2A0.9700C12—C131.339 (4)
C2—H2B0.9700C13—C141.444 (4)
C3—C121.488 (4)C13—H13A0.9300
C3—C41.498 (4)C14—C191.384 (4)
C3—H3A0.9800C14—C151.385 (4)
C4—C91.361 (4)C15—C161.374 (5)
C4—C51.374 (4)C15—H15A0.9300
C5—C61.378 (5)C16—C171.365 (5)
C5—H5A0.9300C16—H16A0.9300
C6—C71.373 (7)C17—C181.390 (6)
C6—H6A0.9300C17—H17A0.9300
C7—C81.362 (7)C18—C191.378 (5)
C7—H7A0.9300C18—H180.9300
C8—C91.361 (5)
C2—C1—C9104.9 (3)C4—C9—C8119.6 (4)
C2—C1—H1A110.8C4—C9—C1110.4 (4)
C9—C1—H1A110.8C8—C9—C1129.9 (5)
C2—C1—H1B110.8C12—C11—C19104.1 (3)
C9—C1—H1B110.8C12—C11—H11A110.9
H1A—C1—H1B108.8C19—C11—H11A110.9
C1—C2—C3107.7 (3)C12—C11—H11B110.9
C1—C2—H2A110.2C19—C11—H11B110.9
C3—C2—H2A110.2H11A—C11—H11B109.0
C1—C2—H2B110.2C13—C12—C3128.2 (3)
C3—C2—H2B110.2C13—C12—C11108.1 (3)
H2A—C2—H2B108.5C3—C12—C11123.7 (3)
C12—C3—C4114.4 (3)C12—C13—C14111.5 (3)
C12—C3—C2113.9 (3)C12—C13—H13A124.2
C4—C3—C2102.4 (3)C14—C13—H13A124.2
C12—C3—H3A108.6C19—C14—C15120.9 (4)
C4—C3—H3A108.6C19—C14—C13108.3 (3)
C2—C3—H3A108.6C15—C14—C13130.8 (4)
C9—C4—C5120.1 (4)C16—C15—C14118.3 (4)
C9—C4—C3112.3 (3)C16—C15—H15A120.8
C5—C4—C3127.6 (4)C14—C15—H15A120.8
C4—C5—C6119.6 (4)C17—C16—C15121.4 (4)
C4—C5—H5A120.2C17—C16—H16A119.3
C6—C5—H5A120.2C15—C16—H16A119.3
C7—C6—C5120.3 (5)C16—C17—C18120.4 (4)
C7—C6—H6A119.9C16—C17—H17A119.8
C5—C6—H6A119.9C18—C17—H17A119.8
C8—C7—C6118.8 (5)C19—C18—C17119.0 (4)
C8—C7—H7A120.6C19—C18—H18120.5
C6—C7—H7A120.6C17—C18—H18120.5
C7—C8—C9121.6 (5)C18—C19—C14120.0 (4)
C7—C8—H8A119.2C18—C19—C11132.0 (4)
C9—C8—H8A119.2C14—C19—C11108.0 (3)
C9—C1—C2—C315.3 (4)C4—C3—C12—C1157.5 (5)
C1—C2—C3—C12138.4 (4)C2—C3—C12—C1159.9 (4)
C1—C2—C3—C414.3 (4)C19—C11—C12—C130.4 (3)
C12—C3—C4—C9131.6 (3)C19—C11—C12—C3179.6 (3)
C2—C3—C4—C97.8 (4)C3—C12—C13—C14179.2 (3)
C12—C3—C4—C548.3 (5)C11—C12—C13—C140.1 (4)
C2—C3—C4—C5172.1 (3)C12—C13—C14—C190.3 (4)
C9—C4—C5—C60.1 (5)C12—C13—C14—C15178.5 (3)
C3—C4—C5—C6180.0 (4)C19—C14—C15—C160.7 (5)
C4—C5—C6—C71.0 (7)C13—C14—C15—C16177.3 (4)
C5—C6—C7—C81.4 (7)C14—C15—C16—C171.1 (6)
C6—C7—C8—C91.0 (8)C15—C16—C17—C180.4 (6)
C5—C4—C9—C80.4 (5)C16—C17—C18—C190.7 (6)
C3—C4—C9—C8179.6 (3)C17—C18—C19—C141.1 (5)
C5—C4—C9—C1178.5 (3)C17—C18—C19—C11178.1 (3)
C3—C4—C9—C11.5 (4)C15—C14—C19—C180.4 (5)
C7—C8—C9—C40.0 (6)C13—C14—C19—C18178.8 (3)
C7—C8—C9—C1178.8 (4)C15—C14—C19—C11178.9 (3)
C2—C1—C9—C410.7 (4)C13—C14—C19—C110.6 (3)
C2—C1—C9—C8170.5 (4)C12—C11—C19—C18178.7 (3)
C4—C3—C12—C13121.5 (4)C12—C11—C19—C140.6 (3)
C2—C3—C12—C13121.2 (4)

Experimental details

Crystal data
Chemical formulaC18H16
Mr232.31
Crystal system, space groupOrthorhombic, Fdd2
Temperature (K)293
a, b, c (Å)20.2837 (8), 42.098 (2), 6.1644 (2)
V3)5263.8 (4)
Z16
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.50 × 0.05 × 0.02
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
10913, 1285, 565
Rint0.041
(sin θ/λ)max1)0.602
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.076, 0.82
No. of reflections1285
No. of parameters163
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.10, 0.10

Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), DENZO and SCALEPACK, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL-Plus (Sheldrick, 1991), SHELXL97, PARST95 (Nardelli, 1995) and PLATON (Spek, 2001).

 

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