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The molecule of the title compound, C22H22N2, has a center of symmetry, and two bulky indolizinyl groups are situated on opposite sides of the C=C double bond, resulting in an E configuration. The two indolizinyl groups and the C=C double bond are in the same plane, forming a fully extended conjugated system. There are π–π stacking interactions between neighboring mol­ecules related by a center of symmetry.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803013795/ob6262sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803013795/ob6262Isup2.hkl
Contains datablock I

CCDC reference: 217611

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.050
  • wR factor = 0.106
  • Data-to-parameter ratio = 15.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Comment top

Thiocarbonyl compounds are much more reactive than the corresponding carbonyl compounds because of the lower electronegativity and the special electronic structure of the S atom as compared with the O atom. Thiocarbonyl compounds can take part in diversified chemical reactions. As a result, they have found wide-ranging applications in the synthesis of cyclic compounds (Vedejs et al., 1998), natural products (Vedejs et al., 1998), organic conductors and superconductors (Parg et al., 1994). Many practical applications of thiocarbonyl compounds have also been reported (Mastalerz et al., 2001). The majority of thiocarbonyl chemistry are based on investigation with thioketones as substrate because simple thioaldehydes are unstable. However, resonance-stabilized thioaldehydes, such as 1,2-dimethyl-3-thioformylindolizine are quite stable even on long standing. We have investigated the reactions of the indolizinethioaldehyde with tributylphosphine, and found that the conversion of the indolizinethioaldehyde into the title compound, (I), is stereoselective (see Scheme). The structure of (I) is similar to that of trans-stilbene. It is expected that (I) may have great potential as antitumor agent.

The title molecule is centrosymmetric (Fig. 1 and Table 1). The two bulky indolizinyl groups are situated on opposite sides of the CC double bond, resulting in an E configuration. The indolizine rings are coplanar with the CC double bond, forming a large extended conjugate system. In the crystal structure, two neighbouring molecules related by center of symmetry show ππ-stacking interactions, with vertical distances of 3.269 (6) Å between the centers of the six-membered rings.

Experimental top

A solution of 1,2-dimethyl-3-thioformylindolizine (0.28 g, 1.5 mmol) in anhydrous THF (8 ml) was stirred at room temperature and after the air had been replaced by N2 gas, tributylphosphine (1.1 g, 5.4 mmol) was added. The reaction mixture was maintained under reflux for 14 h until all the 1,2-dimethyl-3-thioformylindolizine disappeared (monitored by TLC). The solvent was removed in vacuo, the mixture was cooled and the title compound, (I), was collected by filtration and washed with petroleum ether. Yellow single crystals of (I) suitable for X-ray crystallographic analysis were obtained by recrystallization from petroleum ether.

Refinement top

The positions of all H atoms were fixed geometrically and refined as riding. The distances to H atoms were in the range 0.93–0.96 Å.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. The packing diagram of (I), viewed down the a axis.
(E)-1,2-bis(1,2-dimethyl-3-indolizinyl)ethene top
Crystal data top
C22H22N2F(000) = 336
Mr = 314.42Dx = 1.251 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1482 reflections
a = 8.253 (2) Åθ = 2.5–24.4°
b = 5.435 (1) ŵ = 0.07 mm1
c = 19.056 (4) ÅT = 293 K
β = 102.51 (1)°Block, yellow
V = 834.5 (3) Å30.3 × 0.2 × 0.2 mm
Z = 2
Data collection top
Bruker Smart APEX CCD area-detector
diffractometer
1105 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.060
Graphite monochromatorθmax = 25.5°, θmin = 2.2°
ϕ and ω scansh = 810
4170 measured reflectionsk = 66
1530 independent reflectionsl = 2320
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)] = 0.050Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.106H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.02P)2 + 0.25P]
where P = (Fo2 + 2Fc2)/3
1530 reflections(Δ/σ)max < 0.001
99 parametersΔρmax = 0.27 e Å3
0 restraintsΔρmin = 0.31 e Å3
Crystal data top
C22H22N2V = 834.5 (3) Å3
Mr = 314.42Z = 2
Monoclinic, P21/cMo Kα radiation
a = 8.253 (2) ŵ = 0.07 mm1
b = 5.435 (1) ÅT = 293 K
c = 19.056 (4) Å0.3 × 0.2 × 0.2 mm
β = 102.51 (1)°
Data collection top
Bruker Smart APEX CCD area-detector
diffractometer
1105 reflections with I > 2σ(I)
4170 measured reflectionsRint = 0.060
1530 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0500 restraints
wR(F2) = 0.106H-atom parameters constrained
S = 1.02Δρmax = 0.27 e Å3
1530 reflectionsΔρmin = 0.31 e Å3
99 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
C10.1852 (2)0.3177 (3)0.34019 (9)0.0466 (3)
C20.0733 (2)0.2805 (3)0.38456 (9)0.0457 (4)
C30.1295 (2)0.0877 (4)0.43166 (10)0.0513 (4)
C50.3784 (2)0.1860 (4)0.44393 (11)0.0590 (6)
H50.35330.28070.48080.071*
C60.5148 (3)0.2342 (4)0.41966 (12)0.0662 (6)
H60.58250.36500.43920.079*
C70.5584 (3)0.0910 (4)0.36505 (11)0.0655 (6)
H70.65580.12330.34970.079*
C80.4571 (2)0.0944 (4)0.33500 (10)0.0556 (5)
H80.48400.18730.29820.067*
C90.3113 (2)0.1472 (4)0.35912 (9)0.0466 (3)
C100.0679 (2)0.0263 (4)0.48879 (10)0.0513 (4)
H100.13240.15330.51300.062*
C110.0830 (2)0.4273 (4)0.38055 (11)0.0609 (6)
H11A0.09240.54880.34330.091*
H11B0.07910.50740.42580.091*
H11C0.17720.31940.37000.091*
C120.1745 (3)0.5079 (4)0.28209 (10)0.0624 (6)
H12A0.10560.44730.23830.094*
H12B0.28370.54150.27460.094*
H12C0.12730.65640.29630.094*
N40.27450 (18)0.0029 (3)0.41486 (7)0.0467 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0442 (7)0.0541 (8)0.0423 (7)0.0051 (6)0.0116 (6)0.0003 (6)
C20.0379 (9)0.0517 (11)0.0477 (10)0.0035 (9)0.0098 (8)0.0049 (9)
C30.0437 (7)0.0601 (9)0.0531 (8)0.0002 (7)0.0175 (6)0.0018 (7)
C50.0575 (12)0.0663 (14)0.0560 (11)0.0070 (11)0.0187 (10)0.0114 (10)
C60.0564 (12)0.0713 (15)0.0745 (14)0.0175 (12)0.0223 (11)0.0098 (12)
C70.0455 (11)0.0825 (16)0.0734 (14)0.0055 (11)0.0239 (11)0.0019 (12)
C80.0510 (11)0.0674 (14)0.0535 (11)0.0042 (11)0.0229 (10)0.0002 (10)
C90.0442 (7)0.0541 (8)0.0423 (7)0.0051 (6)0.0116 (6)0.0003 (6)
C100.0437 (7)0.0601 (9)0.0531 (8)0.0002 (7)0.0175 (6)0.0018 (7)
C110.0534 (11)0.0618 (13)0.0701 (13)0.0112 (11)0.0193 (10)0.0075 (11)
C120.0626 (13)0.0663 (14)0.0601 (12)0.0006 (11)0.0171 (10)0.0118 (11)
N40.0446 (8)0.0530 (9)0.0456 (8)0.0010 (8)0.0165 (7)0.0029 (7)
Geometric parameters (Å, º) top
C1—C91.382 (3)C7—H70.9300
C1—C21.395 (2)C8—C91.407 (2)
C1—C121.503 (2)C8—H80.9300
C2—C31.392 (3)C9—N41.405 (2)
C2—C111.505 (3)C10—C10i1.315 (3)
C3—N41.383 (2)C10—H100.9300
C3—C101.438 (2)C11—H11A0.9600
C5—C61.333 (3)C11—H11B0.9600
C5—N41.375 (2)C11—H11C0.9600
C5—H50.9300C12—H12A0.9600
C6—C71.407 (3)C12—H12B0.9600
C6—H60.9300C12—H12C0.9600
C7—C81.354 (3)
C9—C1—C2107.73 (16)C1—C9—N4107.31 (15)
C9—C1—C12125.05 (17)C1—C9—C8134.45 (18)
C2—C1—C12127.22 (17)N4—C9—C8118.24 (17)
C3—C2—C1109.15 (16)C10i—C10—C3128.2 (3)
C3—C2—C11126.44 (16)C10i—C10—H10115.9
C1—C2—C11124.41 (17)C3—C10—H10115.9
N4—C3—C2106.60 (15)C2—C11—H11A109.5
N4—C3—C10119.80 (17)C2—C11—H11B109.5
C2—C3—C10133.60 (17)H11A—C11—H11B109.5
C6—C5—N4120.49 (19)C2—C11—H11C109.5
C6—C5—H5119.8H11A—C11—H11C109.5
N4—C5—H5119.8H11B—C11—H11C109.5
C5—C6—C7121.2 (2)C1—C12—H12A109.5
C5—C6—H6119.4C1—C12—H12B109.5
C7—C6—H6119.4H12A—C12—H12B109.5
C8—C7—C6119.42 (18)C1—C12—H12C109.5
C8—C7—H7120.3H12A—C12—H12C109.5
C6—C7—H7120.3H12B—C12—H12C109.5
C7—C8—C9120.44 (19)C5—N4—C3130.62 (16)
C7—C8—H8119.8C5—N4—C9120.19 (15)
C9—C8—H8119.8C3—N4—C9109.18 (15)
C9—C1—C2—C30.4 (2)C7—C8—C9—C1179.7 (2)
C12—C1—C2—C3179.38 (18)C7—C8—C9—N40.0 (3)
C9—C1—C2—C11179.25 (18)N4—C3—C10—C10i178.7 (2)
C12—C1—C2—C111.0 (3)C2—C3—C10—C10i1.2 (4)
C1—C2—C3—N41.4 (2)C6—C5—N4—C3179.1 (2)
C11—C2—C3—N4178.23 (18)C6—C5—N4—C90.0 (3)
C1—C2—C3—C10178.8 (2)C2—C3—N4—C5178.94 (18)
C11—C2—C3—C101.6 (4)C10—C3—N4—C50.9 (3)
N4—C5—C6—C71.4 (3)C2—C3—N4—C91.9 (2)
C5—C6—C7—C82.1 (3)C10—C3—N4—C9178.28 (16)
C6—C7—C8—C91.4 (3)C1—C9—N4—C5179.05 (17)
C2—C1—C9—N40.8 (2)C8—C9—N4—C50.7 (3)
C12—C1—C9—N4179.47 (16)C1—C9—N4—C31.7 (2)
C2—C1—C9—C8179.5 (2)C8—C9—N4—C3178.57 (17)
C12—C1—C9—C80.2 (3)
Symmetry code: (i) x, y, z+1.

Experimental details

Crystal data
Chemical formulaC22H22N2
Mr314.42
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)8.253 (2), 5.435 (1), 19.056 (4)
β (°) 102.51 (1)
V3)834.5 (3)
Z2
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.3 × 0.2 × 0.2
Data collection
DiffractometerBruker Smart APEX CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4170, 1530, 1105
Rint0.060
(sin θ/λ)max1)0.605
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.050, 0.106, 1.02
No. of reflections1530
No. of parameters99
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.27, 0.31

Computer programs: SMART (Bruker, 2000), SMART, SAINT (Bruker, 2000), SHELXTL (Bruker, 2000), SHELXTL.

Selected geometric parameters (Å, º) top
C3—C101.438 (2)C10—C10i1.315 (3)
C10i—C10—C3128.2 (3)
C2—C3—C10—C10i1.2 (4)
Symmetry code: (i) x, y, z+1.
 

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