organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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2,2′,5,5′-Tetra­methyl-1,1′-(hexane-1,6-di­yl)di-1H-pyrrole

aChemistry Department, University of Coimbra, P-3004-516 Coimbra, Portugal, bCEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra, Portugal, and cForensic Toxicology Service, National Institute of Legal Medicine, Center Branch, 3000-213 Coimbra, Portugal
*Correspondence e-mail: manuela@pollux.fis.uc.pt

(Received 29 May 2009; accepted 9 June 2009; online 17 June 2009)

The mol­ecule of the title compound, C18H28N2, composed of two 2,5-dimethyl­pyrrole groups linked by a hexane chain, lies across a crystallographic inversion centre. The mean plane of the pyrrole ring is almost perpendicular to the mean plane of the central chain, making a dihedral angle of 89.09 (8)°. The crystal structure is stabilized by inter­molecular C—H⋯π inter­actions.

Related literature

For the use of chain spacers in conductive polymers, see: Zotti et al. (1997[Zotti, G., Schiavon, G., Zecchin, S., Berlin, A., Pagani, G. & Canavesi, A. (1997). Langmuir, 13, 2694-2698.]); Chane-Ching et al. (1998[Chane-Ching, K. I., Lacroix, J. C., Baudry, R., Jouini, M., Aeiyach, S., Lion, C. & Lacase, P. C. (1998). J. Electroanal. Chem. 453, 139-149.]); Just et al. (1999[Just, P. E., Chane-Ching, K. I., Lacroix, J. C. & Lacase, P. C. (1999). J. Electroanal. Chem. 479, 3-11.]). For related structures, see: Ramos Silva et al. (2002[Ramos Silva, M., Matos Beja, A., Paixão, J. A., Sobral, A. J. F. N., Lopes, S. H. & Rocha Gonsalves, A. M. d'A. (2002). Acta Cryst. C58, o572-o574.], 2005[Ramos Silva, M., Matos Beja, A., Paixão, J. A., Cabral, A. M. T. D. V., Barradas, F. I. F., Paliteiro, C. & Sobral, A. J. F. N. (2005). Z. Kristallogr. New Cryst. Struct. 220, 273-274.], 2008[Ramos Silva, R., Silva, J. A., Urbano, A. M., Santos, A. C., Sobral, A. J. F. N., Matos Beja, A. & Paixão, J. A. (2008). Z. Kristallogr. New Cryst. Struct. 223, 33-34.]).

[Scheme 1]

Experimental

Crystal data
  • C18H28N2

  • Mr = 272.42

  • Monoclinic, P 21 /c

  • a = 7.7608 (3) Å

  • b = 6.4767 (3) Å

  • c = 16.7738 (7) Å

  • β = 94.309 (3)°

  • V = 840.74 (6) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.06 mm−1

  • T = 293 K

  • 0.35 × 0.10 × 0.06 mm

Data collection
  • Bruker SMART APEX CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2000[Sheldrick, G. M. (2000). SADABS. University of Göttingen, Germany.]) Tmin = 0.881, Tmax = 0.997

  • 12290 measured reflections

  • 3799 independent reflections

  • 2110 reflections with I > 2σ(I)

  • Rint = 0.025

Refinement
  • R[F2 > 2σ(F2)] = 0.053

  • wR(F2) = 0.180

  • S = 1.03

  • 3799 reflections

  • 93 parameters

  • H-atom parameters constrained

  • Δρmax = 0.33 e Å−3

  • Δρmin = −0.24 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C6—H6⋯Cg1i 0.93 2.67 3.4918 (13) 148
Symmetry code: (i) [-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]. Cg1 is the centroid of the pyrrole ring.

Data collection: SMART (Bruker, 2003[Bruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2003[Bruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEPII (Johnson, 1976[Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Within our project of synthesizing new pyrrole derivatives for several technological purposes (Ramos Silva et al., 2002; Ramos Silva et al., 2005; Ramos Silva et al., 2008), we have prepared the title compound. This pyrrole derivative contains a long alkyl chain between two pyrrole rings. Such a configuration has proven useful in assembling conductive polymer layers (Zotti et al., 1997, Chane-Ching et al., 1998, Just et al., 1999).

The molecular structure of the title compound displays Ci symmetry (Fig. 1). The mean plane of the pyrrole ring is almost perpendicular to the mean plane of the central chain; the angle between their mean planes being 89.09 (8)°.

Due to the lack of donors/aceptors there are no conventional hydrogen bonds between the molecules. However, a C—H···π intermolecular interaction, involving the mean plane of the pyrrole ring (Cg1i: symmetry operation (i) -x+1, y+1/2, -z+1/2) and hydrogen H6 on atom C6 of the pyrrole ring, links the molecules and they assemble in a herringbone pattern (Fig. 2 and Table 1).

Related literature top

For the use of chain spacers in conductive polymers, see: Zotti et al. (1997); Chane-Ching et al. (1998); Just et al. (1999). For related structures, see: Ramos Silva et al. (2002, 2005, 2008). Cg1 is the centroid of the pyrrole ring.

Experimental top

0.250 g (2.15 mmol) of 1,4-phenylenedimethanamine and 0.5 ml (4.25 mmol) of hexane-2,5-dione were dissolved in 20 ml of tetrahydrofuran, under nitrogen atmosphere. 0.086 g (0.339 mmol) of iodine was added to the stirred solution at 40°C. The procedure was monitored by TLC. After completion of the reaction (1.5 h), 20 ml of CH2Cl2 were added to the mixture. The resulting mixture was washed successively with 5% Na2S2O3 solution (2 ml), NaHCO3 solution (2 ml) and brine (2 ml). The organic layer was then dried with anhydrous sodium sulfate and concentrated. The product was purified by flash chromatography on silica gel 60H FLUCKA/dichloromethane and recrystallized in cold dichloromethane, by slow solvent evaporation, yielding needle-shaped crystals; Yield 0.246 grams, corresponding to 0.9 mmol (%) = 21; GC MS (100 µmol/ml in CH2Cl2) m/z = 272; 1H-NMR (0.1 M in CDCl3, 499.428 MHz),σ 1.42 (m, 4H, Methylene), σ 1.62 (m, 4H, Methylene), σ 2.25 (s, 12H, Methyl), σ 3.75 (t, 4H, Methylene, J = 9.99 Hz), σ 5.81 (s, 4H, Pyrrole); 13C-NMR (0.1 M in CDCl3, 125.692 MHz).

Refinement top

H-atoms were positioned geometrically and refined using a riding model: C—H = 0.93 - 0.97 Å with Uiso(H) = kUeq(parent C-atom), where k = 1.2 for pyrrole and methylene H-atoms, and 1.5 for methyl H-atoms.

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. ORTEPII (Johnson, 1976) plot of the title compound. Displacement ellipsoids are drawn at the 50% probabilty level.
[Figure 2] Fig. 2. A view down the b axis of the crystal packing of the title compound, showing the C—H···π interactions as dashed lines (see Table 1 for details).
2,2',5,5'-Tetramethyl-1,1'-(hexane-1,6-diyl)di-1H-pyrrole top
Crystal data top
C18H28N2F(000) = 300
Mr = 272.42Dx = 1.076 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 7.7608 (3) ÅCell parameters from 2568 reflections
b = 6.4767 (3) Åθ = 2.6–30.6°
c = 16.7738 (7) ŵ = 0.06 mm1
β = 94.309 (3)°T = 293 K
V = 840.74 (6) Å3Needle, yellow
Z = 20.35 × 0.10 × 0.06 mm
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
3799 independent reflections
Radiation source: fine-focus sealed tube2110 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
ϕ and ω scansθmax = 35.4°, θmin = 2.4°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2000)
h = 1212
Tmin = 0.881, Tmax = 0.997k = 1010
12290 measured reflectionsl = 2726
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)] = 0.053Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.180H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.084P)2 + 0.0541P]
where P = (Fo2 + 2Fc2)/3
3799 reflections(Δ/σ)max < 0.001
93 parametersΔρmax = 0.33 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
C18H28N2V = 840.74 (6) Å3
Mr = 272.42Z = 2
Monoclinic, P21/cMo Kα radiation
a = 7.7608 (3) ŵ = 0.06 mm1
b = 6.4767 (3) ÅT = 293 K
c = 16.7738 (7) Å0.35 × 0.10 × 0.06 mm
β = 94.309 (3)°
Data collection top
Bruker SMART APEX CCD area-detector
diffractometer
3799 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2000)
2110 reflections with I > 2σ(I)
Tmin = 0.881, Tmax = 0.997Rint = 0.025
12290 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0530 restraints
wR(F2) = 0.180H-atom parameters constrained
S = 1.03Δρmax = 0.33 e Å3
3799 reflectionsΔρmin = 0.24 e Å3
93 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
N10.36575 (10)0.90724 (13)0.13870 (5)0.0405 (2)
C20.15288 (14)0.71268 (16)0.04807 (6)0.0461 (2)
H2A0.22780.72390.00450.055*
H2B0.07320.82830.04440.055*
C10.05154 (13)0.51178 (16)0.03991 (6)0.0438 (2)
H1A0.13150.39700.04710.053*
H1B0.02690.50480.08220.053*
C70.32211 (13)1.07945 (16)0.18158 (6)0.0444 (2)
C30.26078 (15)0.72241 (17)0.12703 (6)0.0490 (3)
H3A0.18420.71330.17000.059*
H3B0.33630.60290.13100.059*
C40.53191 (13)0.92871 (18)0.11692 (6)0.0473 (3)
C60.46125 (16)1.20827 (17)0.18618 (7)0.0513 (3)
H60.46811.33600.21160.062*
C50.59257 (15)1.1140 (2)0.14579 (7)0.0547 (3)
H50.70171.16840.13980.066*
C80.15291 (18)1.1023 (3)0.21603 (10)0.0741 (4)
H8A0.14851.23320.24270.111*
H8B0.13860.99320.25370.111*
H8C0.06201.09520.17400.111*
C90.61868 (19)0.7690 (3)0.07002 (9)0.0770 (5)
H9A0.73390.81350.06150.116*
H9B0.55460.74960.01940.116*
H9C0.62350.64110.09900.116*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0412 (4)0.0383 (4)0.0410 (4)0.0004 (3)0.0041 (3)0.0022 (3)
C20.0477 (5)0.0449 (6)0.0443 (5)0.0050 (4)0.0057 (4)0.0003 (4)
C10.0452 (5)0.0434 (5)0.0420 (5)0.0030 (4)0.0018 (4)0.0029 (4)
C70.0486 (5)0.0423 (5)0.0413 (5)0.0083 (4)0.0031 (4)0.0014 (4)
C30.0554 (6)0.0420 (5)0.0475 (6)0.0075 (4)0.0093 (4)0.0022 (4)
C40.0420 (5)0.0562 (6)0.0430 (5)0.0043 (4)0.0008 (4)0.0002 (4)
C60.0670 (7)0.0383 (5)0.0463 (6)0.0021 (5)0.0113 (5)0.0001 (4)
C50.0489 (6)0.0623 (7)0.0514 (6)0.0127 (5)0.0062 (4)0.0088 (5)
C80.0626 (8)0.0870 (11)0.0739 (9)0.0184 (7)0.0119 (6)0.0092 (8)
C90.0652 (8)0.0941 (11)0.0722 (9)0.0247 (8)0.0077 (7)0.0169 (8)
Geometric parameters (Å, º) top
N1—C41.3735 (13)C3—H3B0.9700
N1—C71.3830 (13)C4—C51.3647 (17)
N1—C31.4529 (13)C4—C91.4904 (17)
C2—C31.5141 (14)C6—C51.4049 (18)
C2—C11.5212 (14)C6—H60.9300
C2—H2A0.9700C5—H50.9300
C2—H2B0.9700C8—H8A0.9600
C1—C1i1.5149 (18)C8—H8B0.9600
C1—H1A0.9700C8—H8C0.9600
C1—H1B0.9700C9—H9A0.9600
C7—C61.3622 (16)C9—H9B0.9600
C7—C81.4812 (17)C9—H9C0.9600
C3—H3A0.9700
C4—N1—C7109.16 (9)H3A—C3—H3B107.5
C4—N1—C3125.15 (9)C5—C4—N1107.48 (10)
C7—N1—C3125.29 (9)C5—C4—C9129.80 (12)
C3—C2—C1111.26 (8)N1—C4—C9122.72 (11)
C3—C2—H2A109.4C7—C6—C5107.90 (10)
C1—C2—H2A109.4C7—C6—H6126.1
C3—C2—H2B109.4C5—C6—H6126.1
C1—C2—H2B109.4C4—C5—C6108.05 (10)
H2A—C2—H2B108.0C4—C5—H5126.0
C1i—C1—C2113.63 (11)C6—C5—H5126.0
C1i—C1—H1A108.8C7—C8—H8A109.5
C2—C1—H1A108.8C7—C8—H8B109.5
C1i—C1—H1B108.8H8A—C8—H8B109.5
C2—C1—H1B108.8C7—C8—H8C109.5
H1A—C1—H1B107.7H8A—C8—H8C109.5
C6—C7—N1107.41 (10)H8B—C8—H8C109.5
C6—C7—C8129.72 (11)C4—C9—H9A109.5
N1—C7—C8122.84 (11)C4—C9—H9B109.5
N1—C3—C2114.82 (8)H9A—C9—H9B109.5
N1—C3—H3A108.6C4—C9—H9C109.5
C2—C3—H3A108.6H9A—C9—H9C109.5
N1—C3—H3B108.6H9B—C9—H9C109.5
C2—C3—H3B108.6
C3—C2—C1—C1i176.89 (11)C3—N1—C4—C5173.23 (9)
C4—N1—C7—C60.20 (11)C7—N1—C4—C9179.88 (11)
C3—N1—C7—C6173.26 (9)C3—N1—C4—C96.81 (16)
C4—N1—C7—C8178.14 (11)N1—C7—C6—C50.16 (12)
C3—N1—C7—C85.08 (16)C8—C7—C6—C5178.02 (12)
C4—N1—C3—C289.88 (13)N1—C4—C5—C60.06 (12)
C7—N1—C3—C298.15 (12)C9—C4—C5—C6179.98 (12)
C1—C2—C3—N1178.31 (9)C7—C6—C5—C40.06 (13)
C7—N1—C4—C50.16 (12)
Symmetry code: (i) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C6—H6···Cg1ii0.932.673.4918 (13)148
Symmetry code: (ii) x+1, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC18H28N2
Mr272.42
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)7.7608 (3), 6.4767 (3), 16.7738 (7)
β (°) 94.309 (3)
V3)840.74 (6)
Z2
Radiation typeMo Kα
µ (mm1)0.06
Crystal size (mm)0.35 × 0.10 × 0.06
Data collection
DiffractometerBruker SMART APEX CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2000)
Tmin, Tmax0.881, 0.997
No. of measured, independent and
observed [I > 2σ(I)] reflections
12290, 3799, 2110
Rint0.025
(sin θ/λ)max1)0.816
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.180, 1.03
No. of reflections3799
No. of parameters93
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.33, 0.24

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPII (Johnson, 1976).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C6—H6···Cg1i0.932.673.4918 (13)148
Symmetry code: (i) x+1, y+1/2, z+1/2.
 

Acknowledgements

This work was supported by Fundação para a Ciência e a Tecnologia (FCT).

References

First citationBruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChane-Ching, K. I., Lacroix, J. C., Baudry, R., Jouini, M., Aeiyach, S., Lion, C. & Lacase, P. C. (1998). J. Electroanal. Chem. 453, 139–149.  Web of Science CrossRef CAS Google Scholar
First citationJohnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA.  Google Scholar
First citationJust, P. E., Chane-Ching, K. I., Lacroix, J. C. & Lacase, P. C. (1999). J. Electroanal. Chem. 479, 3–11.  Web of Science CrossRef CAS Google Scholar
First citationRamos Silva, M., Matos Beja, A., Paixão, J. A., Cabral, A. M. T. D. V., Barradas, F. I. F., Paliteiro, C. & Sobral, A. J. F. N. (2005). Z. Kristallogr. New Cryst. Struct. 220, 273–274.  Google Scholar
First citationRamos Silva, M., Matos Beja, A., Paixão, J. A., Sobral, A. J. F. N., Lopes, S. H. & Rocha Gonsalves, A. M. d'A. (2002). Acta Cryst. C58, o572–o574.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationRamos Silva, R., Silva, J. A., Urbano, A. M., Santos, A. C., Sobral, A. J. F. N., Matos Beja, A. & Paixão, J. A. (2008). Z. Kristallogr. New Cryst. Struct. 223, 33–34.  Google Scholar
First citationSheldrick, G. M. (2000). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationZotti, G., Schiavon, G., Zecchin, S., Berlin, A., Pagani, G. & Canavesi, A. (1997). Langmuir, 13, 2694–2698.  CrossRef CAS Web of Science Google Scholar

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