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

Santos, A.C.; Ramos Silva, M.; Monsanto, P.V.; Matos Beja, A.; Sobral, A.J.F.N.

doi:10.1107/S1600536809021965

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 7| July 2009| Page o1594

doi:10.1107/S1600536809021965

Open

access

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

Ana C. Santos,^a Manuela Ramos Silva,^b ^* Paula V. Monsanto,^c Ana Matos Beja ^b and Abilio J. F. N. Sobral ^a

^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 ); Chane-Ching et al. (1998 ); Just et al. (1999 ). For related structures, see: Ramos Silva et al. (2002 , 2005 , 2008 ).

Experimental

Crystal data

C₁₈H₂₈N₂
M_r = 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 ) T_min = 0.881, T_max = 0.997
12290 measured reflections
3799 independent reflections
2110 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.053
wR(F²) = 0.180
S = 1.03
3799 reflections
93 parameters
H-atom parameters constrained
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	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 ); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; 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.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809021965/su2118sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809021965/su2118Isup2.hkl

checkCIF report

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 C_i 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).

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

	Fig. 1. ORTEPII (Johnson, 1976) plot of the title compound. Displacement ellipsoids are drawn at the 50% probabilty level.
	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

C₁₈H₂₈N₂	F(000) = 300
M_r = 272.42	D_x = 1.076 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.7608 (3) Å	Cell parameters from 2568 reflections
b = 6.4767 (3) Å	θ = 2.6–30.6°
c = 16.7738 (7) Å	µ = 0.06 mm⁻¹
β = 94.309 (3)°	T = 293 K
V = 840.74 (6) Å³	Needle, yellow
Z = 2	0.35 × 0.10 × 0.06 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	3799 independent reflections
Radiation source: fine-focus sealed tube	2110 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
ϕ and ω scans	θ_max = 35.4°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = −12→12
T_min = 0.881, T_max = 0.997	k = −10→10
12290 measured reflections	l = −27→26

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.180	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.084P)² + 0.0541P] where P = (F_o² + 2F_c²)/3
3799 reflections	(Δ/σ)_max < 0.001
93 parameters	Δρ_max = 0.33 e Å⁻³
0 restraints	Δρ_min = −0.24 e Å⁻³

Crystal data top

C₁₈H₂₈N₂	V = 840.74 (6) Å³
M_r = 272.42	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 7.7608 (3) Å	µ = 0.06 mm⁻¹
b = 6.4767 (3) Å	T = 293 K
c = 16.7738 (7) Å	0.35 × 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)
T_min = 0.881, T_max = 0.997	R_int = 0.025
12290 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	0 restraints
wR(F²) = 0.180	H-atom parameters constrained
S = 1.03	Δρ_max = 0.33 e Å⁻³
3799 reflections	Δρ_min = −0.24 e Å⁻³
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

	x	y	z	U_iso*/U_eq
N1	0.36575 (10)	0.90724 (13)	0.13870 (5)	0.0405 (2)
C2	0.15288 (14)	0.71268 (16)	0.04807 (6)	0.0461 (2)
H2A	0.2278	0.7239	0.0045	0.055*
H2B	0.0732	0.8283	0.0444	0.055*
C1	0.05154 (13)	0.51178 (16)	0.03991 (6)	0.0438 (2)
H1A	0.1315	0.3970	0.0471	0.053*
H1B	−0.0269	0.5048	0.0822	0.053*
C7	0.32211 (13)	1.07945 (16)	0.18158 (6)	0.0444 (2)
C3	0.26078 (15)	0.72241 (17)	0.12703 (6)	0.0490 (3)
H3A	0.1842	0.7133	0.1700	0.059*
H3B	0.3363	0.6029	0.1310	0.059*
C4	0.53191 (13)	0.92871 (18)	0.11692 (6)	0.0473 (3)
C6	0.46125 (16)	1.20827 (17)	0.18618 (7)	0.0513 (3)
H6	0.4681	1.3360	0.2116	0.062*
C5	0.59257 (15)	1.1140 (2)	0.14579 (7)	0.0547 (3)
H5	0.7017	1.1684	0.1398	0.066*
C8	0.15291 (18)	1.1023 (3)	0.21603 (10)	0.0741 (4)
H8A	0.1485	1.2332	0.2427	0.111*
H8B	0.1386	0.9932	0.2537	0.111*
H8C	0.0620	1.0952	0.1740	0.111*
C9	0.61868 (19)	0.7690 (3)	0.07002 (9)	0.0770 (5)
H9A	0.7339	0.8135	0.0615	0.116*
H9B	0.5546	0.7496	0.0194	0.116*
H9C	0.6235	0.6411	0.0990	0.116*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0412 (4)	0.0383 (4)	0.0410 (4)	0.0004 (3)	−0.0041 (3)	−0.0022 (3)
C2	0.0477 (5)	0.0449 (6)	0.0443 (5)	−0.0050 (4)	−0.0057 (4)	0.0003 (4)
C1	0.0452 (5)	0.0434 (5)	0.0420 (5)	−0.0030 (4)	−0.0018 (4)	−0.0029 (4)
C7	0.0486 (5)	0.0423 (5)	0.0413 (5)	0.0083 (4)	−0.0031 (4)	−0.0014 (4)
C3	0.0554 (6)	0.0420 (5)	0.0475 (6)	−0.0075 (4)	−0.0093 (4)	0.0022 (4)
C4	0.0420 (5)	0.0562 (6)	0.0430 (5)	0.0043 (4)	−0.0008 (4)	0.0002 (4)
C6	0.0670 (7)	0.0383 (5)	0.0463 (6)	−0.0021 (5)	−0.0113 (5)	−0.0001 (4)
C5	0.0489 (6)	0.0623 (7)	0.0514 (6)	−0.0127 (5)	−0.0062 (4)	0.0088 (5)
C8	0.0626 (8)	0.0870 (11)	0.0739 (9)	0.0184 (7)	0.0119 (6)	−0.0092 (8)
C9	0.0652 (8)	0.0941 (11)	0.0722 (9)	0.0247 (8)	0.0077 (7)	−0.0169 (8)

Geometric parameters (Å, º) top

N1—C4	1.3735 (13)	C3—H3B	0.9700
N1—C7	1.3830 (13)	C4—C5	1.3647 (17)
N1—C3	1.4529 (13)	C4—C9	1.4904 (17)
C2—C3	1.5141 (14)	C6—C5	1.4049 (18)
C2—C1	1.5212 (14)	C6—H6	0.9300
C2—H2A	0.9700	C5—H5	0.9300
C2—H2B	0.9700	C8—H8A	0.9600
C1—C1ⁱ	1.5149 (18)	C8—H8B	0.9600
C1—H1A	0.9700	C8—H8C	0.9600
C1—H1B	0.9700	C9—H9A	0.9600
C7—C6	1.3622 (16)	C9—H9B	0.9600
C7—C8	1.4812 (17)	C9—H9C	0.9600
C3—H3A	0.9700

C4—N1—C7	109.16 (9)	H3A—C3—H3B	107.5
C4—N1—C3	125.15 (9)	C5—C4—N1	107.48 (10)
C7—N1—C3	125.29 (9)	C5—C4—C9	129.80 (12)
C3—C2—C1	111.26 (8)	N1—C4—C9	122.72 (11)
C3—C2—H2A	109.4	C7—C6—C5	107.90 (10)
C1—C2—H2A	109.4	C7—C6—H6	126.1
C3—C2—H2B	109.4	C5—C6—H6	126.1
C1—C2—H2B	109.4	C4—C5—C6	108.05 (10)
H2A—C2—H2B	108.0	C4—C5—H5	126.0
C1ⁱ—C1—C2	113.63 (11)	C6—C5—H5	126.0
C1ⁱ—C1—H1A	108.8	C7—C8—H8A	109.5
C2—C1—H1A	108.8	C7—C8—H8B	109.5
C1ⁱ—C1—H1B	108.8	H8A—C8—H8B	109.5
C2—C1—H1B	108.8	C7—C8—H8C	109.5
H1A—C1—H1B	107.7	H8A—C8—H8C	109.5
C6—C7—N1	107.41 (10)	H8B—C8—H8C	109.5
C6—C7—C8	129.72 (11)	C4—C9—H9A	109.5
N1—C7—C8	122.84 (11)	C4—C9—H9B	109.5
N1—C3—C2	114.82 (8)	H9A—C9—H9B	109.5
N1—C3—H3A	108.6	C4—C9—H9C	109.5
C2—C3—H3A	108.6	H9A—C9—H9C	109.5
N1—C3—H3B	108.6	H9B—C9—H9C	109.5
C2—C3—H3B	108.6

C3—C2—C1—C1ⁱ	−176.89 (11)	C3—N1—C4—C5	−173.23 (9)
C4—N1—C7—C6	0.20 (11)	C7—N1—C4—C9	179.88 (11)
C3—N1—C7—C6	173.26 (9)	C3—N1—C4—C9	6.81 (16)
C4—N1—C7—C8	−178.14 (11)	N1—C7—C6—C5	−0.16 (12)
C3—N1—C7—C8	−5.08 (16)	C8—C7—C6—C5	178.02 (12)
C4—N1—C3—C2	−89.88 (13)	N1—C4—C5—C6	0.06 (12)
C7—N1—C3—C2	98.15 (12)	C9—C4—C5—C6	−179.98 (12)
C1—C2—C3—N1	178.31 (9)	C7—C6—C5—C4	0.06 (13)
C7—N1—C4—C5	−0.16 (12)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···Cg1ⁱⁱ	0.93	2.67	3.4918 (13)	148

Symmetry code: (ii) −x+1, y+1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₈N₂
M_r	272.42
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	7.7608 (3), 6.4767 (3), 16.7738 (7)
β (°)	94.309 (3)
V (Å³)	840.74 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.06
Crystal size (mm)	0.35 × 0.10 × 0.06

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2000)
T_min, T_max	0.881, 0.997
No. of measured, independent and observed [I > 2σ(I)] reflections	12290, 3799, 2110
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.816

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.180, 1.03
No. of reflections	3799
No. of parameters	93
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	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···A	D—H	H···A	D···A	D—H···A
C6—H6···Cg1ⁱ	0.93	2.67	3.4918 (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

Bruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
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. Web of Science CrossRef CAS Google Scholar
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA. Google Scholar
Just, 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
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. Google Scholar
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. Web of Science CSD CrossRef IUCr Journals Google Scholar
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. Google Scholar
Sheldrick, G. M. (2000). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zotti, G., Schiavon, G., Zecchin, S., Berlin, A., Pagani, G. & Canavesi, A. (1997). Langmuir, 13, 2694–2698. CrossRef CAS Web of Science Google Scholar