2,7-Bis(2-nitro­phen­yl)-9-octyl-9H-carbazole

Norma Wrobel; Dieter Schollmeyer; Heiner Detert

doi:10.1107/S1600536812012780

. 2012 Mar 31;68(Pt 4):o1249. doi: 10.1107/S1600536812012780

2,7-Bis(2-nitrophenyl)-9-octyl-9H-carbazole

Norma Wrobel ^a, Dieter Schollmeyer ^a, Heiner Detert ^a,^*

PMCID: PMC3344178 PMID: 22606181

Abstract

The title compound, C₃₂H₃₁N₃O₄, was obtained in a Suzuki coupling of carbazole diboronic acid and bromonitrobenzene. In the crystal, the molecule adopts a non-symmetric conformation. The carbazole ring system is approximately planar [maximum deviation from the least-squares plane = 0.039 (2) Å]. The planes of the carbazole unit and the benzene rings subtend dihedral angles of 48.42 (7) and 41.81 (6)°. The dihedral angles between the planes of the nitrophenyl rings and the nitro groups are 44.34 (19) and 61.64 (15)°. The crystal is built from two strands of parallel molecules with interdigitated octyl chains. These strands are symmetry related by a twofold screw axis.

Related literature

For Suzuki cross-couplings, see: Miyaura & Suzuki (1995 ▶). For the Cadogan reaction, see: Cadogan (1962 ▶). For indolocarbazoles, see: Nemkovich et al. (2009 ▶). For heteroanalogous carbazoles, see: Dassonneville et al. (2011 ▶); Letessier & Detert (2012 ▶). For the structures of aryl-substituted carbazoles and substituted p-terphenyls, see: Letessier et al. (2011 ▶); Jones et al. (2005 ▶); Moschel et al. (2011 ▶); Wrobel et al. (2012 ▶).

Experimental

Crystal data

C₃₂H₃₁N₃O₄
M _r = 521.60
Monoclinic,
a = 8.722 (2) Å
b = 7.987 (2) Å
c = 39.508 (11) Å
β = 95.044 (6)°
V = 2741.5 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 173 K
0.50 × 0.04 × 0.04 mm

Data collection

Bruker SMART APEXII diffractometer
15053 measured reflections
6525 independent reflections
2814 reflections with I > 2σ(I)
R _int = 0.099

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.137
S = 0.93
6525 reflections
353 parameters
H-atom parameters constrained
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812012780/rz2725sup1.cif

e-68-o1249-sup1.cif^{(37.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812012780/rz2725Isup2.hkl

e-68-o1249-Isup2.hkl^{(319.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812012780/rz2725Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors are grateful to A. Oehlhof and S. Mallon for preparative assistance.

supplementary crystallographic information

Comment

The title compound was prepared as an intermediate in a larger project on carbazoles and heteroanalogous carbazoles, see Dassonneville et al. (2011), Letessier et al. (2011), Letessier & Detert (2012). Indolocarbazoles (Nemkovich et al. 2009) are prepared by Cadogan reaction (Cadogan, 1962).

The molecule adopts a non-symmetric conformation with a nearly planar carbazole unit (maximum deviation from the least-squares plane = 0.039 (2) Å at C7). Attached to N9 is the octyl chain in an an all-trans conformation. The planes of the carbazole unit and the benzene rings subtend dihedral angles of 48.42 (7)° (ring C1–C9a and ring C18–C23) and 41.81 (6)° (ring C4b–C8a and ring C27–C32). Dihedral angles between the planes of the benzene rings and the nitro groups are 44.34 (19)° and 61.64 (35)°. Whereas the dihedral angles between the aromatic rings are comparable to those found in a o-nitrobiaryl with an additional o-substituent (Wrobel et al.., 2012), the dihedral angles between the planes of the niro groups and the adjacent benzene ring are even larger. Both nitro goups are oriented toward the N9 nitrogen atom of the carbazole. Two strands of parallel molecules with interdigitated octyl chains, symmetry-related by a twofold screw axis, build the crystal.

Experimental

N-Octylcarbazol-2,7-diboronic acid (1 g, 1.88 mmol) and 2-bromonitrobenzene (0.75 g, 3.71 mmol) were dissolved in toluene (4.5 ml). A solution of K₂CO₃ (2M, 3 ml) was added and the mixture was stirred for 30 min. Palladium acetate (34 mg, 0.15 mmol) and triphenylphosphine (159 mg, 0.606 mmol) were added to the stirred solution. After refluxing for 48 h, the mixture was cooled, diluted with water (15 ml) and extracted with dichloromethane (3 × 25 ml). The pooled extracts were washed with water, brine, and dried (MgSO₄). The residue was recrystallized from methanol to give the analytically pure compound. Greenish needles-like crystals suitable for X-rax analysis were grown by slow evaporation of a chloroform / methanol (1:1 v/v) solution. M. p. = 411-412 K.