2,5-Dimethyl-N-[1-(1H-pyrrol-2-yl)ethyl­idene]aniline

Bi-Yun Su; Wen-Long Qin; Jia-Xiang Wang

doi:10.1107/S1600536812040858

. 2012 Oct 6;68(Pt 11):o3088. doi: 10.1107/S1600536812040858

2,5-Dimethyl-N-[1-(1H-pyrrol-2-yl)ethylidene]aniline

Bi-Yun Su ^a,^*, Wen-Long Qin ^b, Jia-Xiang Wang ^a

PMCID: PMC3515192 PMID: 23284419

Abstract

In the title compound, C₁₄H₁₆N₂, the pyrrole and benzene rings form a dihedral angle of 72.37 (8)°. In the crystal, centrosymmetrically related molecules are assembled into dimers by by pairs of N—H⋯N hydrogen bonds, generating rings of R ₂ ²(10) graph-set motif. C—H⋯π interactions also occur.

Related literature

For general background to the iminopyrrole unit, see: Britovsek et al. (2003 ▶); Dawson et al. (2000 ▶); Wu et al. (2003 ▶). For the pyrrole diimine unit, see: Matsuo et al. (2001 ▶) and for the pyrrole monoimine unit, see: He et al. (2009 ▶); Su et al. (2009a ▶,b ▶).

Experimental

Crystal data

C₁₄H₁₆N₂
M _r = 212.29
Monoclinic,
a = 12.5894 (17) Å
b = 7.3109 (10) Å
c = 14.8425 (19) Å
β = 113.118 (2)°
V = 1256.4 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 296 K
0.37 × 0.28 × 0.15 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.976, T _max = 0.990
6463 measured reflections
2441 independent reflections
1885 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.156
S = 0.96
2441 reflections
149 parameters
H-atom parameters constrained
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: APEX2 (Bruker,2008 ▶); cell refinement: SAINT (Bruker,2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(16.7KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812040858/rz5010sup1.cif

e-68-o3088-sup1.cif^{(16.7KB, cif)}

Click here for additional data file.^{(120KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812040858/rz5010Isup2.hkl

e-68-o3088-Isup2.hkl^{(120KB, hkl)}

Click here for additional data file.^{(4.8KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812040858/rz5010Isup3.cml

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

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C7–C12 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯N2ⁱ	0.86	2.34	3.1354 (18)	155
C1—H1A⋯Cg1ⁱ	0.93	2.65	3.4298 (16)	142

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by the Natural Science Basic Research Plan of Shaanxi Province (No. 2009JQ2006) and the Scientific Research Plan Project of Shaanxi Education Department (Nos. 12 J K0620 and 2010 J K784).

supplementary crystallographic information

Comment

Bis(imino)pyrrole is usually prepared from Schiff bases condensation of 2,5-diacetylpyrrole and the aromatic amine (Matsuo et al., 2001). Schiff bases containing pyrrole units have been extensively investigated because of their excellent and flexible coordination abilities (Wu et al., 2003). As the five-memberd ring substitute of pyridine six-memberd ring (Matsuo et al., 2001; He et al., 2009), pyrrole has been frequently introduced into the skeleton of the bis(imino)pyridine ligand to design new ligands and corresponding metal complexes as catalysts of olefin polymerizations (Britovsek et al., 2003; Dawson et al., 2000). As a part of our studies on mono(imino)pyrrole ligands (Su et al., 2009a,b), the crystal structure of the title compound is reported here.

The X-ray analysis of the title compound (Fig. 1) shows that the molecule is non-planar, with a dihedral angle of 72.37 (8)° formed by the pyrrole and benzene rings. The imino N—C bond length (1.288 (2) Å) indicates a C═N double bond character. In the crystal (Fig. 2), a pair of classical N–H···N hydrogen bonds (Table 1) link centrosymmetrically related molecules into a dimer, generating a ring of R₂²(10) graph-set motif. The dimer is further enforced by C—H···π hydrogen interactions.

Experimental

The reagents 2-acetyl pyrrole (0.1528 g, 1.40 mmol) and 2,5-dimethylaniline (0.3393 g, 2.80 mmol) were placed in a 50-ml flask. A few drops of acetic acid was then added in, and the mixture was subjected to radiation in a 800 W microwave oven for 3 min and 2 min on a medium–heat setting. The reaction was monitored by TLC, and the crude product was purified by silica gel column chromatography (eluant: petroleum ether/ethyl acetate, 5:1 v/v). Plate-like colourless single crystals used in X-ray diffraction studies were grown from an ethanolic solution by slow evaporation of the solvent at room temperature; yield 72.79%, 0.2982 g. M.p. 396.8–398.4 K. The purity and the composition of the compound were checked and characterized by IR, ¹H NMR, mass spectrum, as well as elemental analysis. IR (KBr): ν_C=N 1659 cm^-1. ¹H NMR (400 MHz, CDCl₃): δ 7.12 (d, 1H, benzene ring aromatic H), δ 7.09 (d, 1H, benzene ring aromatic H), 6.88 (m, 1H, benzene ring aromatic H), 6.56 (d, 1H, pyrrole ring aromatic H), 6.37 (s, 1H, pyrrole ring aromatic H), 6.18 (d, 1H, pyrrole ring aromatic H), 2.18 (s, 6H, phenyl-CH₃), 2.05 (s, 3H, –N=C(CH₃)-). MS (EI): m/z 212 (M). Anal. Calcd. for C₁₄H₁₆N₂: C, 79.21; H, 7.60; N, 13.20. Found: C, 79.72; H, 7.13; N, 12.84.