organic compounds
(E)-2,4,6-Trimethyl-N-[(1H-pyrrol-2-yl)methylidene]aniline
aUniversity Koblenz-Landau, Institute for Integrated Natural Sciences, Universitätsstrasse 1, 56070 Koblenz, Germany
*Correspondence e-mail: Imhof@uni-koblenz.de
The title compound, C14H16N2, is a pyrrole-2-carbaldimine ligand that shows an E conformation at the imine double bond. The dihedral angle between the rings is 78.3 (1)°. In the crystal, pairs of molecules form centrosymmetric dimers [graph-set descriptor is presumably R22(10)] via N—H⋯N hydrogen bonds between the pyrrole N—H group and the imine N atom of a neighbouring molecule.
Related literature
For structure analyses of other pyrrole-2-carbaldimines in which the substituents at the imine N atoms do not include functional groups that are capable of forming additional hydrogen bonds, see: Gomes et al. (2010); Crestani et al. (2011); Matsui et al. (2004); Wang et al. (2007); Franceschi et al. (2001); Tahir et al. (2010); Munro et al. (2006). For standard bond lengths, see: Allen et al. (1987). For graph-set description, see: Bernstein et al. (1995).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: COLLECT (Nonius, 1998); cell DENZO (Otwinowski & Minor, 1997); data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
https://doi.org/10.1107/S160053681205057X/bt6872sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681205057X/bt6872Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S160053681205057X/bt6872Isup3.cml
Pyrrol-2-carbaldehyde (400 mg, 5 mmol) and 2,4,6-trimethylaniline (680 mg, 7 mmol) were dissolved in 20 ml anhydrous ethanol in the presence of 10 mg p-toluenesulfonic acid and the reaction mixture stirred at room temperature. The progress of the reaction was monitored by TLC. After the aldehyde was consumed completely the solution was cooled down to 4°C which led to the formation of crystalline material after 2 days (yield: 890 mg, 84%).
Carbon bound hydrogen atoms have been included into the
in calculated positions with fixed thermal parameter of Uiso(H) = 1.2 Ueq(C) for aromatic C—H groups and the imine C—H function and a thermal parameter of Uiso(H) = 1.5 Ueq(C) for methyl groups. The nitrogen bound hydrogen atom H1A has been detected from difference Fourier maps and was freely refined.In the course of a project related to the supramolecular structures of square planar nickel and palladium complexes of pyrrole-2-carbaldehyde based Schiff base ligands in comparison with the structures of the free ligands the molecular structure of the title compound was determined. The free ligands form centrosymmetric dimers via N—H···N hydrogen bonds between the pyrrole NH function and the imine nitrogen atom of a neighboring molecule (Crestani et al., 2011; Gomes et al., 2010; Matsui et al., 2004; Wang et al., 2007; Franceschi et al., 2001; Tahir et al., 2010; Munro et al., 2006).
The molecular structure of the title compound is depicted in Figure 1. The C—N imine double bond shows an E-configuration. All bond lengths correspond to expected values (Allen et al., 1987). In Figure 2 the centrosymmetric dimer that is produced by two N—H···N hydrogen bonds between the pyrrole NH functions and the imine nitrogen atoms of a neighboring molecule is presented. Corresponding hydrogen bond parameters are summarized in Table 1.
For structure analyses of other pyrrole-2-carbaldimines in which the substituents at the imine N atoms do not include functional groups that are capable of forming additional hydrogen bonds, see: Gomes et al. (2010); Crestani et al. (2011); Matsui et al. (2004); Wang et al. (2007); Franceschi et al. (2001); Tahir et al. (2010); Munro et al. (2006). For standard bond lengths, see: Allen et al. (1987). For graph-set description, see: Bernstein et al. (1995).
Data collection: COLLECT (Nonius, 1998); cell
DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).C14H16N2 | F(000) = 456 |
Mr = 212.29 | Dx = 1.130 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 4714 reflections |
a = 13.6739 (10) Å | θ = 3.1–27.5° |
b = 7.3086 (6) Å | µ = 0.07 mm−1 |
c = 13.3880 (11) Å | T = 183 K |
β = 111.184 (4)° | Plate, light yellow |
V = 1247.54 (17) Å3 | 0.6 × 0.4 × 0.01 mm |
Z = 4 |
Nonius KappaCCD diffractometer | 1346 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.049 |
Graphite monochromator | θmax = 27.5°, θmin = 3.1° |
phi–scan, ω–scan | h = −17→17 |
4714 measured reflections | k = −8→9 |
2849 independent reflections | l = −17→17 |
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)] = 0.052 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.127 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | w = 1/[σ2(Fo2) + (0.0585P)2] where P = (Fo2 + 2Fc2)/3 |
2849 reflections | (Δ/σ)max = 0.032 |
152 parameters | Δρmax = 0.16 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
C14H16N2 | V = 1247.54 (17) Å3 |
Mr = 212.29 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.6739 (10) Å | µ = 0.07 mm−1 |
b = 7.3086 (6) Å | T = 183 K |
c = 13.3880 (11) Å | 0.6 × 0.4 × 0.01 mm |
β = 111.184 (4)° |
Nonius KappaCCD diffractometer | 1346 reflections with I > 2σ(I) |
4714 measured reflections | Rint = 0.049 |
2849 independent reflections |
R[F2 > 2σ(F2)] = 0.052 | 0 restraints |
wR(F2) = 0.127 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | Δρmax = 0.16 e Å−3 |
2849 reflections | Δρmin = −0.26 e Å−3 |
152 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.40090 (11) | 0.0272 (2) | 0.34857 (13) | 0.0391 (4) | |
H1A | 0.4178 (15) | −0.013 (3) | 0.4198 (17) | 0.054 (6)* | |
C1 | 0.30475 (14) | 0.0020 (2) | 0.27045 (15) | 0.0410 (5) | |
H1 | 0.2480 | −0.0638 | 0.2783 | 0.049* | |
C2 | 0.30352 (14) | 0.0875 (3) | 0.17859 (15) | 0.0419 (5) | |
H2 | 0.2465 | 0.0917 | 0.1119 | 0.050* | |
C3 | 0.40204 (13) | 0.1670 (2) | 0.20194 (15) | 0.0394 (5) | |
H3 | 0.4241 | 0.2353 | 0.1535 | 0.047* | |
C4 | 0.46186 (13) | 0.1297 (2) | 0.30736 (14) | 0.0362 (4) | |
C5 | 0.56546 (13) | 0.1952 (2) | 0.36830 (15) | 0.0383 (5) | |
H5 | 0.6014 | 0.2614 | 0.3309 | 0.046* | |
N2 | 0.61285 (11) | 0.1715 (2) | 0.46863 (12) | 0.0392 (4) | |
C6 | 0.71568 (13) | 0.2505 (3) | 0.51684 (14) | 0.0379 (5) | |
C7 | 0.80272 (14) | 0.1717 (3) | 0.50284 (16) | 0.0499 (5) | |
C8 | 0.90023 (15) | 0.2513 (3) | 0.55354 (17) | 0.0573 (6) | |
H8 | 0.9594 | 0.1983 | 0.5435 | 0.069* | |
C9 | 0.91517 (14) | 0.4035 (3) | 0.61769 (16) | 0.0505 (5) | |
C10 | 0.82766 (14) | 0.4780 (3) | 0.63231 (15) | 0.0460 (5) | |
H10 | 0.8361 | 0.5824 | 0.6770 | 0.055* | |
C11 | 0.72809 (13) | 0.4035 (3) | 0.58312 (14) | 0.0395 (5) | |
C12 | 0.79212 (18) | 0.0021 (4) | 0.4355 (2) | 0.0873 (9) | |
H12A | 0.8620 | −0.0459 | 0.4456 | 0.131* | |
H12B | 0.7555 | 0.0328 | 0.3598 | 0.131* | |
H12C | 0.7520 | −0.0905 | 0.4572 | 0.131* | |
C13 | 1.02310 (17) | 0.4870 (4) | 0.6716 (2) | 0.0771 (8) | |
H13A | 1.0601 | 0.4888 | 0.6211 | 0.116* | |
H13B | 1.0630 | 0.4138 | 0.7344 | 0.116* | |
H13C | 1.0159 | 0.6123 | 0.6941 | 0.116* | |
C14 | 0.63527 (15) | 0.4899 (3) | 0.60012 (18) | 0.0559 (6) | |
H14A | 0.5910 | 0.5509 | 0.5340 | 0.084* | |
H14B | 0.6600 | 0.5800 | 0.6581 | 0.084* | |
H14C | 0.5945 | 0.3951 | 0.6193 | 0.084* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0332 (8) | 0.0432 (9) | 0.0382 (10) | −0.0029 (7) | 0.0095 (8) | 0.0026 (8) |
C1 | 0.0302 (10) | 0.0436 (11) | 0.0455 (12) | 0.0006 (8) | 0.0092 (9) | 0.0005 (9) |
C2 | 0.0357 (10) | 0.0418 (11) | 0.0418 (12) | 0.0019 (9) | 0.0060 (9) | 0.0000 (9) |
C3 | 0.0393 (10) | 0.0381 (10) | 0.0418 (11) | 0.0023 (9) | 0.0159 (9) | 0.0023 (9) |
C4 | 0.0340 (10) | 0.0352 (10) | 0.0405 (11) | 0.0001 (8) | 0.0147 (9) | −0.0028 (8) |
C5 | 0.0357 (10) | 0.0370 (11) | 0.0443 (12) | −0.0014 (8) | 0.0170 (9) | −0.0024 (8) |
N2 | 0.0332 (8) | 0.0446 (9) | 0.0385 (10) | −0.0026 (7) | 0.0113 (7) | −0.0005 (7) |
C6 | 0.0332 (10) | 0.0403 (11) | 0.0382 (11) | −0.0028 (8) | 0.0103 (9) | 0.0026 (9) |
C7 | 0.0408 (11) | 0.0517 (13) | 0.0562 (13) | −0.0030 (10) | 0.0164 (10) | −0.0150 (10) |
C8 | 0.0330 (11) | 0.0726 (15) | 0.0652 (15) | 0.0010 (10) | 0.0165 (10) | −0.0113 (12) |
C9 | 0.0353 (11) | 0.0625 (14) | 0.0476 (12) | −0.0104 (10) | 0.0076 (10) | −0.0065 (11) |
C10 | 0.0437 (12) | 0.0471 (12) | 0.0424 (12) | −0.0065 (9) | 0.0098 (9) | −0.0059 (9) |
C11 | 0.0384 (10) | 0.0433 (11) | 0.0362 (11) | 0.0006 (9) | 0.0126 (9) | 0.0008 (9) |
C12 | 0.0499 (14) | 0.0880 (19) | 0.117 (2) | 0.0022 (13) | 0.0213 (15) | −0.0536 (17) |
C13 | 0.0420 (12) | 0.0964 (19) | 0.0839 (18) | −0.0194 (13) | 0.0121 (12) | −0.0216 (15) |
C14 | 0.0458 (12) | 0.0617 (13) | 0.0588 (14) | 0.0035 (10) | 0.0172 (11) | −0.0143 (11) |
N1—C1 | 1.365 (2) | C8—C9 | 1.375 (3) |
N1—C4 | 1.376 (2) | C8—H8 | 0.9500 |
N1—H1A | 0.94 (2) | C9—C10 | 1.391 (3) |
C1—C2 | 1.374 (3) | C9—C13 | 1.517 (3) |
C1—H1 | 0.9500 | C10—C11 | 1.392 (2) |
C2—C3 | 1.395 (2) | C10—H10 | 0.9500 |
C2—H2 | 0.9500 | C11—C14 | 1.507 (2) |
C3—C4 | 1.379 (2) | C12—H12A | 0.9800 |
C3—H3 | 0.9500 | C12—H12B | 0.9800 |
C4—C5 | 1.438 (2) | C12—H12C | 0.9800 |
C5—N2 | 1.275 (2) | C13—H13A | 0.9800 |
C5—H5 | 0.9500 | C13—H13B | 0.9800 |
N2—C6 | 1.439 (2) | C13—H13C | 0.9800 |
C6—C7 | 1.395 (3) | C14—H14A | 0.9800 |
C6—C11 | 1.399 (3) | C14—H14B | 0.9800 |
C7—C8 | 1.387 (3) | C14—H14C | 0.9800 |
C7—C12 | 1.509 (3) | ||
C1—N1—C4 | 108.76 (16) | C8—C9—C10 | 117.61 (17) |
C1—N1—H1A | 123.3 (12) | C8—C9—C13 | 121.47 (19) |
C4—N1—H1A | 127.7 (12) | C10—C9—C13 | 120.9 (2) |
N1—C1—C2 | 108.75 (16) | C9—C10—C11 | 121.61 (18) |
N1—C1—H1 | 125.6 | C9—C10—H10 | 119.2 |
C2—C1—H1 | 125.6 | C11—C10—H10 | 119.2 |
C1—C2—C3 | 106.88 (16) | C10—C11—C6 | 119.13 (16) |
C1—C2—H2 | 126.6 | C10—C11—C14 | 119.86 (17) |
C3—C2—H2 | 126.6 | C6—C11—C14 | 121.00 (16) |
C4—C3—C2 | 108.33 (16) | C7—C12—H12A | 109.5 |
C4—C3—H3 | 125.8 | C7—C12—H12B | 109.5 |
C2—C3—H3 | 125.8 | H12A—C12—H12B | 109.5 |
N1—C4—C3 | 107.28 (15) | C7—C12—H12C | 109.5 |
N1—C4—C5 | 124.72 (16) | H12A—C12—H12C | 109.5 |
C3—C4—C5 | 127.83 (17) | H12B—C12—H12C | 109.5 |
N2—C5—C4 | 125.03 (17) | C9—C13—H13A | 109.5 |
N2—C5—H5 | 117.5 | C9—C13—H13B | 109.5 |
C4—C5—H5 | 117.5 | H13A—C13—H13B | 109.5 |
C5—N2—C6 | 117.39 (15) | C9—C13—H13C | 109.5 |
C7—C6—C11 | 120.09 (16) | H13A—C13—H13C | 109.5 |
C7—C6—N2 | 121.12 (17) | H13B—C13—H13C | 109.5 |
C11—C6—N2 | 118.70 (15) | C11—C14—H14A | 109.5 |
C8—C7—C6 | 118.51 (18) | C11—C14—H14B | 109.5 |
C8—C7—C12 | 120.33 (18) | H14A—C14—H14B | 109.5 |
C6—C7—C12 | 121.15 (18) | C11—C14—H14C | 109.5 |
C9—C8—C7 | 123.01 (18) | H14A—C14—H14C | 109.5 |
C9—C8—H8 | 118.5 | H14B—C14—H14C | 109.5 |
C7—C8—H8 | 118.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···N2i | 0.94 (2) | 2.05 (2) | 2.909 (2) | 150.7 (17) |
Symmetry code: (i) −x+1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C14H16N2 |
Mr | 212.29 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 183 |
a, b, c (Å) | 13.6739 (10), 7.3086 (6), 13.3880 (11) |
β (°) | 111.184 (4) |
V (Å3) | 1247.54 (17) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.6 × 0.4 × 0.01 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4714, 2849, 1346 |
Rint | 0.049 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.052, 0.127, 0.87 |
No. of reflections | 2849 |
No. of parameters | 152 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.16, −0.26 |
Computer programs: COLLECT (Nonius, 1998), DENZO (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 2012), publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···N2i | 0.94 (2) | 2.05 (2) | 2.909 (2) | 150.7 (17) |
Symmetry code: (i) −x+1, −y, −z+1. |
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
In the course of a project related to the supramolecular structures of square planar nickel and palladium complexes of pyrrole-2-carbaldehyde based Schiff base ligands in comparison with the structures of the free ligands the molecular structure of the title compound was determined. The free ligands form centrosymmetric dimers via N—H···N hydrogen bonds between the pyrrole NH function and the imine nitrogen atom of a neighboring molecule (Crestani et al., 2011; Gomes et al., 2010; Matsui et al., 2004; Wang et al., 2007; Franceschi et al., 2001; Tahir et al., 2010; Munro et al., 2006).
The molecular structure of the title compound is depicted in Figure 1. The C—N imine double bond shows an E-configuration. All bond lengths correspond to expected values (Allen et al., 1987). In Figure 2 the centrosymmetric dimer that is produced by two N—H···N hydrogen bonds between the pyrrole NH functions and the imine nitrogen atoms of a neighboring molecule is presented. Corresponding hydrogen bond parameters are summarized in Table 1.