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ISSN: 2056-9890

(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

(Received 27 November 2012; accepted 12 December 2012; online 19 December 2012)

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[Gomes, C. S. B., Suresh, D., Gomes, P. T., Veiros, L. F., Duarte, M. T., Nunes, T. G. & Oliveira, M. C. (2010). Dalton Trans. 39, 736-748.]); Crestani et al. (2011[Crestani, M. G., Manbeck, G. F., Brennessel, W. W., McCormick, T. M. & Eisenberg, R. (2011). Inorg. Chem. 50, 7172-7188.]); Matsui et al. (2004[Matsui, S., Yoshida, Y., Takagi, Y., Spaniol, T. P. & Okuda, J. (2004). J. Organomet. Chem. 689, 1155-1164.]); Wang et al. (2007[Wang, Y., Fu, H., Peng, A., Zhao, Y., Ma, J. & Yao, J. (2007). Chem. Commun. pp. 1623-1625.]); Franceschi et al. (2001[Franceschi, F., Guillemont, G., Solari, E., Floriani, C., Re, N., Birkedal, H. & Pattison, P. (2001). Chem. Eur. J. 7, 1468-1478.]); Tahir et al. (2010[Tahir, M. N., Tariq, M. I., Ahmad, S., Sarfraz, M. & Tariq, R. H. (2010). Acta Cryst. E66, o2295.]); Munro et al. (2006[Munro, O. Q., Joubert, S. D. & Grimmer, C. D. (2006). Chem. Eur. J. 12, 7987-7999.]). For standard bond lengths, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]). For graph-set description, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573. ]).

[Scheme 1]

Experimental

Crystal data
  • C14H16N2

  • Mr = 212.29

  • Monoclinic, P 21 /c

  • a = 13.6739 (10) Å

  • b = 7.3086 (6) Å

  • c = 13.3880 (11) Å

  • β = 111.184 (4)°

  • V = 1247.54 (17) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.07 mm−1

  • T = 183 K

  • 0.6 × 0.4 × 0.01 mm

Data collection
  • Nonius KappaCCD diffractometer

  • 4714 measured reflections

  • 2849 independent reflections

  • 1346 reflections with I > 2σ(I)

  • Rint = 0.049

Refinement
  • R[F2 > 2σ(F2)] = 0.052

  • wR(F2) = 0.127

  • S = 0.87

  • 2849 reflections

  • 152 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.16 e Å−3

  • Δρmin = −0.26 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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.

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT, Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO; 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: ORTEP-3 (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

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.

Related literature top

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 top

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%).

Refinement top

Carbon bound hydrogen atoms have been included into the refinement 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.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: 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).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound with thermal ellipsoids at the 50% probability level.
[Figure 2] Fig. 2. Centrosymmetric dimer of two molecules of the title compound connected by mutual N–H···N hydrogen bonds (symm code = 1 - x, -y, 1 - z).
(E)-2,4,6-Trimethyl-N-[(1H-pyrrol-2-yl)methylidene]aniline top
Crystal data top
C14H16N2F(000) = 456
Mr = 212.29Dx = 1.130 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 4714 reflections
a = 13.6739 (10) Åθ = 3.1–27.5°
b = 7.3086 (6) ŵ = 0.07 mm1
c = 13.3880 (11) ÅT = 183 K
β = 111.184 (4)°Plate, light yellow
V = 1247.54 (17) Å30.6 × 0.4 × 0.01 mm
Z = 4
Data collection top
Nonius KappaCCD
diffractometer
1346 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.049
Graphite monochromatorθmax = 27.5°, θmin = 3.1°
phi–scan, ω–scanh = 1717
4714 measured reflectionsk = 89
2849 independent reflectionsl = 1717
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)] = 0.052Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.127H 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 parametersΔρmax = 0.16 e Å3
0 restraintsΔρmin = 0.26 e Å3
Crystal data top
C14H16N2V = 1247.54 (17) Å3
Mr = 212.29Z = 4
Monoclinic, P21/cMo Kα radiation
a = 13.6739 (10) ŵ = 0.07 mm1
b = 7.3086 (6) ÅT = 183 K
c = 13.3880 (11) Å0.6 × 0.4 × 0.01 mm
β = 111.184 (4)°
Data collection top
Nonius KappaCCD
diffractometer
1346 reflections with I > 2σ(I)
4714 measured reflectionsRint = 0.049
2849 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0520 restraints
wR(F2) = 0.127H atoms treated by a mixture of independent and constrained refinement
S = 0.87Δρmax = 0.16 e Å3
2849 reflectionsΔρmin = 0.26 e Å3
152 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
N10.40090 (11)0.0272 (2)0.34857 (13)0.0391 (4)
H1A0.4178 (15)0.013 (3)0.4198 (17)0.054 (6)*
C10.30475 (14)0.0020 (2)0.27045 (15)0.0410 (5)
H10.24800.06380.27830.049*
C20.30352 (14)0.0875 (3)0.17859 (15)0.0419 (5)
H20.24650.09170.11190.050*
C30.40204 (13)0.1670 (2)0.20194 (15)0.0394 (5)
H30.42410.23530.15350.047*
C40.46186 (13)0.1297 (2)0.30736 (14)0.0362 (4)
C50.56546 (13)0.1952 (2)0.36830 (15)0.0383 (5)
H50.60140.26140.33090.046*
N20.61285 (11)0.1715 (2)0.46863 (12)0.0392 (4)
C60.71568 (13)0.2505 (3)0.51684 (14)0.0379 (5)
C70.80272 (14)0.1717 (3)0.50284 (16)0.0499 (5)
C80.90023 (15)0.2513 (3)0.55354 (17)0.0573 (6)
H80.95940.19830.54350.069*
C90.91517 (14)0.4035 (3)0.61769 (16)0.0505 (5)
C100.82766 (14)0.4780 (3)0.63231 (15)0.0460 (5)
H100.83610.58240.67700.055*
C110.72809 (13)0.4035 (3)0.58312 (14)0.0395 (5)
C120.79212 (18)0.0021 (4)0.4355 (2)0.0873 (9)
H12A0.86200.04590.44560.131*
H12B0.75550.03280.35980.131*
H12C0.75200.09050.45720.131*
C131.02310 (17)0.4870 (4)0.6716 (2)0.0771 (8)
H13A1.06010.48880.62110.116*
H13B1.06300.41380.73440.116*
H13C1.01590.61230.69410.116*
C140.63527 (15)0.4899 (3)0.60012 (18)0.0559 (6)
H14A0.59100.55090.53400.084*
H14B0.66000.58000.65810.084*
H14C0.59450.39510.61930.084*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0332 (8)0.0432 (9)0.0382 (10)0.0029 (7)0.0095 (8)0.0026 (8)
C10.0302 (10)0.0436 (11)0.0455 (12)0.0006 (8)0.0092 (9)0.0005 (9)
C20.0357 (10)0.0418 (11)0.0418 (12)0.0019 (9)0.0060 (9)0.0000 (9)
C30.0393 (10)0.0381 (10)0.0418 (11)0.0023 (9)0.0159 (9)0.0023 (9)
C40.0340 (10)0.0352 (10)0.0405 (11)0.0001 (8)0.0147 (9)0.0028 (8)
C50.0357 (10)0.0370 (11)0.0443 (12)0.0014 (8)0.0170 (9)0.0024 (8)
N20.0332 (8)0.0446 (9)0.0385 (10)0.0026 (7)0.0113 (7)0.0005 (7)
C60.0332 (10)0.0403 (11)0.0382 (11)0.0028 (8)0.0103 (9)0.0026 (9)
C70.0408 (11)0.0517 (13)0.0562 (13)0.0030 (10)0.0164 (10)0.0150 (10)
C80.0330 (11)0.0726 (15)0.0652 (15)0.0010 (10)0.0165 (10)0.0113 (12)
C90.0353 (11)0.0625 (14)0.0476 (12)0.0104 (10)0.0076 (10)0.0065 (11)
C100.0437 (12)0.0471 (12)0.0424 (12)0.0065 (9)0.0098 (9)0.0059 (9)
C110.0384 (10)0.0433 (11)0.0362 (11)0.0006 (9)0.0126 (9)0.0008 (9)
C120.0499 (14)0.0880 (19)0.117 (2)0.0022 (13)0.0213 (15)0.0536 (17)
C130.0420 (12)0.0964 (19)0.0839 (18)0.0194 (13)0.0121 (12)0.0216 (15)
C140.0458 (12)0.0617 (13)0.0588 (14)0.0035 (10)0.0172 (11)0.0143 (11)
Geometric parameters (Å, º) top
N1—C11.365 (2)C8—C91.375 (3)
N1—C41.376 (2)C8—H80.9500
N1—H1A0.94 (2)C9—C101.391 (3)
C1—C21.374 (3)C9—C131.517 (3)
C1—H10.9500C10—C111.392 (2)
C2—C31.395 (2)C10—H100.9500
C2—H20.9500C11—C141.507 (2)
C3—C41.379 (2)C12—H12A0.9800
C3—H30.9500C12—H12B0.9800
C4—C51.438 (2)C12—H12C0.9800
C5—N21.275 (2)C13—H13A0.9800
C5—H50.9500C13—H13B0.9800
N2—C61.439 (2)C13—H13C0.9800
C6—C71.395 (3)C14—H14A0.9800
C6—C111.399 (3)C14—H14B0.9800
C7—C81.387 (3)C14—H14C0.9800
C7—C121.509 (3)
C1—N1—C4108.76 (16)C8—C9—C10117.61 (17)
C1—N1—H1A123.3 (12)C8—C9—C13121.47 (19)
C4—N1—H1A127.7 (12)C10—C9—C13120.9 (2)
N1—C1—C2108.75 (16)C9—C10—C11121.61 (18)
N1—C1—H1125.6C9—C10—H10119.2
C2—C1—H1125.6C11—C10—H10119.2
C1—C2—C3106.88 (16)C10—C11—C6119.13 (16)
C1—C2—H2126.6C10—C11—C14119.86 (17)
C3—C2—H2126.6C6—C11—C14121.00 (16)
C4—C3—C2108.33 (16)C7—C12—H12A109.5
C4—C3—H3125.8C7—C12—H12B109.5
C2—C3—H3125.8H12A—C12—H12B109.5
N1—C4—C3107.28 (15)C7—C12—H12C109.5
N1—C4—C5124.72 (16)H12A—C12—H12C109.5
C3—C4—C5127.83 (17)H12B—C12—H12C109.5
N2—C5—C4125.03 (17)C9—C13—H13A109.5
N2—C5—H5117.5C9—C13—H13B109.5
C4—C5—H5117.5H13A—C13—H13B109.5
C5—N2—C6117.39 (15)C9—C13—H13C109.5
C7—C6—C11120.09 (16)H13A—C13—H13C109.5
C7—C6—N2121.12 (17)H13B—C13—H13C109.5
C11—C6—N2118.70 (15)C11—C14—H14A109.5
C8—C7—C6118.51 (18)C11—C14—H14B109.5
C8—C7—C12120.33 (18)H14A—C14—H14B109.5
C6—C7—C12121.15 (18)C11—C14—H14C109.5
C9—C8—C7123.01 (18)H14A—C14—H14C109.5
C9—C8—H8118.5H14B—C14—H14C109.5
C7—C8—H8118.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···N2i0.94 (2)2.05 (2)2.909 (2)150.7 (17)
Symmetry code: (i) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC14H16N2
Mr212.29
Crystal system, space groupMonoclinic, P21/c
Temperature (K)183
a, b, c (Å)13.6739 (10), 7.3086 (6), 13.3880 (11)
β (°) 111.184 (4)
V3)1247.54 (17)
Z4
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.6 × 0.4 × 0.01
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4714, 2849, 1346
Rint0.049
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.052, 0.127, 0.87
No. of reflections2849
No. of parameters152
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)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).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···N2i0.94 (2)2.05 (2)2.909 (2)150.7 (17)
Symmetry code: (i) x+1, y, z+1.
 

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.  CrossRef Web of Science
First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.   CrossRef CAS Web of Science
First citationCrestani, M. G., Manbeck, G. F., Brennessel, W. W., McCormick, T. M. & Eisenberg, R. (2011). Inorg. Chem. 50, 7172–7188.  Web of Science CSD CrossRef CAS PubMed
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals
First citationFranceschi, F., Guillemont, G., Solari, E., Floriani, C., Re, N., Birkedal, H. & Pattison, P. (2001). Chem. Eur. J. 7, 1468–1478.  Web of Science CSD CrossRef PubMed CAS
First citationGomes, C. S. B., Suresh, D., Gomes, P. T., Veiros, L. F., Duarte, M. T., Nunes, T. G. & Oliveira, M. C. (2010). Dalton Trans. 39, 736–748.  Web of Science CSD CrossRef CAS PubMed
First citationMatsui, S., Yoshida, Y., Takagi, Y., Spaniol, T. P. & Okuda, J. (2004). J. Organomet. Chem. 689, 1155–1164.  Web of Science CSD CrossRef CAS
First citationMunro, O. Q., Joubert, S. D. & Grimmer, C. D. (2006). Chem. Eur. J. 12, 7987–7999.  Web of Science CSD CrossRef PubMed CAS
First citationNonius (1998). COLLECT, Nonius BV, Delft, The Netherlands.
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter & R. M. Sweet, pp. 307–326. New York: Academic Press.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationTahir, M. N., Tariq, M. I., Ahmad, S., Sarfraz, M. & Tariq, R. H. (2010). Acta Cryst. E66, o2295.  Web of Science CSD CrossRef IUCr Journals
First citationWang, Y., Fu, H., Peng, A., Zhao, Y., Ma, J. & Yao, J. (2007). Chem. Commun. pp. 1623–1625.  Web of Science CSD CrossRef
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals

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