research communications
Z)-6-[(5-chloro-2-methoxyanilino)methylidene]-2-hydroxycyclohexa-2,4-dien-1-one
and Hirshfeld surface analysis of a Schiff base: (aGaziantep University, Technical Sciences, 27310, Gaziantep, Turkey, bOndokuz Mayıs University, Faculty of Arts and Sciences, Department of Chemistry, 55139, Kurupelit, Samsun, Turkey, cScience Research and Applied Center, Van Yuzuncu Yil University, 65080, Van, Turkey, dOndokuz Mayıs University, Faculty of Arts and Sciences, Department of Physics, 55139, Kurupelit, Samsun, Turkey, and eDepartment of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska 64/13, 01601 Kyiv, Ukraine
*Correspondence e-mail: sibeld@gantep.edu.tr, necmid@omu.edu.tr, ifritsky@univ.kiev.ua
The title compound, C14H12ClNO3, is a Schiff base that exists in the keto–enamine tautomeric form and adopts a Z configuration. In the crystal, the dihedral angle between the planes of the benzene rings is 5.34 (15)°. The roughly planar geometry of the molecule is stabilized by a strong intramolecular N—H⋯O hydrogen bond. In the crystal, pairs of centrosymmetrically related molecules are linked by O—H⋯O hydrogen bonds, forming R22(10) rings. Besides this, the molecules form stacks along the [001] direction with C—H⋯π and C—H⋯Cl contacts between the stacks. The intermolecular interactions in the crystal were analysed using Hirshfeld surfaces. The most significant contribution to the crystal packing is from H⋯H contacts (30.8%).
Keywords: crystal structure; Schiff bases; Hirshfeld surface; hydrogen bonds; stacking interactions.
CCDC reference: 1886956
1. Chemical context
) and they are also of interest in various fields because of their diverse biological activity (Lozier et al., 1975; Costamagna et al., 1992). Some derived from salicylaldehyde have attracted the interest of chemists and physicists because they show thermochromism and in the solid state (Cohen et al., 1964; Hadjoudis et al., 1987). The origin of their photo- and thermochromism is related to the reversible intramolecular proton transfer associated with a change in the electronic structure (Hadjoudis et al., 1987). The o-hydroxy obtained by the condensation of o-hydroxyaldehydes with aniline have been extensively examined in this context. Such compounds can exist in two tautomeric forms, viz. keto–enamine (N—H⋯O) and phenol–imine (N⋯H—O) (Stewart & Lingafelter, 1959; Petek et al., 2010). We report herein the synthesis and the crystal and molecular structures of the title compound, as well as an analysis of its Hirshfeld surfaces.
are widely used as ligands in coordination chemistry (Calligaris & Randaccio, 19872. Structural commentary
As shown in Fig. 1., the of the title compound contains only one molecule, which adopts the keto–enamine tautomeric form: the H atom is located at N1, and the lengths of the N1—C7 and C8—C9 bonds indicate their single-bond character, whereas the O2—C9 and C7—C8 bonds are double (Table 1). Overall, the bond lengths in the title structure compare well with those of other keto–enamine tautomers known from the literature (see the Database survey section). The whole molecule is almost planar, with a dihedral angle of 5.34 (15)° between the benzene ring planes. The methoxy C14 atom deviates from the plane of the C1–C6 benzene ring by 0.038 (4) Å. The torsion angles C1—C6—N1—C7 and N1—C7—C8—C9 are 5.8 (5) and −0.6 (5)°, respectively. The planar molecular conformation is stabilized by the intramolecular N1—H2⋯O2 hydrogen bond (Table 2).
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3. Supramolecular features
In the crystal, the molecules are connected via O—H⋯O hydrogen bonds into centrosymmetric pairs with an R22(10) graph-set motif (Table 2, Fig. 2). Molecules related by a [001] translation form stacks with an interplanar distance of 3.420 (3) Å and a shortest intercentroid separation of 3.6797 (17) Å. The molecular packing is further stabilized by C—H⋯O, C—H⋯Cl and C—H⋯π interactions between the molecules of the neighbouring stacks (Fig. 3). Details of all these contacts are given in Table 2.
4. Database survey
A search of the Cambridge Structural database (CSD, version 5.40, update November 2018; Groom et al., 2016) for the 3-[(E)-(phenylimino)methyl]-benzene-1,2-diol fragment revealed eight hits where this fragment adopts the keto–enamine tautomeric form and 21 hits where it exists as the phenol–imine tautomer. Distinctive bond lengths (N1—C7, C7=C8, C8—C9, C9=O2) in the title structure are the same within standard uncertainties as the corresponding bond lengths in the structures of 2-hydroxy-6-[(2-methoxyphenyl)aminomethylene]cyclohexa-2,4-dienone (FOCCOQ; Şahin et al., 2005) and 6-[(4-chlorophenylamino)methylene]-2,3-dihydroxycyclohexa-2,4-dien-1-one (CIRTED; Karabıyık et al., 2008). In the structures of typical phenol–imine tautomers, viz., 3-[(3-bromophenyl)iminomethyl]benzene-1,2-diol (CUCZUW; Keleşoğlu et al., 2009b), 3-[(2-bromophenyl)iminomethyl]benzene-1,2-diol (XEYSOK; Temel et al., 2007) and 3-[(4-butylphenyl)iminomethyl]benzene-1,2-diol (XOZJUS; Keleşoğlu et al., 2009a), the C9—O2 and C7—C8 bond lengths are distinctly longer, being in the ranges 1.324–1.355 Å and 1.427–1.447 Å, respectively. It is likely that the intermolecular O—H⋯O hydrogen bond, where the keto O atom acts as an hydrogen-bond acceptor, is an important prerequisite for the tautomeric shift toward the keto–enamine form. In fact, in all eight structures of the keto–enamine tautomers, hydrogen bonds of this type are observed. However, in 16 of 21 structures of phenol–imine tautomers, such hydrogen bonds are also present. This means that there is another unknown reason for the formation of keto–enamine tautomers.
5. Hirshfeld surface analysis
The Hirshfeld surface analysis, together with the two-dimensional fingerprint plots, is a powerful tool for the visualization and interpretation of intermolecular contacts in molecular crystals, since it provides a concise description of all intermolecular interactions present in a ; McKinnon et al., 2007). All surfaces and 2D fingerprint plots were generated using CrystalExplorer3.1 (Wolff et al., 2012). The mappings of di, de, dnorm, shape-index and curvedness for the title structure are shown in Fig. 4. The Hirshfeld surface of a molecule in the crystal is presented in Fig. 5, with the prominent hydrogen-bonding interactions shown as intense red spots. The two-dimensional fingerprint plots provide information about the percentage contributions of the various interatomic contacts. As can be seen from these plots (Fig. 6), the most important are the H⋯H interactions, which contribute 30.8% to the total Hirshfeld surface. Other contributions are from O⋯C/C⋯O (1.2%), O⋯H/H⋯O (17.2%), C⋯C (7.2%), O⋯O/O⋯O (1.0%), Cl⋯H/H⋯Cl (17.8%) and C⋯H/H⋯C (21.8%). Analogous features were observed recently for some compounds of the same class (Kansız et al., 2018; Özek Yıldırım et al., 2018). The donor and acceptor centers of the hydrogen bonding are represented as blue (positive) and red (negative) regions on the Hirshfeld surface mapped over the electrostatic potential (Fig. 7). The electrostatic potential of the Cl01 atom is less negative as compared to those of atoms O2 and O3 of the hydroxy groups, as indicated by the lighter red color.
(Spackman & Jayatilaka, 20096. Synthesis and crystallization
The title compound was prepared by mixing solutions of 2,3-dihydroxybenzaldehyde (34.5 mg, 0.25 mmol) and 5-chloro-2-methoxyaniline (39.4 mg, 0.25 mmol), both in 15 mL of ethanol, with subsequent stirring for 5 h under reflux. Single crystals were obtained by slow evaporation of an ethanol solution (yield 65%; m.p. 442–444 K).
7. Refinement
Crystal data, data collection and structure . The C-bound H atoms were geometrically positioned with C—H distances of 0.93–0.96 Å and refined as riding, with Uiso(H) = 1.2Ueq(C) or Uiso(H) = 1.5Ueq(C) for methyl H atoms. The O- and N-bound H atoms were located in a difference map and freely refined.
details are summarized in Table 3
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Supporting information
CCDC reference: 1886956
https://doi.org/10.1107/S2056989019002123/yk2119sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019002123/yk2119Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989019002123/yk2119Isup3.cml
Data collection: X-AREA (Stoe & Cie, 2002); cell
X-AREA (Stoe & Cie, 2002); data reduction: X-RED (Stoe & Cie, 2002); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012)and PLATON (Spek, 2009).C14H12ClNO3 | F(000) = 576 |
Mr = 277.70 | Dx = 1.420 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 14.7251 (9) Å | Cell parameters from 8086 reflections |
b = 14.4444 (9) Å | θ = 1.4–27.1° |
c = 6.1698 (4) Å | µ = 0.30 mm−1 |
β = 98.241 (5)° | T = 296 K |
V = 1298.74 (14) Å3 | Irregular specimen, red |
Z = 4 | 0.23 × 0.16 × 0.09 mm |
Stoe IPDS 2 diffractometer | 2491 independent reflections |
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus | 1120 reflections with I > 2σ(I) |
Detector resolution: 6.67 pixels mm-1 | Rint = 0.115 |
rotation method scans | θmax = 26.0°, θmin = 2.0° |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | h = −18→18 |
Tmin = 0.948, Tmax = 0.979 | k = −17→17 |
13658 measured reflections | l = −7→7 |
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)] = 0.057 | Hydrogen site location: mixed |
wR(F2) = 0.100 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.90 | w = 1/[σ2(Fo2) + (0.0293P)2] where P = (Fo2 + 2Fc2)/3 |
2491 reflections | (Δ/σ)max < 0.001 |
181 parameters | Δρmax = 0.16 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Cl01 | 0.49115 (8) | 0.36774 (9) | −0.2476 (2) | 0.1172 (6) | |
O1 | 0.11503 (15) | 0.37573 (16) | −0.0556 (4) | 0.0611 (6) | |
O2 | 0.10563 (15) | 0.50349 (16) | 0.4247 (4) | 0.0601 (7) | |
O3 | 0.0461 (2) | 0.5981 (2) | 0.7618 (4) | 0.0782 (9) | |
N1 | 0.2392 (2) | 0.46609 (18) | 0.2056 (5) | 0.0497 (8) | |
C1 | 0.3568 (2) | 0.4173 (2) | −0.0160 (6) | 0.0608 (10) | |
H1A | 0.4026 | 0.4475 | 0.0774 | 0.073* | |
C2 | 0.3782 (2) | 0.3706 (2) | −0.1958 (6) | 0.0606 (10) | |
C3 | 0.3124 (2) | 0.3262 (2) | −0.3362 (6) | 0.0583 (10) | |
H3A | 0.3277 | 0.2961 | −0.4592 | 0.070* | |
C4 | 0.2231 (2) | 0.3264 (2) | −0.2937 (6) | 0.0540 (9) | |
H4 | 0.1780 | 0.2953 | −0.3869 | 0.065* | |
C5 | 0.2002 (2) | 0.3725 (2) | −0.1142 (5) | 0.0459 (8) | |
C6 | 0.2675 (2) | 0.4193 (2) | 0.0256 (5) | 0.0454 (8) | |
C7 | 0.2902 (2) | 0.5189 (2) | 0.3445 (6) | 0.0546 (9) | |
H7 | 0.3515 | 0.5266 | 0.3277 | 0.066* | |
C8 | 0.2572 (2) | 0.5648 (2) | 0.5188 (5) | 0.0495 (9) | |
C9 | 0.1632 (2) | 0.5551 (2) | 0.5481 (5) | 0.0483 (9) | |
C10 | 0.1348 (3) | 0.6045 (2) | 0.7269 (6) | 0.0577 (9) | |
C11 | 0.1941 (3) | 0.6591 (2) | 0.8593 (6) | 0.0669 (11) | |
H11 | 0.1733 | 0.6919 | 0.9723 | 0.080* | |
C12 | 0.2862 (3) | 0.6667 (2) | 0.8274 (6) | 0.0680 (11) | |
H12 | 0.3262 | 0.7037 | 0.9205 | 0.082* | |
C13 | 0.3171 (3) | 0.6206 (2) | 0.6623 (6) | 0.0619 (10) | |
H13 | 0.3784 | 0.6257 | 0.6430 | 0.074* | |
C14 | 0.0424 (2) | 0.3301 (3) | −0.1933 (6) | 0.0698 (11) | |
H00F | 0.0378 | 0.3546 | −0.3392 | 0.105* | |
H14B | −0.0144 | 0.3402 | −0.1375 | 0.105* | |
H14C | 0.0548 | 0.2649 | −0.1959 | 0.105* | |
H3 | 0.016 (3) | 0.555 (3) | 0.685 (8) | 0.104 (18)* | |
H2 | 0.175 (3) | 0.461 (3) | 0.226 (8) | 0.130 (17)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl01 | 0.0754 (8) | 0.1458 (11) | 0.1426 (12) | −0.0326 (7) | 0.0573 (8) | −0.0628 (9) |
O1 | 0.0504 (14) | 0.0746 (16) | 0.0578 (16) | −0.0021 (13) | 0.0062 (12) | −0.0180 (13) |
O2 | 0.0581 (15) | 0.0667 (16) | 0.0544 (17) | −0.0025 (13) | 0.0051 (13) | −0.0148 (12) |
O3 | 0.077 (2) | 0.087 (2) | 0.074 (2) | 0.0025 (16) | 0.0234 (17) | −0.0277 (16) |
N1 | 0.0535 (19) | 0.0501 (19) | 0.047 (2) | −0.0040 (14) | 0.0114 (17) | −0.0032 (14) |
C1 | 0.063 (3) | 0.060 (2) | 0.061 (3) | −0.0134 (17) | 0.014 (2) | −0.0135 (18) |
C2 | 0.061 (2) | 0.057 (2) | 0.068 (3) | −0.011 (2) | 0.025 (2) | −0.010 (2) |
C3 | 0.073 (3) | 0.050 (2) | 0.056 (3) | 0.001 (2) | 0.019 (2) | −0.0059 (19) |
C4 | 0.060 (3) | 0.048 (2) | 0.053 (2) | −0.0013 (17) | 0.005 (2) | −0.0097 (17) |
C5 | 0.051 (2) | 0.043 (2) | 0.044 (2) | 0.0025 (17) | 0.0085 (18) | 0.0000 (17) |
C6 | 0.055 (2) | 0.041 (2) | 0.041 (2) | −0.0018 (16) | 0.0093 (19) | −0.0023 (15) |
C7 | 0.059 (2) | 0.052 (2) | 0.053 (2) | −0.0125 (18) | 0.010 (2) | −0.0031 (19) |
C8 | 0.063 (2) | 0.042 (2) | 0.043 (2) | −0.0008 (16) | 0.0073 (19) | −0.0044 (16) |
C9 | 0.067 (2) | 0.0347 (19) | 0.042 (2) | 0.0064 (17) | 0.004 (2) | −0.0009 (16) |
C10 | 0.072 (3) | 0.050 (2) | 0.052 (2) | 0.007 (2) | 0.011 (2) | −0.0005 (19) |
C11 | 0.093 (3) | 0.056 (3) | 0.053 (3) | 0.007 (2) | 0.015 (2) | −0.0073 (19) |
C12 | 0.088 (3) | 0.058 (2) | 0.055 (3) | −0.011 (2) | 0.000 (2) | −0.015 (2) |
C13 | 0.074 (2) | 0.054 (2) | 0.057 (3) | −0.010 (2) | 0.008 (2) | −0.0087 (19) |
C14 | 0.053 (2) | 0.095 (3) | 0.060 (3) | −0.002 (2) | 0.002 (2) | −0.010 (2) |
Cl01—C2 | 1.739 (3) | C4—H4 | 0.9300 |
O1—C5 | 1.354 (3) | C5—C6 | 1.393 (4) |
O1—C14 | 1.429 (4) | C7—C8 | 1.408 (4) |
O2—C9 | 1.292 (4) | C7—H7 | 0.9300 |
O3—C10 | 1.358 (4) | C8—C9 | 1.429 (4) |
O3—H3 | 0.87 (4) | C8—C13 | 1.410 (5) |
N1—C6 | 1.413 (4) | C9—C10 | 1.426 (4) |
N1—C7 | 1.302 (4) | C10—C11 | 1.359 (5) |
N1—H2 | 0.97 (4) | C11—C12 | 1.402 (5) |
C1—C2 | 1.372 (4) | C11—H11 | 0.9300 |
C1—C6 | 1.376 (4) | C12—C13 | 1.349 (4) |
C1—H1A | 0.9300 | C12—H12 | 0.9300 |
C2—C3 | 1.363 (5) | C13—H13 | 0.9300 |
C3—C4 | 1.379 (4) | C14—H00F | 0.9600 |
C3—H3A | 0.9300 | C14—H14B | 0.9600 |
C4—C5 | 1.375 (4) | C14—H14C | 0.9600 |
C5—O1—C14 | 117.9 (3) | C8—C7—H7 | 118.3 |
C10—O3—H3 | 113 (3) | C7—C8—C13 | 119.7 (3) |
C7—N1—C6 | 126.1 (3) | C7—C8—C9 | 119.8 (3) |
C7—N1—H2 | 116 (3) | C13—C8—C9 | 120.4 (3) |
C6—N1—H2 | 118 (3) | O2—C9—C10 | 120.3 (3) |
C2—C1—C6 | 119.8 (3) | O2—C9—C8 | 123.2 (3) |
C2—C1—H1A | 120.1 | C10—C9—C8 | 116.5 (3) |
C6—C1—H1A | 120.1 | O3—C10—C11 | 119.6 (3) |
C3—C2—C1 | 121.4 (3) | O3—C10—C9 | 118.9 (4) |
C3—C2—Cl01 | 118.9 (3) | C11—C10—C9 | 121.4 (3) |
C1—C2—Cl01 | 119.7 (3) | C10—C11—C12 | 120.8 (3) |
C2—C3—C4 | 119.2 (3) | C10—C11—H11 | 119.6 |
C2—C3—H3A | 120.4 | C12—C11—H11 | 119.6 |
C4—C3—H3A | 120.4 | C13—C12—C11 | 120.3 (4) |
C5—C4—C3 | 120.4 (3) | C13—C12—H12 | 119.8 |
C5—C4—H4 | 119.8 | C11—C12—H12 | 119.8 |
C3—C4—H4 | 119.8 | C12—C13—C8 | 120.5 (3) |
O1—C5—C4 | 125.1 (3) | C12—C13—H13 | 119.7 |
O1—C5—C6 | 115.0 (3) | C8—C13—H13 | 119.7 |
C4—C5—C6 | 119.9 (3) | O1—C14—H00F | 109.5 |
C1—C6—C5 | 119.3 (3) | O1—C14—H14B | 109.5 |
C1—C6—N1 | 123.7 (3) | H00F—C14—H14B | 109.5 |
C5—C6—N1 | 117.0 (3) | O1—C14—H14C | 109.5 |
N1—C7—C8 | 123.3 (3) | H00F—C14—H14C | 109.5 |
N1—C7—H7 | 118.3 | H14B—C14—H14C | 109.5 |
C6—C1—C2—C3 | 0.3 (6) | C6—N1—C7—C8 | 179.0 (3) |
C6—C1—C2—Cl01 | −179.7 (3) | N1—C7—C8—C13 | 179.9 (3) |
C1—C2—C3—C4 | −1.5 (6) | N1—C7—C8—C9 | −0.6 (5) |
Cl01—C2—C3—C4 | 178.6 (3) | C7—C8—C9—O2 | 2.0 (5) |
C2—C3—C4—C5 | 1.3 (5) | C13—C8—C9—O2 | −178.5 (3) |
C14—O1—C5—C4 | −1.8 (5) | C7—C8—C9—C10 | −179.3 (3) |
C14—O1—C5—C6 | 179.2 (3) | C13—C8—C9—C10 | 0.1 (5) |
C3—C4—C5—O1 | −178.8 (3) | O2—C9—C10—O3 | −1.5 (5) |
C3—C4—C5—C6 | 0.1 (5) | C8—C9—C10—O3 | 179.8 (3) |
C2—C1—C6—C5 | 1.0 (5) | O2—C9—C10—C11 | 179.8 (3) |
C2—C1—C6—N1 | −179.5 (3) | C8—C9—C10—C11 | 1.2 (5) |
O1—C5—C6—C1 | 177.8 (3) | O3—C10—C11—C12 | 179.7 (3) |
C4—C5—C6—C1 | −1.2 (5) | C9—C10—C11—C12 | −1.7 (6) |
O1—C5—C6—N1 | −1.7 (4) | C10—C11—C12—C13 | 0.9 (6) |
C4—C5—C6—N1 | 179.3 (3) | C11—C12—C13—C8 | 0.4 (6) |
C7—N1—C6—C1 | 5.8 (5) | C7—C8—C13—C12 | 178.6 (3) |
C7—N1—C6—C5 | −174.7 (3) | C9—C8—C13—C12 | −0.9 (5) |
Cg1 is the centroid of the C1–C6 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C7—H7···Cl01i | 0.93 | 2.88 | 3.737 (3) | 154 |
C14—H14B···O3ii | 0.96 | 2.59 | 3.295 (4) | 131 |
O3—H3···O2ii | 0.87 (4) | 2.00 (4) | 2.780 (4) | 148 (4) |
N1—H2···O2 | 0.97 (4) | 1.82 (4) | 2.598 (3) | 136 (4) |
C3—H3A···Cg1iii | 0.93 | 2.73 | 3.463 (3) | 136 |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x, −y+1, −z+1; (iii) x, −y+1/2, z−1/2. |
Acknowledgements
The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund).
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