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ISSN: 2414-3146

6-[(2-Hy­dr­oxy-5-methyl­anilino)methyl­­idene]-4-nitro­cyclo­hexa-2,4-dien-1-one

aInstitut für Anorganische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
*Correspondence e-mail: uwe.boehme@chemie.tu-freiberg.de

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 15 October 2020; accepted 16 October 2020; online 23 October 2020)

The title compound, C14H12N2O4, is nearly planar with a dihedral angle between the aromatic rings of 1.41 (8)°. The phenolic O atom is deprotonated and the N atom of the azomethine unit carries the proton, thereby forming an intra­molecular N—H⋯O hydrogen bond. In the crystal, the mol­ecules form inversion dimers via pairwise O—H⋯O hydrogen bonds.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Aromatic Schiff bases with ortho-hy­droxy groups are useful as acyclic polydentate ligands for the preparation of chelate complexes with a wide variety of metal ions (Freeman & White, 1956[Freeman, D. C. & White, C. E. (1956). J. Am. Chem. Soc. 78, 2678-2682.]; Calligaris & Randaccio, 1987[Calligaris, M. & Randaccio, L. (1987). Comprehensive Coordination Chemistry, Vol. 2, edited by G. Wilkinson, R. D. Gillard, J. A. McCleverty, pp. 715-738. Oxford: Pergamon Press.]; Pettinari et al., 2001[Pettinari, C., Marchetti, F., Pettinari, R., Martini, D., Drozdov, A. & Troyanov, S. (2001). Inorg. Chim. Acta, 325, 103-114.]; Hernández-Molina & Mederos, 2004[Hernández-Molina, R. & Mederos, A. (2004). Comprehensive Coordination Chemistry II, Vol. 1, edited by J. A. McCleverty, T. J. Meyer, pp. 411-446. Amsterdam: Elsevier.]). We are working on silicon, tin, and titanium complexes with tridentate O,N,O-ligands (Böhme & Günther, 2006[Böhme, U. & Günther, B. (2006). Acta Cryst. E62, m1711-m1712.], 2007[Böhme, U. & Günther, B. (2007). Inorg. Chem. Commun. 10, 482-484.]; Böhme et al., 2006[Böhme, U., Wiesner, S. & Günther, B. (2006). Inorg. Chem. Commun. 9, 806-809.]; Paul et al., 2014[Paul, L. E. H., Foehn, I. C., Schwarzer, A., Brendler, E. & Böhme, U. (2014). Inorg. Chim. Acta, 423, 268-280.]; Warncke et al., 2012[Warncke, G., Böhme, U., Günther, B. & Kronstein, M. (2012). Polyhedron, 47, 46-52.], 2016[Warncke, G., Fels, S., Brendler, E. & Böhme, U. (2016). J. Mol. Struct. 1117, 37-48.]; Schwarzer et al., 2018[Schwarzer, S., Böhme, U., Fels, S., Günther, B. & Brendler, E. (2018). Inorg. Chim. Acta, 483, 136-147.]).

The title compound was prepared in order to extend the series of available ligands. Its preparation was performed according to methods described in the literature for the parent compound salicycl­idene-o-amino­phenol (salopH2; Freeman & White, 1956[Freeman, D. C. & White, C. E. (1956). J. Am. Chem. Soc. 78, 2678-2682.]; Pettinari et al., 2001[Pettinari, C., Marchetti, F., Pettinari, R., Martini, D., Drozdov, A. & Troyanov, S. (2001). Inorg. Chim. Acta, 325, 103-114.]) by the reaction of 2-hy­droxy-5-nitro­benzaldehyde and 2-amino-4-methyl­phenol in ethanol.

The mol­ecule is nearly planar with a dihedral angle between the aromatic rings of 1.41 (8)°. Atom H2 forms an intra­molecular hydrogen bond (Table 1[link], Fig. 1[link]) between the phenolic oxygen atom O1 and N1 of the azomethine unit: the hydrogen atom is localized at a distance of 0.93 (2) Å from N1, indicating the presence of the keto–amine form. The presence of a quinoidal structure is further supported by the shortening of the bond C3—O1 to 1.2734 (19) Å and the lengthening of the adjacent C—C bonds in the phenyl ring [C2—C3 = 1.446 (2), C3—C4 = 1.420 (2) Å] (Nazır et al., 2000[Nazır, H., Yıldız, M., Yılmaz, H., Tahir, M. & Ülkü, D. (2000). J. Mol. Struct. 524, 241-250.]; Warncke et al., 2016[Warncke, G., Fels, S., Brendler, E. & Böhme, U. (2016). J. Mol. Struct. 1117, 37-48.]). There are several structure reports of Schiff bases with an oxygen atom in the ortho-position where the intra­molecular bridging hydrogen atom is localized at the nitro­gen atom (e.g. Pradeep, 2005[Pradeep, C. P. (2005). Acta Cryst. E61, o3825-o3827.]; Dubs et al., 2000[Dubs, M., Krieg, R., Görls, H. & Schönecker, B. (2000). Steroids, 65, 305-318.]; Höpfl et al., 1998[Höpfl, H., Sánchez, M., Barba, V., Farfán, N., Rojas, S. & Santillan, R. (1998). Inorg. Chem. 37, 1679-1692.]; Böhme & Fels, 2008a[Böhme, U. & Fels, S. (2008a). Acta Cryst. E64, o14.],b[Böhme, U. & Fels, S. (2008b). Acta Cryst. E64, o178.]). The stabilization of salicyl­idene-imines by `resonance-assisted hydrogen bonding' has been discussed previously (Hökelek et al., 2004[Hökelek, T., Bilge, S., Demiriz, Ş., Özgüç, B. & Kılıç, Z. (2004). Acta Cryst. C60, o803-o805.]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H2⋯O1 0.93 (2) 1.84 (2) 2.6065 (18) 138.1 (17)
O2—H9⋯O1i 0.79 (3) 1.81 (3) 2.5817 (18) 163 (3)
C1—H1⋯O4ii 0.93 2.32 3.220 (2) 162
Symmetry codes: (i) [-x+1, -y+2, -z]; (ii) [-x-1, -y+1, -z].
[Figure 1]
Figure 1
The mol­ecular structure of the title compound, drawn with 50% probability displacement ellipsoids.

In the crystal, the mol­ecule forms dimers via pairwise O2—H9⋯O1 hydrogen bonds. An inter­molecular C—H⋯O short contact (H⋯O = 2.32 Å) to one of the O atoms of the nitro group is also present.

Synthesis and crystallization

To 2-amino-4-methyl­phenol (1.13 g, 9.18 mmol) dissolved in ethanol (80 ml) was added 2-hy­droxy-5-nitro­benzaldehyde (1.53 g, 9.18 mmol) in ethanol (20 ml). An orange precipitate appeared after addition. The resulting suspension was heated at reflux temperature for 2 h. The precipitate was filtered off and washed with ethanol. After drying, the product was purified by recrystallization from ethanol solution. Yellow solid (2.21 g, 88.4%, m.p. 536 K). NMR (DMSO, 300 K, TMS): 1H: δ = 15.76, 10.17 (s, OH, NH, 2H), 9.31 (s, CH—N, 1H), 8.59–6.86 (m, CHar (ar = aromatic) 6H), 2.28 (s, Ar—CH3, 3H); 13C: 172.8 (C3), 158.9 (C1), 148.1 (C9), 136.6 (C6), 130.4, 129.8, 129.1, 128.7, 128.6, 120.6, 118.8, 116.4, 116.3 (9 signals for aromatic C), 20.1 (C14).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. The methyl group at C14 is rotationally disordered over two orientations in a 0.59 (5):0.41 (5) ratio.

Table 2
Experimental details

Crystal data
Chemical formula C14H12N2O4
Mr 272.26
Crystal system, space group Monoclinic, P21/c
Temperature (K) 303
a, b, c (Å) 6.5499 (3), 7.6232 (3), 25.6211 (11)
β (°) 96.216 (1)
V3) 1271.77 (9)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.11
Crystal size (mm) 0.47 × 0.38 × 0.12
 
Data collection
Diffractometer Bruker SMART CCD
Absorption correction
No. of measured, independent and observed [I > 2σ(I)] reflections 11875, 2504, 1776
Rint 0.023
(sin θ/λ)max−1) 0.617
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.114, 1.04
No. of reflections 2504
No. of parameters 191
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.16, −0.17
Computer programs: SMART and SAINT (Bruker, 2004[Bruker (2004). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2017/1 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]) and ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]).

Structural data


Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SMART (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2017/1 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL2017/1 (Sheldrick, 2015).

6-[(2-Hydroxy-5-methylanilino)methylidene]-4-nitrocyclohexa-2,4-dien-1-one top
Crystal data top
C14H12N2O4Dx = 1.422 Mg m3
Mr = 272.26Melting point: 536 K
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 6.5499 (3) ÅCell parameters from 5292 reflections
b = 7.6232 (3) Åθ = 2.7–30.2°
c = 25.6211 (11) ŵ = 0.11 mm1
β = 96.216 (1)°T = 303 K
V = 1271.77 (9) Å3Prism, yellow
Z = 40.47 × 0.38 × 0.12 mm
F(000) = 568
Data collection top
Bruker SMART CCD
diffractometer
1776 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.023
Graphite monochromatorθmax = 26.0°, θmin = 2.8°
phi and ω scansh = 58
11875 measured reflectionsk = 99
2504 independent reflectionsl = 3127
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)] = 0.041Hydrogen site location: mixed
wR(F2) = 0.114H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0502P)2 + 0.2714P]
where P = (Fo2 + 2Fc2)/3
2504 reflections(Δ/σ)max < 0.001
191 parametersΔρmax = 0.16 e Å3
0 restraintsΔρmin = 0.17 e Å3
Special details top

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.

Refinement. Hydrogen atoms bonded to C were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.93 Å for Csp2, and 0.96 Å for CH3. Uiso(H) = xUeq(C), where x = 1.2 for Csp2 and 1.5 for CH3. The hydrogen atoms at N1 and O2 (H2 and H9) were located by difference Fourier synthesis and freely refined.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.19636 (18)0.85732 (19)0.05759 (5)0.0666 (4)
O20.5013 (2)0.9258 (2)0.05845 (5)0.0669 (4)
H90.596 (4)0.991 (3)0.0647 (10)0.093 (9)*
N10.1333 (2)0.79690 (18)0.03950 (5)0.0468 (4)
H20.215 (3)0.835 (3)0.0143 (8)0.077 (6)*
N20.5557 (2)0.5515 (2)0.11991 (6)0.0576 (4)
O30.6215 (2)0.5556 (2)0.16650 (6)0.0845 (5)
O40.6495 (2)0.48027 (19)0.08672 (6)0.0740 (4)
C10.0438 (2)0.7351 (2)0.02029 (6)0.0481 (4)
H10.1339790.6966280.0434930.058*
C20.1063 (2)0.7235 (2)0.03427 (6)0.0447 (4)
C30.0234 (2)0.7870 (2)0.07240 (6)0.0479 (4)
C40.0523 (3)0.7664 (3)0.12613 (7)0.0563 (5)
H40.0278530.8047160.1517110.068*
C50.2369 (3)0.6928 (2)0.14126 (7)0.0541 (5)
H50.2824850.6819300.1767670.065*
C60.3600 (2)0.6328 (2)0.10331 (7)0.0471 (4)
C70.2971 (2)0.6483 (2)0.05097 (7)0.0478 (4)
H70.3810070.6086900.0263860.057*
C80.2130 (2)0.8135 (2)0.09270 (6)0.0456 (4)
C90.4090 (3)0.8863 (2)0.10173 (7)0.0510 (4)
C100.4949 (3)0.9106 (3)0.15292 (7)0.0634 (5)
H100.6248750.9601500.1596240.076*
C110.3879 (3)0.8614 (3)0.19404 (7)0.0684 (6)
H110.4468150.8797030.2282880.082*
C120.1941 (3)0.7851 (3)0.18568 (7)0.0599 (5)
C130.1080 (3)0.7624 (2)0.13445 (6)0.0526 (4)
H130.0217050.7123810.1278630.063*
C140.0811 (4)0.7261 (4)0.23108 (8)0.0869 (7)
H14A0.1698040.6536760.2542830.130*0.59 (5)
H14B0.0385120.6603560.2179050.130*0.59 (5)
H14C0.0402130.8269660.2498520.130*0.59 (5)
H14D0.1418160.7800540.2628970.130*0.41 (5)
H14E0.0902800.6008900.2344410.130*0.41 (5)
H14F0.0605920.7600540.2247010.130*0.41 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0548 (7)0.0944 (10)0.0521 (8)0.0311 (7)0.0125 (6)0.0061 (7)
O20.0594 (8)0.0874 (10)0.0547 (8)0.0275 (8)0.0103 (6)0.0008 (7)
N10.0490 (8)0.0530 (9)0.0390 (8)0.0094 (7)0.0082 (6)0.0016 (6)
N20.0509 (8)0.0630 (10)0.0572 (10)0.0064 (7)0.0016 (7)0.0013 (8)
O30.0695 (9)0.1175 (13)0.0616 (10)0.0193 (8)0.0147 (7)0.0000 (8)
O40.0583 (8)0.0872 (10)0.0757 (10)0.0265 (7)0.0040 (7)0.0075 (8)
C10.0475 (9)0.0534 (10)0.0446 (10)0.0096 (8)0.0108 (7)0.0013 (8)
C20.0462 (9)0.0476 (10)0.0411 (9)0.0056 (7)0.0074 (7)0.0032 (7)
C30.0466 (9)0.0539 (10)0.0446 (9)0.0076 (8)0.0107 (7)0.0055 (8)
C40.0561 (10)0.0722 (12)0.0427 (10)0.0119 (9)0.0145 (8)0.0019 (9)
C50.0567 (10)0.0636 (12)0.0414 (10)0.0032 (9)0.0036 (8)0.0037 (8)
C60.0439 (8)0.0481 (10)0.0487 (10)0.0033 (7)0.0021 (7)0.0025 (8)
C70.0453 (9)0.0518 (10)0.0476 (10)0.0073 (7)0.0111 (7)0.0024 (8)
C80.0514 (9)0.0459 (9)0.0393 (9)0.0042 (7)0.0044 (7)0.0007 (7)
C90.0520 (9)0.0543 (11)0.0470 (10)0.0077 (8)0.0064 (8)0.0025 (8)
C100.0543 (10)0.0788 (14)0.0546 (12)0.0118 (10)0.0058 (8)0.0012 (10)
C110.0759 (13)0.0842 (15)0.0423 (11)0.0087 (11)0.0059 (9)0.0016 (10)
C120.0717 (12)0.0652 (12)0.0428 (10)0.0087 (10)0.0062 (8)0.0012 (9)
C130.0566 (10)0.0566 (11)0.0452 (10)0.0116 (8)0.0081 (8)0.0013 (8)
C140.1101 (18)0.1055 (18)0.0469 (12)0.0257 (15)0.0171 (12)0.0029 (12)
Geometric parameters (Å, º) top
O1—C31.2734 (19)C6—C71.365 (2)
O2—C91.353 (2)C7—H70.9300
O2—H90.79 (3)C8—C131.389 (2)
N1—C11.298 (2)C8—C91.394 (2)
N1—C81.411 (2)C9—C101.383 (3)
N1—H20.93 (2)C10—C111.379 (3)
N2—O31.225 (2)C10—H100.9300
N2—O41.2280 (18)C11—C121.392 (3)
N2—C61.446 (2)C11—H110.9300
C1—C21.416 (2)C12—C131.382 (2)
C1—H10.9300C12—C141.513 (3)
C2—C71.399 (2)C13—H130.9300
C2—C31.446 (2)C14—H14A0.9600
C3—C41.420 (2)C14—H14B0.9600
C4—C51.351 (2)C14—H14C0.9600
C4—H40.9300C14—H14D0.9600
C5—C61.405 (2)C14—H14E0.9600
C5—H50.9300C14—H14F0.9600
C9—O2—H9112.4 (18)C13—C8—N1123.79 (15)
C1—N1—C8128.37 (14)C9—C8—N1115.70 (14)
C1—N1—H2114.1 (13)O2—C9—C10125.12 (16)
C8—N1—H2117.6 (13)O2—C9—C8115.95 (15)
O3—N2—O4122.47 (16)C10—C9—C8118.92 (15)
O3—N2—C6118.86 (15)C11—C10—C9119.98 (17)
O4—N2—C6118.67 (15)C11—C10—H10120.0
N1—C1—C2123.24 (14)C9—C10—H10120.0
N1—C1—H1118.4C10—C11—C12121.78 (18)
C2—C1—H1118.4C10—C11—H11119.1
C7—C2—C1118.74 (14)C12—C11—H11119.1
C7—C2—C3120.10 (14)C13—C12—C11118.04 (17)
C1—C2—C3121.17 (14)C13—C12—C14120.65 (18)
O1—C3—C4122.77 (14)C11—C12—C14121.31 (18)
O1—C3—C2120.57 (15)C12—C13—C8120.75 (16)
C4—C3—C2116.67 (14)C12—C13—H13119.6
C5—C4—C3122.11 (15)C8—C13—H13119.6
C5—C4—H4118.9C12—C14—H14A109.5
C3—C4—H4118.9C12—C14—H14B109.5
C4—C5—C6119.96 (16)H14A—C14—H14B109.5
C4—C5—H5120.0C12—C14—H14C109.5
C6—C5—H5120.0H14A—C14—H14C109.5
C7—C6—C5121.13 (15)H14B—C14—H14C109.5
C7—C6—N2119.33 (15)C12—C14—H14D109.5
C5—C6—N2119.53 (15)C12—C14—H14E109.5
C6—C7—C2120.03 (14)H14D—C14—H14E109.5
C6—C7—H7120.0C12—C14—H14F109.5
C2—C7—H7120.0H14D—C14—H14F109.5
C13—C8—C9120.51 (15)H14E—C14—H14F109.5
C8—N1—C1—C2179.40 (16)C1—C2—C7—C6178.99 (16)
N1—C1—C2—C7177.42 (16)C3—C2—C7—C60.7 (3)
N1—C1—C2—C32.3 (3)C1—N1—C8—C130.4 (3)
C7—C2—C3—O1179.29 (16)C1—N1—C8—C9179.56 (17)
C1—C2—C3—O11.0 (3)C13—C8—C9—O2177.63 (16)
C7—C2—C3—C40.8 (2)N1—C8—C9—O22.4 (2)
C1—C2—C3—C4178.95 (16)C13—C8—C9—C101.5 (3)
O1—C3—C4—C5179.43 (18)N1—C8—C9—C10178.44 (16)
C2—C3—C4—C50.6 (3)O2—C9—C10—C11178.40 (19)
C3—C4—C5—C60.4 (3)C8—C9—C10—C110.7 (3)
C4—C5—C6—C70.4 (3)C9—C10—C11—C120.7 (3)
C4—C5—C6—N2178.90 (16)C10—C11—C12—C131.2 (3)
O3—N2—C6—C7171.96 (17)C10—C11—C12—C14177.9 (2)
O4—N2—C6—C78.3 (2)C11—C12—C13—C80.4 (3)
O3—N2—C6—C58.8 (3)C14—C12—C13—C8178.81 (19)
O4—N2—C6—C5170.98 (16)C9—C8—C13—C121.0 (3)
C5—C6—C7—C20.5 (3)N1—C8—C13—C12178.96 (17)
N2—C6—C7—C2178.75 (15)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H2···O10.93 (2)1.84 (2)2.6065 (18)138.1 (17)
O2—H9···O1i0.79 (3)1.81 (3)2.5817 (18)163 (3)
C1—H1···O4ii0.932.323.220 (2)162
Symmetry codes: (i) x+1, y+2, z; (ii) x1, y+1, z.
 

Funding information

Funding for this research was provided by: Open Access Funding by the Publication Fund of the TU Bergakademie Freiberg.

References

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