6-(2-Hydroxy­anilinomethyl­ene)-4-nitro­cyclo­hexa-2,4-dien-1-one

The molecule of the title compound, C₁₃H₁₀N₂O₄, is nearly planar with a dihedral angle between the two aromatic rings of 2.24 (9)°. The NH group forms an intramolecular hydrogen bond with the carbonyl O atom. The mol­ecules form dimers about inversion centers in the crystal structure via inter­molecular O—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 303 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.042
• wR factor = 0.115
• Data-to-parameter ratio = 13.1

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S1. Comment

We have been working on silicon and titanium complexes with tridentate O,N,O-ligands (Böhme & Günther, 2006; Böhme, Wiesner & Günther, 2006; Böhme & Günther, 2007). The title compound, (I), was prepared in order to extend the series of available ligands. The preparation of (I) was performed according to the methods described in the literature for the parent compound salicyclidene-o-aminophenol ("salopH₂") (Freeman & White, 1956; Pettinari et al., 2001). The molecule of (I) is nearly planar with a dihedral angle between the two aromatic rings of 2.24 (9)°. The atom H2 forms an intramolecular hydrogen bond between the phenolic oxygen atom O1 and N1 of the azomethine unit. The hydrogen atom H2 is localized at N1. This hints to the presence of the keto-amine form. The presence of a quinoidal structure is further supported by the shortening of the bond O1—C3 to 1.276 (2) Å and the lengthening of the adjacent C—C bonds in the phenyl ring [C2—C3 1.443 (2), C3—C4 1.423 (2) Å] (Nazir et al., 2000). There are few structure reports of Schiff-bases with oxygen in ortho-position where the intramolecular bridging hydrogen atom is localized at the nitrogen atom (e.g. Pradeep, 2005; Dubs et al., 2000; Hopfl et al., 1998). The molecules form dimers about inversion centers in the crystal lattice via intermolecular O2—H9···O1 hydrogen bonds. Unconventional hydrogen bonds of the type C—H···O are also present in the structure.

Related literature

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; Calligaris & Randaccio, 1987; Pettinari et al., 2001; Hernández-Molina & Mederos, 2004). For related literature, see: Böhme & Günther (2006, 2007); Böhme, Wiesner & Günther (2006); Dubs et al. (2000); Hopfl et al. (1998); Nazir et al. (2000); Pradeep (2005).

S2. Experimental

To 2-aminophenol (2.12 g, 19.4 mmol) dissolved in ethanol (100 ml) was added 2-hydroxy-5-nitrobenzaldehyde (3.24 g, 19.4 mmol) in ethanol (50 ml). The resulting yellow suspension was refluxed for 1 h. The precipitate was filtered off and washed with ethanol. After drying, the product was purified by recrystallization from ethanol afforded yellow crystals of (I) (3.81 g, 76.2%, m.p. 528 K).

S3. Refinement

Hydrogen atoms bonded to C, N, and O were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.93, O—H = 0.82, and N—H = 0.86 Å and U_iso(H) values of 1.2U_eq(C/N) and 1.5U_eq(O).

Computing details

Data collection: SMART (Bruker, 2004); cell refinement: SMART (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. The molecular structure of (I) drawn with 50% probability displacement ellipsoids.

6-(2-Hydroxyanilinomethylene)-4-nitrocyclohexa-2,4-dien-1-one

Crystal data

C13H10N2O4	F(000) = 536
Mr = 258.23	Dx = 1.455 Mg m^−3
Monoclinic, P21/n	Melting point: 528 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 6.3445 (3) Å	Cell parameters from 3470 reflections
b = 23.7378 (10) Å	θ = 3.3–28.2°
c = 7.8450 (3) Å	µ = 0.11 mm^−1
β = 93.79 (1)°	T = 303 K
V = 1178.90 (9) Å^3	Prism, yellow
Z = 4	0.3 × 0.25 × 0.12 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1523 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.025
Graphite monochromator	θmax = 26.0°, θmin = 1.7°
φ and ω scans	h = −7→7
9006 measured reflections	k = −29→29
2273 independent reflections	l = −8→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.115	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0575P)^2 + 0.0914P] where P = (Fo^2 + 2Fc^2)/3
2273 reflections	(Δ/σ)max < 0.001
174 parameters	Δρmax = 0.13 e Å^−3
0 restraints	Δρmin = −0.17 e Å^−3

Special details

Experimental. NMR (DMSO, 300 K, TMS): ¹H: δ=15.73, 10.38 (s, OH, 2H), 9.31 (s, CH—N, 1H), 8.18–6.89 (m, CH_aromatic, 7H); ¹³C: 172.3 (C3), 159.2 (C1), 150.4 (C9), 136.7 (C6), 130.3, 129.8, 129.2, 128.6, 120.4, 119.8, 118.7, 116.5, 116.4 (9 signals for aromatic C).

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.2616 (2)	−0.05887 (5)	0.83707 (17)	0.0600 (4)
O2	0.0255 (2)	0.06605 (5)	0.94717 (17)	0.0584 (4)
H9	−0.0597	0.0732	1.0184	0.088*
O3	1.0149 (2)	−0.17158 (6)	0.5016 (2)	0.0762 (5)
O4	1.0816 (2)	−0.08467 (6)	0.45149 (17)	0.0632 (4)
N1	0.3820 (2)	0.04592 (6)	0.81241 (17)	0.0432 (4)
H2	0.2899	0.0216	0.8403	0.068 (6)*
N2	0.9733 (2)	−0.12137 (7)	0.51253 (19)	0.0513 (4)
C1	0.5465 (3)	0.02556 (7)	0.7441 (2)	0.0449 (4)
H1	0.6502	0.0506	0.7131	0.054*
C2	0.5767 (3)	−0.03237 (7)	0.7143 (2)	0.0409 (4)
C3	0.4260 (3)	−0.07387 (7)	0.7635 (2)	0.0447 (4)
C4	0.4701 (3)	−0.13107 (8)	0.7250 (2)	0.0524 (5)
H4	0.3761	−0.1589	0.7549	0.063*
C5	0.6451 (3)	−0.14622 (7)	0.6460 (2)	0.0501 (5)
H5	0.6701	−0.1840	0.6228	0.060*
C6	0.7890 (3)	−0.10481 (7)	0.5989 (2)	0.0427 (4)
C7	0.7560 (3)	−0.04926 (7)	0.6329 (2)	0.0435 (4)
H7	0.8532	−0.0225	0.6018	0.052*
C8	0.3340 (3)	0.10296 (7)	0.8472 (2)	0.0425 (4)
C9	0.1443 (3)	0.11220 (7)	0.9216 (2)	0.0452 (4)
C10	0.0879 (3)	0.16669 (8)	0.9629 (2)	0.0572 (5)
H10	−0.0386	0.1734	1.0130	0.069*
C11	0.2198 (3)	0.21088 (8)	0.9297 (3)	0.0672 (6)
H11	0.1823	0.2474	0.9584	0.081*
C12	0.4076 (3)	0.20149 (8)	0.8538 (3)	0.0676 (6)
H12	0.4950	0.2317	0.8312	0.081*
C13	0.4653 (3)	0.14742 (8)	0.8116 (3)	0.0563 (5)
H13	0.5908	0.1410	0.7600	0.068*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0501 (8)	0.0584 (8)	0.0747 (9)	−0.0075 (6)	0.0276 (7)	−0.0052 (7)
O2	0.0563 (8)	0.0520 (8)	0.0701 (10)	−0.0084 (6)	0.0275 (7)	−0.0030 (6)
O3	0.0705 (10)	0.0513 (8)	0.1096 (13)	0.0168 (7)	0.0280 (9)	0.0042 (8)
O4	0.0589 (8)	0.0617 (9)	0.0722 (9)	0.0009 (7)	0.0275 (7)	0.0066 (7)
N1	0.0419 (8)	0.0442 (8)	0.0447 (9)	−0.0064 (7)	0.0113 (7)	−0.0019 (6)
N2	0.0481 (9)	0.0522 (10)	0.0544 (10)	0.0065 (7)	0.0089 (8)	0.0050 (7)
C1	0.0409 (10)	0.0492 (10)	0.0452 (10)	−0.0066 (8)	0.0090 (8)	0.0009 (8)
C2	0.0395 (9)	0.0459 (10)	0.0376 (9)	−0.0025 (7)	0.0056 (8)	0.0008 (7)
C3	0.0409 (10)	0.0514 (11)	0.0423 (10)	−0.0053 (8)	0.0062 (8)	−0.0015 (8)
C4	0.0474 (11)	0.0470 (10)	0.0634 (13)	−0.0100 (8)	0.0090 (9)	0.0008 (9)
C5	0.0507 (11)	0.0416 (10)	0.0583 (12)	−0.0012 (8)	0.0056 (9)	−0.0007 (8)
C6	0.0406 (9)	0.0481 (10)	0.0400 (10)	0.0018 (8)	0.0072 (8)	0.0035 (8)
C7	0.0401 (9)	0.0465 (10)	0.0447 (10)	−0.0045 (7)	0.0077 (8)	0.0043 (8)
C8	0.0454 (10)	0.0401 (9)	0.0426 (10)	−0.0027 (7)	0.0058 (8)	−0.0017 (7)
C9	0.0435 (10)	0.0468 (10)	0.0460 (10)	−0.0032 (8)	0.0076 (8)	0.0031 (8)
C10	0.0534 (12)	0.0527 (11)	0.0665 (13)	0.0060 (9)	0.0124 (10)	−0.0029 (9)
C11	0.0737 (14)	0.0431 (11)	0.0862 (16)	0.0043 (10)	0.0163 (12)	−0.0049 (10)
C12	0.0694 (14)	0.0470 (11)	0.0883 (16)	−0.0121 (10)	0.0195 (12)	−0.0014 (10)
C13	0.0525 (11)	0.0510 (11)	0.0675 (13)	−0.0068 (9)	0.0183 (10)	−0.0023 (9)

Geometric parameters (Å, º)

O1—C3	1.276 (2)	C4—H4	0.9300
O2—C9	1.352 (2)	C5—C6	1.408 (2)
O2—H9	0.8200	C5—H5	0.9300
O3—N2	1.225 (2)	C6—C7	1.364 (2)
O4—N2	1.226 (2)	C7—H7	0.9300
N1—C1	1.298 (2)	C8—C13	1.384 (2)
N1—C8	1.418 (2)	C8—C9	1.389 (2)
N1—H2	0.8600	C9—C10	1.386 (3)
N2—C6	1.444 (2)	C10—C11	1.378 (3)
C1—C2	1.410 (2)	C10—H10	0.9300
C1—H1	0.9300	C11—C12	1.385 (3)
C2—C7	1.399 (2)	C11—H11	0.9300
C2—C3	1.443 (2)	C12—C13	1.381 (3)
C3—C4	1.423 (2)	C12—H12	0.9300
C4—C5	1.356 (2)	C13—H13	0.9300
C9—O2—H9	109.5	C7—C6—N2	119.64 (15)
C1—N1—C8	128.60 (15)	C5—C6—N2	119.49 (16)
C1—N1—H2	115.7	C6—C7—C2	120.42 (16)
C8—N1—H2	115.7	C6—C7—H7	119.8
O3—N2—O4	122.35 (15)	C2—C7—H7	119.8
O3—N2—C6	118.86 (15)	C13—C8—C9	120.92 (16)
O4—N2—C6	118.79 (15)	C13—C8—N1	123.32 (16)
N1—C1—C2	123.60 (16)	C9—C8—N1	115.76 (14)
N1—C1—H1	118.2	O2—C9—C10	124.47 (16)
C2—C1—H1	118.2	O2—C9—C8	116.19 (15)
C7—C2—C1	118.58 (16)	C10—C9—C8	119.34 (16)
C7—C2—C3	119.95 (15)	C11—C10—C9	119.77 (18)
C1—C2—C3	121.46 (16)	C11—C10—H10	120.1
O1—C3—C4	122.72 (16)	C9—C10—H10	120.1
O1—C3—C2	120.43 (16)	C10—C11—C12	120.64 (18)
C4—C3—C2	116.85 (15)	C10—C11—H11	119.7
C5—C4—C3	121.92 (17)	C12—C11—H11	119.7
C5—C4—H4	119.0	C13—C12—C11	120.12 (18)
C3—C4—H4	119.0	C13—C12—H12	119.9
C4—C5—C6	119.99 (17)	C11—C12—H12	119.9
C4—C5—H5	120.0	C12—C13—C8	119.19 (18)
C6—C5—H5	120.0	C12—C13—H13	120.4
C7—C6—C5	120.86 (16)	C8—C13—H13	120.4
C8—N1—C1—C2	−179.49 (15)	N2—C6—C7—C2	179.08 (15)
N1—C1—C2—C7	177.23 (16)	C1—C2—C7—C6	−178.79 (16)
N1—C1—C2—C3	−1.9 (3)	C3—C2—C7—C6	0.3 (3)
C7—C2—C3—O1	−179.67 (16)	C1—N1—C8—C13	−0.5 (3)
C1—C2—C3—O1	−0.6 (3)	C1—N1—C8—C9	179.91 (17)
C7—C2—C3—C4	−0.1 (2)	C13—C8—C9—O2	178.46 (16)
C1—C2—C3—C4	179.00 (15)	N1—C8—C9—O2	−1.9 (2)
O1—C3—C4—C5	179.64 (17)	C13—C8—C9—C10	−1.0 (3)
C2—C3—C4—C5	0.1 (3)	N1—C8—C9—C10	178.64 (16)
C3—C4—C5—C6	−0.3 (3)	O2—C9—C10—C11	−179.28 (18)
C4—C5—C6—C7	0.5 (3)	C8—C9—C10—C11	0.1 (3)
C4—C5—C6—N2	−179.10 (16)	C9—C10—C11—C12	0.6 (3)
O3—N2—C6—C7	171.10 (16)	C10—C11—C12—C13	−0.4 (3)
O4—N2—C6—C7	−9.5 (2)	C11—C12—C13—C8	−0.4 (3)
O3—N2—C6—C5	−9.3 (2)	C9—C8—C13—C12	1.1 (3)
O4—N2—C6—C5	170.09 (16)	N1—C8—C13—C12	−178.47 (17)
C5—C6—C7—C2	−0.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2···O1	0.86	1.92	2.613 (2)	137
O2—H9···O1^i	0.82	1.80	2.573 (2)	157
C1—H1···O4^ii	0.93	2.35	3.220 (2)	156

Symmetry codes: (i) −x, −y, −z+2; (ii) −x+2, −y, −z+1.