(E)-2-[(2-Hydr­oxy-5-nitro­phen­yl)iminiometh­yl]phenolate

Abstract

In the title mol­ecule, C₁₃H₁₀N₂O₄, the dihedral angle between the mean planes of the benzene and phenolate rings is 21.6 (4)°. The nitro O atoms are twisted slightly out of the plane of the ring to which the nitro group is attached [dihedral angle 8.4 (3)°]. The amine group forms an intra­molecular hydrogen bond with both nearby O atoms. An extended π delocalization throughout the entire mol­ecule exists producing a zwitterionic effect in this region of the mol­ecule. The shortened C—O bond [1.2997 (15) Å] in concert with the slightly longer C—OH bond [1.3310 (16) Å] provide evidence for this effect. The crystal packing is influenced by strong inter­molecular O—H⋯O hydrogen bonding. As a result, mol­ecules are linked into an infinite zigzag chain running along the b axis. A MOPAC PM3 calculation provides support to these observations.

Related literature

For related structures, see: Ersanlı et al. (2003 ▶); Odabaşoğlu et al. (2006 ▶); Jasinski et al. (2007 ▶); Elerman et al. (1995 ▶); Hijji et al. (2008 ▶, 2009 ▶). For the application of Schiff bases in organic synthesis, see: Barba et al. (2001 ▶); Rodriguez et al. (2005 ▶). For details of the MOPAC PM3 calculation, see: Schmidt & Polik (2007 ▶).

Experimental

Crystal data

• C₁₃H₁₀N₂O₄

• M _r = 258.23

• Monoclinic,

• a = 7.3949 (3) Å

• b = 9.1058 (4) Å

• c = 17.2734 (6) Å

• β = 96.387 (4)°

• V = 1155.91 (8) ų

• Z = 4

• Mo Kα radiation

• μ = 0.11 mm⁻¹

• T = 296 (2) K

• 0.45 × 0.36 × 0.21 mm

Data collection

• Oxford Diffraction Gemini R diffractometer

• Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 ▶) T _min = 0.950, T _max = 0.977

• 16362 measured reflections

• 3889 independent reflections

• 2071 reflections with I > 2σ(I)

• R _int = 0.045

Refinement

• R[F ² > 2σ(F ²)] = 0.052

• wR(F ²) = 0.161

• S = 1.01

• 3889 reflections

• 173 parameters

• H-atom parameters constrained

• Δρ_max = 0.36 e Å⁻³

• Δρ_min = −0.23 e Å⁻³

Data collection: CrysAlisPro (Oxford Diffraction, 2007 ▶); cell refinement: CrysAlisPro; data reduction: CrysAlisRed (Oxford Diffraction, 2007 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O4i	0.82	1.72	2.5407 (13)	175
N2—H2B⋯O4	0.86	1.91	2.5973 (15)	135
N2—H2B⋯O1	0.86	2.34	2.6532 (14)	102
C2—H2A⋯O4i	0.93	2.60	3.2233 (18)	125
C13—H13A⋯O2ii	0.93	2.65	3.5555 (19)	163

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

Schiff bases have extensive application in industry. Much interest in these compounds and their complexes is due to their anti-tumor activities. The boronate complex derivative of the title compound (Barba et al. 2001) displays it in the phenol-imine form, which can undergo an imine Diels-Alder reaction to produce a 3,4-dihydroquinoline (Rodriguez et al., 2005). Compounds of this type can also be used as anion sensors in acetonitrile (Hijji et al., 2008) and tend to exist in the keto-amine form, which is generally favored over the phenol-imine form in the solid state. While the keto-amine tautomer is commonly produced in these complexes (Ersanlı et al., 2003; Odabaşoğlu et al., 2006; Elerman et al., 1995; Jasinski et al., 2007), the title compound adapts a phenol-iminio tautomer as the stable form which is confirmed by the X-ray data and in agreement with that found via NMR data in DMSO solution. The stability of this form may be enhanced by the electronic effect of the nitro group. The dark color in the solid state is generally an indication of increased conjugation, while the yellow colored solutions, as in acetonitrile or anhydrous DMSO, may be due to conversion to the phenol-iminio tautomer.

The title molecule, C₁₃H₁₀N₂O₄, consists of a 2-hydroxy-5-nitrophenyliminio group and a phenolate group bonded to a methylene carbon atom with both of the planar six-membered rings twisted from the plane of the molecule. The dihedral angle between the mean planes of the phenyl and phenolate rings measures 21.6 (4)°. The nitro oxygen atoms are twisted slightly out of the plane of the molecule [torsion angles = 170.80 (13) (O2—N1—C4—C5); -7.5 (2)° (O3—N1—C4—C5); -5.8 (2)° (O2—N1—C4—C3); 175.92 (14)° (O3—N1—C4—C3)]. The phenolate (O4) and hydroxy (O1) oxygen atoms are essentially in the plane of the molecule [torsion angles = -179.51 (13)° (O4—C9—C10—C11); -3.2 (2)° (O4—C9—C8—C7); -178.63 (14)° (O1—C1—C2—C3); 178.83 (12)° (O1—C1—C6—C5)]. The iminio group forms an intramolecular hydrogen bond with each of the nearby oxygen atoms (O1 and O4) (see Fig. 1 and Table 1). There appears to be an extended π delocalization effect throughout the entire molecule producing a zwitterionic effect in this region of the molecule similar to that seen in a close structurally related dinitro compound (Hijji et al., 2009). The shortened C9—O4 bond (1.2997 (15) Å in concert with the slightly longer C1—O1 bond (1.3310 (16) Å) provide structural evidence of this effect in a similar fashion.

Crystal packing is influenced by extensive strong intermolecular O—H···O hydrogen bonding between the phenolate and hydroxy oxygen atoms (O4 & O1) and their respective hydrogen atoms within the π delocalized region (O1—H10···O4; 2.540 (7) Å) of the molecule. Additional weak intermolecular C—H···O hydrogen bond interactions occur involving the phenyl (C2) and phenolate (C13) groups, respectively. All of the hydrogen bond interactions are summarized in Table 1. A s a result the molecules are linked into an infinite polymeric chain diagonally along the [101] plane of the unit cell in an alternate inverted pattern (Fig. 2). In addition, weak Cg2–Cg2 (3.895 (2) Å; slippage = 1.09 (2)°; -x, 2 - y, -z) π-π stacking ring interactions and N1–O2···Cg2 π-ring interactions (3.648 (4) Å; x, -1 + y, z) also occur where Cg2 = center of gravity of the C8–C13 ring.

After a MOPAC PM3 calculation [Parameterized Model 3 approximation together with the Hartree-Fock closed-shell (restricted) wavefunction was used and minimizations were teminnated at an r.m.s. gradient of less than 0.01 kJ mol^-1 Å^-1] of the zwitterionic form with WebMO Pro (Schmidt & Polik, 2007), the mean planes between the phenyl and phenolate rings changes to 3.7 (7)°, producing a significantly less twisted, nearly planar, molecule than that observed in the crystalline environment. It is apparent that the extensive hydrogen bonding, π-π stacking and π-ring intermolecular interactions significantly influence crystal packing with this molecule.

Experimental

2-Amino-4-nitrophenol (0.15 g, 1 mmol) and salicylaldehyde (0.12 g, 1 mmol) were mixed neat in a loosely capped vial, forming a light orange solid. The mixture was heated at full power in a conventional spacemaker II microwave oven for two minutes forming a deep orange product. The reaction mixture was recrystallized from a 1:1 mixture (v:v) of methanol and diethyl ether affording 0.18 g, 67% yield of the title compound as dark purple crystals. The physical data is in agreement with literature (Barba et al., 2001), mp 505–508 K, GC/MS, m/z: 258 (M⁺), 211,165, 77, 51. ¹H-NMR (400 MHz, DMSO-d6) δ (p.p.m.): 13.21(s, 1H), 11.41(s, 1H), 9.10(s, 1H), 8.28(d, J = 2.7 Hz, 1H), 8.07 (dd, J = 8.87, 2.7 Hz, 1H), 7.70 (dd, J = 7.65, 1.3 Hz, 1H), 7.44 (dt, J = 7.6,1.5 Hz, 1H), 7.14 (d, J = 9.03 Hz, 1H), 6.98 (t, J = 7.7, H), 6.96 (d, J = 8.5 Hz, 1H). ¹³C-NMR (100 MHz, DMSO-d₆) δ (p.p.m.): 164.4 (CH), 160.5 (C), 157.6 (C), 139.9 (C), 135.7 (C), 133.5 (CH), 132.7 (CH), 123.7 (CH), 119.4 (CH), 117.2 (CH), 116.7 (CH), 116.3 (CH), 115.3 (CH).

Refinement

All H atoms could be seen in a difference fourier map. Nevertheless, they were placed in their calculated positions and then refined using the riding model with O—H = 0.82, N—H = 0.86 and C—H = 0.93 Å, and with U_iso(H) = 1.18–1.20U_eq(C, N, O).

Figures

Fig. 1.

The molecular structure of C13H10N2O4, showing the atom numbering scheme and 50% probability displacement ellipsoids. Dashed lines indicate intramolecular N–H···O hydrogen bonds.

Fig. 2.

The molecular packing for C13H10N2O4 viewed down the b axis. Dashed lines indicate intermolecular O–H···O, C–H···O and intramolecular N–H···O hydrogen bonds.

Crystal data

C13H10N2O4	F(000) = 536
Mr = 258.23	Dx = 1.484 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5321 reflections
a = 7.3949 (3) Å	θ = 4.6–32.6°
b = 9.1058 (4) Å	µ = 0.11 mm−1
c = 17.2734 (6) Å	T = 296 K
β = 96.387 (4)°	Prism, yellow
V = 1155.91 (8) Å3	0.45 × 0.36 × 0.21 mm
Z = 4

Data collection

Oxford Diffraction Gemini R diffractometer	3889 independent reflections
Radiation source: fine-focus sealed tube	2071 reflections with I > 2σ(I)
graphite	Rint = 0.045
Detector resolution: 10.5081 pixels mm-1	θmax = 32.5°, θmin = 4.6°
φ and ω scans	h = −10→11
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007)	k = −12→13
Tmin = 0.950, Tmax = 0.977	l = −25→24
16362 measured reflections

Refinement

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) = 0.161	H-atom parameters constrained
S = 1.01	w = 1/[σ2(Fo2) + (0.0893P)2] where P = (Fo2 + 2Fc2)/3
3889 reflections	(Δ/σ)max < 0.001
173 parameters	Δρmax = 0.36 e Å−3
0 restraints	Δρmin = −0.23 e Å−3

Special details

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	0.07674 (16)	0.78106 (11)	0.74658 (6)	0.0506 (3)
H1O	0.0213	0.8253	0.7779	0.061*
O2	0.56661 (19)	1.27359 (14)	0.63179 (8)	0.0696 (4)
O3	0.64896 (19)	1.09097 (16)	0.56567 (8)	0.0797 (5)
O4	0.10989 (15)	0.42056 (11)	0.66269 (5)	0.0475 (3)
N1	0.56076 (17)	1.14379 (16)	0.61491 (7)	0.0494 (3)
N2	0.25299 (15)	0.67241 (13)	0.63378 (6)	0.0367 (3)
H2B	0.2098	0.6146	0.6665	0.044*
C7	0.27637 (17)	0.61689 (15)	0.56560 (7)	0.0353 (3)
H7A	0.3301	0.6755	0.5304	0.042*
C1	0.19513 (18)	0.87143 (15)	0.71860 (7)	0.0372 (3)
C2	0.2271 (2)	1.01473 (16)	0.74472 (8)	0.0433 (4)
H2A	0.1653	1.0508	0.7847	0.052*
C3	0.3485 (2)	1.10366 (16)	0.71228 (8)	0.0430 (4)
H3A	0.3688	1.1995	0.7297	0.052*
C4	0.44018 (19)	1.04784 (16)	0.65308 (8)	0.0383 (3)
C5	0.41405 (19)	0.90591 (15)	0.62591 (8)	0.0382 (3)
H5A	0.4778	0.8706	0.5863	0.046*
C6	0.29168 (18)	0.81772 (15)	0.65867 (7)	0.0346 (3)
C8	0.22475 (18)	0.47420 (15)	0.54298 (7)	0.0330 (3)
C9	0.13664 (18)	0.37863 (15)	0.59295 (7)	0.0357 (3)
C10	0.0795 (2)	0.23976 (16)	0.56283 (8)	0.0430 (4)
H10A	0.0199	0.1758	0.5934	0.052*
C11	0.1105 (2)	0.19794 (16)	0.48953 (9)	0.0464 (4)
H11A	0.0724	0.1056	0.4714	0.056*
C12	0.1984 (2)	0.29107 (17)	0.44103 (8)	0.0443 (4)
H12A	0.2196	0.2601	0.3915	0.053*
C13	0.25243 (19)	0.42681 (15)	0.46681 (8)	0.0380 (3)
H13A	0.3082	0.4895	0.4342	0.046*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0648 (7)	0.0424 (6)	0.0510 (6)	−0.0085 (5)	0.0346 (5)	−0.0106 (5)
O2	0.0823 (9)	0.0445 (8)	0.0842 (9)	−0.0225 (7)	0.0183 (7)	−0.0007 (6)
O3	0.0888 (10)	0.0751 (10)	0.0847 (9)	−0.0308 (8)	0.0520 (8)	−0.0116 (7)
O4	0.0642 (7)	0.0413 (6)	0.0418 (5)	−0.0029 (5)	0.0272 (5)	0.0021 (4)
N1	0.0507 (8)	0.0468 (8)	0.0520 (7)	−0.0143 (6)	0.0115 (6)	0.0001 (6)
N2	0.0446 (6)	0.0301 (6)	0.0385 (6)	−0.0019 (5)	0.0180 (5)	−0.0009 (5)
C7	0.0367 (7)	0.0335 (7)	0.0383 (7)	−0.0011 (6)	0.0153 (5)	0.0007 (5)
C1	0.0465 (8)	0.0325 (7)	0.0348 (6)	−0.0015 (6)	0.0140 (6)	0.0004 (5)
C2	0.0530 (9)	0.0387 (8)	0.0407 (7)	0.0013 (7)	0.0159 (6)	−0.0064 (6)
C3	0.0518 (9)	0.0337 (8)	0.0439 (7)	−0.0056 (6)	0.0068 (6)	−0.0033 (6)
C4	0.0412 (7)	0.0361 (8)	0.0383 (7)	−0.0059 (6)	0.0075 (6)	0.0018 (6)
C5	0.0422 (8)	0.0354 (8)	0.0390 (7)	−0.0021 (6)	0.0138 (6)	−0.0021 (6)
C6	0.0407 (7)	0.0298 (7)	0.0346 (6)	0.0003 (6)	0.0091 (5)	−0.0021 (5)
C8	0.0347 (6)	0.0303 (7)	0.0360 (6)	0.0010 (5)	0.0133 (5)	0.0007 (5)
C9	0.0378 (7)	0.0324 (7)	0.0390 (7)	0.0034 (6)	0.0138 (5)	0.0035 (5)
C10	0.0466 (8)	0.0327 (8)	0.0509 (8)	−0.0040 (6)	0.0109 (6)	0.0070 (6)
C11	0.0552 (9)	0.0316 (8)	0.0522 (8)	−0.0028 (7)	0.0050 (7)	−0.0038 (6)
C12	0.0551 (9)	0.0401 (9)	0.0390 (7)	0.0018 (7)	0.0113 (6)	−0.0043 (6)
C13	0.0434 (7)	0.0347 (8)	0.0382 (7)	0.0007 (6)	0.0156 (6)	0.0002 (5)

Geometric parameters (Å, °)

O1—C1	1.3310 (16)	C3—C4	1.3847 (19)
O1—H1O	0.8200	C3—H3A	0.9300
O2—N1	1.2170 (18)	C4—C5	1.3813 (19)
O3—N1	1.2262 (16)	C5—C6	1.3776 (19)
O4—C9	1.2997 (15)	C5—H5A	0.9300
N1—C4	1.4574 (18)	C8—C13	1.4210 (17)
N2—C7	1.3105 (16)	C8—C9	1.4325 (18)
N2—C6	1.4107 (17)	C9—C10	1.414 (2)
N2—H2B	0.8600	C10—C11	1.366 (2)
C7—C8	1.3977 (19)	C10—H10A	0.9300
C7—H7A	0.9300	C11—C12	1.402 (2)
C1—C2	1.392 (2)	C11—H11A	0.9300
C1—C6	1.4089 (18)	C12—C13	1.359 (2)
C2—C3	1.374 (2)	C12—H12A	0.9300
C2—H2A	0.9300	C13—H13A	0.9300
C1—O1—H1O	109.5	C6—C5—H5A	120.7
O2—N1—O3	122.66 (14)	C4—C5—H5A	120.7
O2—N1—C4	118.75 (13)	C5—C6—C1	120.61 (12)
O3—N1—C4	118.56 (14)	C5—C6—N2	122.80 (12)
C7—N2—C6	126.38 (12)	C1—C6—N2	116.58 (12)
C7—N2—H2B	116.8	C7—C8—C13	118.57 (12)
C6—N2—H2B	116.8	C7—C8—C9	121.65 (11)
N2—C7—C8	123.41 (12)	C13—C8—C9	119.70 (12)
N2—C7—H7A	118.3	O4—C9—C10	122.26 (12)
C8—C7—H7A	118.3	O4—C9—C8	120.42 (12)
O1—C1—C2	123.82 (12)	C10—C9—C8	117.32 (12)
O1—C1—C6	117.37 (12)	C11—C10—C9	121.09 (13)
C2—C1—C6	118.80 (12)	C11—C10—H10A	119.5
C3—C2—C1	121.01 (13)	C9—C10—H10A	119.5
C3—C2—H2A	119.5	C10—C11—C12	121.48 (14)
C1—C2—H2A	119.5	C10—C11—H11A	119.3
C2—C3—C4	118.72 (14)	C12—C11—H11A	119.3
C2—C3—H3A	120.6	C13—C12—C11	119.57 (13)
C4—C3—H3A	120.6	C13—C12—H12A	120.2
C5—C4—C3	122.21 (13)	C11—C12—H12A	120.2
C5—C4—N1	118.47 (13)	C12—C13—C8	120.82 (13)
C3—C4—N1	119.23 (13)	C12—C13—H13A	119.6
C6—C5—C4	118.64 (12)	C8—C13—H13A	119.6
C6—N2—C7—C8	−175.95 (12)	C2—C1—C6—N2	−179.38 (12)
O1—C1—C2—C3	−178.63 (14)	C7—N2—C6—C5	−22.8 (2)
C6—C1—C2—C3	0.9 (2)	C7—N2—C6—C1	155.85 (13)
C1—C2—C3—C4	−0.4 (2)	N2—C7—C8—C13	178.40 (13)
C2—C3—C4—C5	−0.3 (2)	N2—C7—C8—C9	1.8 (2)
C2—C3—C4—N1	176.22 (13)	C7—C8—C9—O4	−3.2 (2)
O2—N1—C4—C5	170.80 (13)	C13—C8—C9—O4	−179.81 (12)
O3—N1—C4—C5	−7.5 (2)	C7—C8—C9—C10	176.10 (12)
O2—N1—C4—C3	−5.8 (2)	C13—C8—C9—C10	−0.49 (19)
O3—N1—C4—C3	175.92 (14)	O4—C9—C10—C11	−179.51 (13)
C3—C4—C5—C6	0.4 (2)	C8—C9—C10—C11	1.2 (2)
N1—C4—C5—C6	−176.08 (12)	C9—C10—C11—C12	−0.6 (2)
C4—C5—C6—C1	0.1 (2)	C10—C11—C12—C13	−0.8 (2)
C4—C5—C6—N2	178.66 (12)	C11—C12—C13—C8	1.5 (2)
O1—C1—C6—C5	178.83 (12)	C7—C8—C13—C12	−177.54 (13)
C2—C1—C6—C5	−0.7 (2)	C9—C8—C13—C12	−0.8 (2)
O1—C1—C6—N2	0.15 (19)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O4i	0.82	1.72	2.5407 (13)	175
N2—H2B···O4	0.86	1.91	2.5973 (15)	135
N2—H2B···O1	0.86	2.34	2.6532 (14)	102
C2—H2A···O4i	0.93	2.60	3.2233 (18)	125
C13—H13A···O2ii	0.93	2.65	3.5555 (19)	163

Symmetry codes: (i) −x, y+1/2, −z+3/2; (ii) −x+1, −y+2, −z+1.