2-Amino-5-nitro-benzoic acid.

In the title compound, C(7)H(6)N(2)O(4), an intra-molecular N-H⋯O hydrogen bond generates an S(6) ring. In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R(2) (2)(8) loops. Inter-molecular N-H⋯O and C-H⋯O hydrogen bonds then link the dimers, generating R(3) (3)(16)R(2) (1)(6) motifs. The whole mol-ecule is essentially planar, with the greatest deviation from the mean plane being 0.065 (2) Å.

Related literature

For related structures of carb­oxy­lic acides, see: Mrozek & Glowiak (2004 ▶); Raza et al. (2010 ▶); Grabowski & Krygowski (1985 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For general background to o-amino­carb­oxy­lic acids, see: Fierz et al. (1949 ▶); Shore (2002 ▶).

Experimental

Crystal data

C7H6N2O4

M = 182.14

Monoclinic,

a = 3.7026 (3) Å

b = 17.4638 (16) Å

c = 11.6953 (10) Å

β = 92.210 (7)°

V = 755.67 (11) Å3

Z = 4

Mo Kα radiation

μ = 0.13 mm−1

T = 296 K

0.55 × 0.23 × 0.06 mm

Data collection

Stoe IPDS II diffractometer

Absorption correction: integration (X-RED32; Stoe & Cie, 2002 ▶) T min = 0.964, T max = 0.992

5176 measured reflections

1567 independent reflections

884 reflections with I > 2σ(I)

R int = 0.077

Refinement

R[F 2 > 2σ(F 2)] = 0.064

wR(F 2) = 0.127

S = 0.99

1567 reflections

118 parameters

H-atom parameters constrained

Δρmax = 0.18 e Å−3

Δρmin = −0.15 e Å−3

Data collection: X-AREA (Stoe & Cie, 2002 ▶); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812002474/fk2050sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812002474/fk2050Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536812002474/fk2050Isup3.cml

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

C7H6N2O4	F(000) = 376
Mr = 182.14	Dx = 1.601 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4323 reflections
a = 3.7026 (3) Å	θ = 1.7–28.0°
b = 17.4638 (16) Å	µ = 0.13 mm−1
c = 11.6953 (10) Å	T = 296 K
β = 92.210 (7)°	Needle, orange
V = 755.67 (11) Å3	0.55 × 0.23 × 0.06 mm
Z = 4

Stoe IPDS II diffractometer	1567 independent reflections
Radiation source: fine-focus sealed tube	884 reflections with I > 2σ(I)
graphite	Rint = 0.077
Detector resolution: 6.67 pixels mm-1	θmax = 26.5°, θmin = 2.1°
rotation method scans	h = −4→4
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −21→21
Tmin = 0.964, Tmax = 0.992	l = −13→14
5176 measured reflections

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)] = 0.064	Hydrogen site location: geom and difmap
wR(F2) = 0.127	H-atom parameters constrained
S = 0.99	w = 1/[σ2(Fo2) + (0.0486P)2] where P = (Fo2 + 2Fc2)/3
1567 reflections	(Δ/σ)max < 0.001
118 parameters	Δρmax = 0.18 e Å−3
0 restraints	Δρmin = −0.15 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.

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.

	x	y	z	Uiso*/Ueq
C1	0.6059 (8)	0.35123 (17)	0.7289 (3)	0.0393 (7)
C2	0.7771 (8)	0.34418 (16)	0.8394 (2)	0.0346 (7)
C3	0.8661 (8)	0.27231 (16)	0.8809 (3)	0.0370 (7)
H3	0.9810	0.2678	0.9527	0.044*
C4	0.7890 (8)	0.20744 (16)	0.8187 (3)	0.0380 (7)
C5	0.6210 (9)	0.21311 (18)	0.7098 (3)	0.0444 (8)
H5	0.5688	0.1692	0.6673	0.053*
C6	0.5351 (9)	0.28294 (17)	0.6667 (3)	0.0431 (8)
H6	0.4261	0.2862	0.5939	0.052*
C7	0.8660 (8)	0.41190 (17)	0.9097 (2)	0.0383 (7)
N1	0.5107 (8)	0.41812 (15)	0.6824 (2)	0.0548 (8)
H8	0.4074	0.4196	0.6154	0.066*
H7	0.5526	0.4599	0.7195	0.066*
N2	0.8912 (8)	0.13354 (14)	0.8636 (2)	0.0502 (7)
O1	0.7787 (6)	0.47709 (12)	0.88101 (17)	0.0513 (6)
O2	1.0433 (6)	0.39701 (12)	1.00684 (18)	0.0528 (7)
H2	1.0837	0.4371	1.0415	0.079*
O3	1.0514 (7)	0.12980 (13)	0.9571 (2)	0.0681 (8)
O4	0.8171 (9)	0.07683 (14)	0.8068 (2)	0.0845 (10)

	U11	U22	U33	U12	U13	U23
C1	0.0370 (18)	0.0391 (17)	0.0415 (17)	0.0007 (14)	−0.0015 (13)	0.0015 (13)
C2	0.0378 (17)	0.0336 (16)	0.0325 (15)	−0.0016 (14)	−0.0002 (12)	−0.0043 (13)
C3	0.0391 (18)	0.0395 (16)	0.0321 (16)	−0.0021 (14)	−0.0016 (13)	−0.0019 (12)
C4	0.0395 (18)	0.0330 (16)	0.0416 (18)	−0.0020 (13)	0.0014 (13)	−0.0032 (13)
C5	0.048 (2)	0.0421 (19)	0.0429 (18)	−0.0067 (15)	−0.0033 (14)	−0.0124 (14)
C6	0.0469 (19)	0.047 (2)	0.0346 (17)	−0.0021 (15)	−0.0062 (14)	−0.0048 (13)
C7	0.0434 (19)	0.0348 (18)	0.0365 (16)	−0.0006 (14)	−0.0019 (14)	−0.0014 (13)
N1	0.080 (2)	0.0407 (15)	0.0426 (15)	0.0062 (15)	−0.0147 (14)	0.0012 (12)
N2	0.0641 (19)	0.0336 (15)	0.0525 (17)	−0.0013 (14)	−0.0031 (14)	−0.0037 (13)
O1	0.0766 (17)	0.0322 (12)	0.0440 (12)	−0.0002 (11)	−0.0120 (11)	−0.0020 (10)
O2	0.0786 (17)	0.0343 (11)	0.0440 (13)	−0.0030 (11)	−0.0187 (12)	−0.0061 (9)
O3	0.101 (2)	0.0436 (14)	0.0573 (15)	0.0040 (13)	−0.0228 (15)	0.0032 (11)
O4	0.134 (3)	0.0334 (14)	0.084 (2)	−0.0019 (15)	−0.0263 (18)	−0.0118 (13)

C1—N1	1.330 (4)	C5—H5	0.9300
C1—C6	1.416 (4)	C6—H6	0.9300
C1—C2	1.423 (4)	C7—O1	1.227 (3)
C2—C3	1.381 (4)	C7—O2	1.316 (3)
C2—C7	1.470 (4)	N1—H8	0.8600
C3—C4	1.370 (4)	N1—H7	0.8600
C3—H3	0.9300	N2—O4	1.218 (3)
C4—C5	1.399 (4)	N2—O3	1.226 (3)
C4—N2	1.439 (4)	O2—H2	0.8200
C5—C6	1.353 (4)
N1—C1—C6	119.3 (3)	C4—C5—H5	120.2
N1—C1—C2	123.3 (3)	C5—C6—C1	122.1 (3)
C6—C1—C2	117.4 (3)	C5—C6—H6	118.9
C3—C2—C1	119.3 (3)	C1—C6—H6	118.9
C3—C2—C7	119.3 (3)	O1—C7—O2	122.5 (3)
C1—C2—C7	121.4 (3)	O1—C7—C2	122.9 (3)
C4—C3—C2	121.5 (3)	O2—C7—C2	114.7 (3)
C4—C3—H3	119.2	C1—N1—H8	120.0
C2—C3—H3	119.2	C1—N1—H7	120.0
C3—C4—C5	120.1 (3)	H8—N1—H7	120.0
C3—C4—N2	120.1 (3)	O4—N2—O3	122.3 (3)
C5—C4—N2	119.8 (3)	O4—N2—C4	118.7 (3)
C6—C5—C4	119.5 (3)	O3—N2—C4	119.0 (3)
C6—C5—H5	120.2	C7—O2—H2	109.5
N1—C1—C2—C3	179.9 (3)	N1—C1—C6—C5	−179.1 (3)
C6—C1—C2—C3	0.1 (4)	C2—C1—C6—C5	0.8 (4)
N1—C1—C2—C7	−1.0 (4)	C3—C2—C7—O1	−176.2 (3)
C6—C1—C2—C7	179.1 (3)	C1—C2—C7—O1	4.8 (5)
C1—C2—C3—C4	−0.9 (4)	C3—C2—C7—O2	3.1 (4)
C7—C2—C3—C4	180.0 (3)	C1—C2—C7—O2	−176.0 (3)
C2—C3—C4—C5	1.0 (5)	C3—C4—N2—O4	179.5 (3)
C2—C3—C4—N2	178.9 (3)	C5—C4—N2—O4	−2.5 (5)
C3—C4—C5—C6	−0.1 (5)	C3—C4—N2—O3	−0.9 (5)
N2—C4—C5—C6	−178.1 (3)	C5—C4—N2—O3	177.0 (3)
C4—C5—C6—C1	−0.7 (5)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H7···O1	0.86	2.06	2.694 (3)	130
N1—H7···O4i	0.86	2.47	3.030 (3)	123
N1—H8···O3ii	0.86	2.39	3.192 (4)	155
O2—H2···O1iii	0.82	1.81	2.631 (3)	174
C6—H6···O3ii	0.93	2.54	3.347 (4)	145 (3)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H7⋯O1	0.86	2.06	2.694 (3)	130
N1—H7⋯O4i	0.86	2.47	3.030 (3)	123
N1—H8⋯O3ii	0.86	2.39	3.192 (4)	155
O2—H2⋯O1iii	0.82	1.81	2.631 (3)	174
C6—H6⋯O3ii	0.93	2.54	3.347 (4)	145 (3)

Symmetry codes: (i) ; (ii) ; (iii) .