4-(2,4,6-Trinitro­anilino)benzoic acid

4-(2,4,6-Trinitro­anilino)benzoic acid (p-picramino­benzoic acid), C₁₃H₈N₄O₈, obtained by the reaction of 2,4,6-trinitro­benzene­sulfonic acid (picrylsulfonic acid) with 4-amino­benzoic acid in 2-propanol–water, forms a two-dimensional hydrogen-bonded network based on centrosymmetric cyclic R²₂(8) carboxylic acid dimers which are extended through lateral N—H...O_carbox­yl inter­actions. The amino group also makes an intra­molecular N—H...O_nitro hydrogen bond, while the two aromatic ring systems, are, as expected, non-coplanar, the C—C—N—C torsion angles being 152.0 (2) (picryl) and 136.1 (2)° (benzoic acid)..

Key indicators

• Single-crystal X-ray study
• T = 130 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.044
• wR factor = 0.100
• Data-to-parameter ratio = 10.5

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT432_ALERT_2_B Short Inter X...Y Contact  O62    ..  C1      ..       2.91 Ang.

Alert level C
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.43 Ratio
PLAT432_ALERT_2_C Short Inter X...Y Contact  O62    ..  C2      ..       2.97 Ang.

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Picryl chloride (1-chloro-2,4,6-trinitrobenzene) reacts with the isomeric aminobenzoic acids to give the corresponding picraminobenzoic acids (Crocker & Matthews, 1911). The same reaction products may be obtained using picrylsulfonic acid (2,4,6-trinitrobenzenesulfonic acid) and the metal salts of these three compounds have been investigated for their potential as energetic ballistic modifiers (Palaiah et al., 2000; Nair et al., 2001; Kulkarni et al., 2005). Similar addition compounds are obtained with amino acids and proteins (Goldfarb, 1966) while we have also found that picrylsulfonic acid reacts with guanidine carbonate in methanol to give the analogous picrylguanidine (Smith et al., 2007a). This is in contrast to the formation of the proton-transfer salt guanidinium picrylsulfonate (Russell & Ward, 1997) from the reaction of picrylsulfonic acid with guanidinium chloride in methanol-toluene solution. The structures of the salt quinolinium picrylsulfonate (Smith et al., 2006) and the adduct salt 2-carboxyquinolinium-picrylsulfonate-quinolinium-2-carboxylate (1/1/1) (Smith et al., 2007b) are also known. Of the three isomeric picraminobenzoic acids synthesized from picrylsulfonic acid, only the para-isomer 4-(2,4,6-trinitroanilino)benzoic acid (I) proved suitable for X-ray analysis and the structure is reported here.

The molecules of the title compound (Fig. 1) form centrosymmetric hydrogen-bonded cyclic homodimers [graph set R²₂(8)] which are extended into a two-dimensional network structure through lateral N—H···O_carboxyl interactions (Fig. 2; Table 1). The amino-N forms an intramolecular hydrogen bond with an O-acceptor of one of the ortho- related nitro groups which is less rotated out of the plane of the benzene ring than the second, more sterically encumbered group [torsion angle C1–C2–N2–O22, -155.43 (19) ° cf. C5–C6–N6–O62, 123.1 (2) °]. The third group is essentially coplanar with the ring [C3–C4–N4–O42, 177.4 (2) °]. The carboxylic acid group also lies out of the plane of the benzene ring [torsion angle C21–C11–C71–O721, -165.4 (2) °] while this ring is also rotated out of the plane of the picryl residue [torsion angles C2–C1–N14–C41, 152.0 (2) Å; C1–N14–C41–C51, 136.1 (2) Å].

Related literature

For the structures of related picryl-substituted compounds: see Russell & Ward (1997); Smith et al. (2006, 2007a). For the synthesis of picraminobenzoic acids and their salts, see: Crocker & Matthews (1911). For related literature, see: Goldfarb (1966); Kulkarni et al. (2005); Nair et al. (2001); Palaiah et al. (2000); Smith et al. (2007b).

S2. Experimental

The title compound was synthesized by heating under reflux 1 mmol quantities of 2,4,6-trinitrobenzenesulfonic acid (picrylsulfonic acid) and 4-aminobenzoic acid in 50 ml of 80% propan-2-ol-water for 10 minutes. This reaction is analogous to that of picryl chloride with 4-amimobenzoic acid (Crocker & Matthews, 1911) which gives the same product. After concentration to ca 30 ml, partial room temperature evaporation of the hot-filtered solution gave yellow prisms of (I) [m.pt. 558 K (Crocker & Matthews, 1911)].

S3. Refinement

Interactive hydrogen atoms were located by difference methods and their positional and isotropic displacement parameters were refined. The aromatic ring H atoms were included in the refinement in calculated positions (C–H = 0.95 Å) using a riding model approximation, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART (Bruker, 2000); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. Molecular configuration and atom naming scheme for (I). Non-H atom displacement ellipsoids are drawn at the 40% probability level.
	Fig. 2. A perspective view of the two-dimensional network structure of (I) showing the cyclic R^22(8) centrosymmetric hydrogen-bonded carboxylic acid homodimers extended through N–H···Ocarboxyl associations. Hydrogen bonds are shown as dashed lines. Symmetry code (iv): 1 - x, 1/2 + y, 3/2 - z. For other symmetry codes, see Table 1.

4-(2,4,6-Trinitroanilino)benzoic acid

Crystal data

C13H8N4O8	F(000) = 712
Mr = 348.23	Dx = 1.646 Mg m^−3
Monoclinic, P21/c	Melting point: 558 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 20.317 (2) Å	Cell parameters from 1942 reflections
b = 5.0919 (5) Å	θ = 3.0–27.4°
c = 13.9364 (15) Å	µ = 0.14 mm^−1
β = 102.903 (2)°	T = 130 K
V = 1405.4 (2) Å^3	Needle, yellow
Z = 4	0.45 × 0.06 × 0.06 mm

Data collection

Bruker CCD area-detector diffractometer	2462 independent reflections
Radiation source: sealed tube	2057 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ϕ and ω scans	θmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −24→22
Tmin = 0.95, Tmax = 0.99	k = −5→6
5876 measured reflections	l = −6→16

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.100	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0309P)^2 + 0.4928P] where P = (Fo^2 + 2Fc^2)/3
2462 reflections	(Δ/σ)max < 0.001
234 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.21 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
O21	0.28495 (8)	0.6642 (3)	0.35981 (12)	0.0277 (5)
O22	0.19826 (8)	0.9192 (3)	0.31493 (11)	0.0256 (5)
O41	−0.02274 (8)	0.5879 (4)	0.29940 (13)	0.0373 (6)
O42	−0.03744 (8)	0.2949 (3)	0.40479 (13)	0.0342 (6)
O61	0.16455 (8)	0.0561 (3)	0.66743 (11)	0.0315 (6)
O62	0.22289 (8)	−0.1459 (3)	0.57694 (12)	0.0280 (5)
O711	0.42517 (8)	0.1190 (4)	0.95005 (11)	0.0337 (6)
O721	0.49608 (8)	−0.0810 (4)	0.87222 (13)	0.0362 (6)
N2	0.22466 (9)	0.7173 (4)	0.35345 (13)	0.0203 (6)
N4	−0.00133 (9)	0.4347 (4)	0.36657 (14)	0.0251 (6)
N6	0.18611 (9)	0.0327 (4)	0.59289 (13)	0.0210 (6)
N14	0.28062 (9)	0.3181 (4)	0.49909 (13)	0.0199 (6)
C1	0.21318 (11)	0.3574 (4)	0.47150 (15)	0.0171 (6)
C2	0.18317 (10)	0.5347 (4)	0.39510 (15)	0.0175 (6)
C3	0.11423 (11)	0.5621 (4)	0.36082 (15)	0.0192 (7)
C4	0.07171 (11)	0.4169 (4)	0.40398 (16)	0.0205 (7)
C5	0.09676 (11)	0.2531 (4)	0.48320 (16)	0.0202 (7)
C6	0.16532 (11)	0.2273 (4)	0.51474 (15)	0.0179 (6)
C11	0.39836 (10)	0.1101 (4)	0.77544 (16)	0.0199 (7)
C21	0.34772 (11)	0.2976 (4)	0.76841 (16)	0.0208 (7)
C31	0.30798 (11)	0.3645 (4)	0.67791 (15)	0.0198 (7)
C41	0.31861 (10)	0.2401 (4)	0.59402 (15)	0.0183 (7)
C51	0.36815 (10)	0.0491 (4)	0.60025 (16)	0.0207 (7)
C61	0.40803 (11)	−0.0152 (5)	0.69090 (16)	0.0226 (7)
C71	0.44058 (11)	0.0511 (5)	0.87385 (16)	0.0240 (7)
H3	0.09660	0.67930	0.30830	0.0230*
H5	0.06700	0.16060	0.51490	0.0240*
H14	0.3038 (12)	0.386 (5)	0.4598 (17)	0.026 (7)*
H21	0.34040	0.38020	0.82630	0.0250*
H31	0.27370	0.49410	0.67310	0.0240*
H51	0.37450	−0.03660	0.54250	0.0250*
H61	0.44210	−0.14510	0.69560	0.0270*
H721	0.5209 (17)	−0.101 (7)	0.934 (3)	0.079 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O21	0.0207 (8)	0.0318 (10)	0.0317 (9)	0.0033 (7)	0.0083 (7)	0.0084 (8)
O22	0.0308 (9)	0.0194 (9)	0.0260 (9)	0.0026 (7)	0.0048 (7)	0.0061 (7)
O41	0.0263 (9)	0.0420 (11)	0.0392 (11)	0.0068 (8)	−0.0023 (8)	0.0146 (9)
O42	0.0219 (9)	0.0400 (11)	0.0414 (11)	−0.0048 (8)	0.0084 (8)	0.0058 (9)
O61	0.0345 (10)	0.0403 (11)	0.0203 (9)	−0.0016 (8)	0.0073 (7)	0.0072 (8)
O62	0.0305 (9)	0.0183 (9)	0.0310 (9)	0.0035 (7)	−0.0021 (8)	0.0005 (7)
O711	0.0282 (9)	0.0546 (12)	0.0168 (9)	0.0165 (9)	0.0017 (7)	−0.0008 (8)
O721	0.0270 (10)	0.0586 (13)	0.0202 (9)	0.0228 (9)	−0.0009 (8)	0.0017 (9)
N2	0.0235 (10)	0.0198 (11)	0.0167 (9)	−0.0014 (8)	0.0027 (8)	−0.0010 (8)
N4	0.0213 (10)	0.0267 (12)	0.0266 (11)	0.0017 (9)	0.0037 (9)	−0.0011 (9)
N6	0.0215 (10)	0.0187 (11)	0.0199 (10)	−0.0031 (8)	−0.0017 (8)	0.0025 (8)
N14	0.0177 (10)	0.0243 (11)	0.0169 (10)	0.0021 (8)	0.0022 (8)	0.0029 (8)
C1	0.0218 (11)	0.0144 (11)	0.0149 (11)	0.0019 (9)	0.0035 (9)	−0.0047 (9)
C2	0.0221 (11)	0.0161 (12)	0.0148 (10)	0.0002 (9)	0.0049 (9)	−0.0015 (9)
C3	0.0219 (11)	0.0198 (13)	0.0144 (11)	0.0032 (10)	0.0008 (9)	−0.0004 (9)
C4	0.0182 (11)	0.0232 (13)	0.0187 (11)	0.0008 (10)	0.0011 (9)	−0.0016 (10)
C5	0.0224 (12)	0.0191 (12)	0.0194 (11)	−0.0018 (10)	0.0053 (9)	−0.0020 (9)
C6	0.0221 (11)	0.0155 (12)	0.0145 (10)	0.0021 (9)	0.0006 (9)	0.0009 (9)
C11	0.0161 (11)	0.0228 (13)	0.0198 (11)	0.0012 (9)	0.0018 (9)	0.0041 (10)
C21	0.0218 (12)	0.0202 (12)	0.0188 (11)	−0.0002 (10)	0.0011 (9)	−0.0007 (9)
C31	0.0177 (11)	0.0180 (12)	0.0218 (12)	0.0052 (9)	0.0007 (9)	0.0013 (10)
C41	0.0162 (11)	0.0198 (12)	0.0174 (11)	−0.0017 (9)	0.0007 (9)	0.0030 (9)
C51	0.0209 (11)	0.0235 (13)	0.0177 (11)	0.0008 (10)	0.0043 (9)	−0.0005 (9)
C61	0.0172 (11)	0.0239 (13)	0.0260 (12)	0.0049 (10)	0.0033 (9)	0.0028 (10)
C71	0.0190 (11)	0.0300 (14)	0.0217 (12)	0.0048 (10)	0.0019 (10)	0.0045 (10)

Geometric parameters (Å, º)

O21—N2	1.238 (3)	C2—C3	1.382 (3)
O22—N2	1.227 (3)	C3—C4	1.374 (3)
O41—N4	1.222 (3)	C4—C5	1.387 (3)
O42—N4	1.226 (3)	C5—C6	1.370 (3)
O61—N6	1.220 (2)	C11—C71	1.477 (3)
O62—N6	1.228 (3)	C11—C21	1.391 (3)
O711—C71	1.222 (3)	C11—C61	1.392 (3)
O721—C71	1.318 (3)	C21—C31	1.380 (3)
O721—H721	0.90 (4)	C31—C41	1.388 (3)
N2—C2	1.460 (3)	C41—C51	1.388 (3)
N4—C4	1.462 (3)	C51—C61	1.379 (3)
N6—C6	1.463 (3)	C3—H3	0.9500
N14—C41	1.431 (3)	C5—H5	0.9500
N14—C1	1.353 (3)	C21—H21	0.9500
N14—H14	0.87 (2)	C31—H31	0.9500
C1—C6	1.418 (3)	C51—H51	0.9500
C1—C2	1.425 (3)	C61—H61	0.9500
C71—O721—H721	110 (2)	N6—C6—C5	114.05 (19)
O21—N2—C2	118.84 (18)	C61—C11—C71	122.0 (2)
O22—N2—C2	118.23 (18)	C21—C11—C71	118.2 (2)
O21—N2—O22	122.91 (19)	C21—C11—C61	119.8 (2)
O41—N4—C4	118.19 (18)	C11—C21—C31	120.4 (2)
O42—N4—C4	117.86 (18)	C21—C31—C41	119.2 (2)
O41—N4—O42	123.95 (19)	N14—C41—C31	119.91 (19)
O61—N6—C6	117.96 (18)	N14—C41—C51	119.08 (19)
O62—N6—C6	116.92 (17)	C31—C41—C51	120.92 (19)
O61—N6—O62	125.10 (19)	C41—C51—C61	119.5 (2)
C1—N14—C41	127.36 (18)	C11—C61—C51	120.1 (2)
C41—N14—H14	115.9 (16)	O711—C71—O721	123.1 (2)
C1—N14—H14	114.8 (16)	O711—C71—C11	122.8 (2)
N14—C1—C6	123.88 (19)	O721—C71—C11	114.18 (19)
N14—C1—C2	122.9 (2)	C2—C3—H3	121.00
C2—C1—C6	113.21 (19)	C4—C3—H3	121.00
N2—C2—C1	120.80 (18)	C4—C5—H5	121.00
N2—C2—C3	115.40 (18)	C6—C5—H5	121.00
C1—C2—C3	123.62 (19)	C11—C21—H21	120.00
C2—C3—C4	118.83 (19)	C31—C21—H21	120.00
N4—C4—C5	119.0 (2)	C21—C31—H31	120.00
N4—C4—C3	119.87 (19)	C41—C31—H31	120.00
C3—C4—C5	121.2 (2)	C41—C51—H51	120.00
C4—C5—C6	118.6 (2)	C61—C51—H51	120.00
N6—C6—C1	121.43 (19)	C11—C61—H61	120.00
C1—C6—C5	124.30 (19)	C51—C61—H61	120.00
O21—N2—C2—C1	23.5 (3)	N14—C1—C6—N6	−1.3 (3)
O22—N2—C2—C1	−155.43 (19)	C1—C2—C3—C4	1.9 (3)
O21—N2—C2—C3	−161.37 (19)	N2—C2—C3—C4	−173.13 (19)
O22—N2—C2—C3	19.7 (3)	C2—C3—C4—C5	2.6 (3)
O41—N4—C4—C3	−2.7 (3)	C2—C3—C4—N4	−177.63 (19)
O42—N4—C4—C3	177.4 (2)	C3—C4—C5—C6	−3.5 (3)
O41—N4—C4—C5	177.0 (2)	N4—C4—C5—C6	176.78 (19)
O42—N4—C4—C5	−2.8 (3)	C4—C5—C6—N6	−174.90 (19)
O62—N6—C6—C1	−51.9 (3)	C4—C5—C6—C1	−0.1 (3)
O62—N6—C6—C5	123.1 (2)	C61—C11—C21—C31	−1.5 (3)
O61—N6—C6—C5	−55.2 (3)	C71—C11—C61—C51	−178.9 (2)
O61—N6—C6—C1	129.8 (2)	C71—C11—C21—C31	178.4 (2)
C41—N14—C1—C2	152.0 (2)	C21—C11—C61—C51	0.9 (3)
C1—N14—C41—C51	136.1 (2)	C61—C11—C71—O711	−165.5 (2)
C1—N14—C41—C31	−47.1 (3)	C61—C11—C71—O721	14.4 (3)
C41—N14—C1—C6	−28.2 (3)	C21—C11—C71—O711	14.7 (3)
N14—C1—C2—N2	−10.5 (3)	C21—C11—C71—O721	−165.4 (2)
C2—C1—C6—N6	178.50 (18)	C11—C21—C31—C41	0.8 (3)
C2—C1—C6—C5	4.1 (3)	C21—C31—C41—C51	0.5 (3)
N14—C1—C6—C5	−175.7 (2)	C21—C31—C41—N14	−176.3 (2)
C6—C1—C2—N2	169.77 (18)	N14—C41—C51—C61	175.8 (2)
N14—C1—C2—C3	174.8 (2)	C31—C41—C51—C61	−1.0 (3)
C6—C1—C2—C3	−5.0 (3)	C41—C51—C61—C11	0.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N14—H14···O21	0.87 (2)	1.96 (2)	2.638 (2)	133 (2)
N14—H14···O711^i	0.87 (2)	2.50 (3)	3.177 (3)	135 (2)
O721—H721···O711^ii	0.90 (4)	1.74 (4)	2.639 (2)	174 (3)
C31—H31···O62^iii	0.95	2.37	3.178 (3)	143

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