2-Hydro­xy-5-[(E)-(4-methoxy­phenyl)­diazenyl]­benzoic acid

The title compound, C₁₄H₁₂N₂O₄, shows an E conformation about the diazenyl N atoms. The crystal structure features layers of mol­ecules with the primary connection between the layers afforded by carboxyl­ic acid dimer motifs; no evidence for extensive [pi]-[pi] stacking between the layers was found.

S1. Comment

Organotin compounds containing carboxylate ligands similar to that derived from the title compound have received considerable attention recently (Basu Baul & Tiekink, 1998, 1999; Willem et al., 1998). These systems have provided a large number of X-ray-quality crystals enabling systematic analyses and hence conclusions to be drawn as to the reasons why different motifs (Tiekink, 1991, 1994) are found for triorganotin carboxylates (Willem et al., 1998). A key feature of some of these structures is the presence of π–π interactions that serve to stabilize the crystal structure. Surprisingly, relatively little is known about the structural chemistry of diazocarboxylic acid derivatives themselves (Moreiras et al., 1980; van der Sluis & Spek, 1990) and in order to ascertain the reasons why base stacking is observed in some organotin derivatives but not in others, the structure of the title compound, (I) (Fig. 1), was investigated.

The conformation about the diazo group is E and derived interatomic parameters are as expected. The molecule is basically planar although there is a slight twist about the diazo group, as seen in the N1—N2—C8—C9 and N2—N1—C6—C5 torsion angles of 176.4 (2) and 8.5 (3)°, respectively. The dihedral angle between the two aromatic rings is 5.43 (7)°. The carboxylic acid group is coplanar with the C2–C7 ring [O1—C1—C2—C3 is −178.2 (2)°], which facilitates the formation of an intramolecular hydrogen-bonding contacts such that O3···O2 is 2.630 (2) Å (see Table 2). Intermolecular hydrogen-bonding interactions are also present.

The structure may be described as a hydrogen-bonded array in the ac plane that is stacked along b; however, the layers are not flat, there being significant corrugation within them. The arrangement of molecules within the layer is best described as being based on the coronene motif (Desiraju & Gavezzotti, 1989). The layers are stabilized in part by weak hydrogen-bonding interactions between the hydroxyl-H atom and a symmetry-related methoxy-O atom, such that O3···O4ⁱ is 3.003 (2) Å [symmetry code: (i) 1/2 + x, y, 1/2 − z]. Contacts of 3.522 (2) Å that occur between translationally related C1 and C5ⁱⁱ atoms throughout the layer are also noted [symmetry code: (ii) x, y, 1 + z]. Connections between the layers are afforded by carboxylic acid dimer formation: O1···O2ⁱⁱⁱ 2.631 (2) Å [symmetry code: (iii) 2 − x, −y, 2 − z]. No evidence was found for extensive π···π interactions in the lattice. However, between layers, centrosymmetrically related pairs of benzoic acid fragments approach each other at distances indicative of π···π interactions. The closest contact of 3.295 (2) Å occurs between C1 and C3^iv, and the average separation between the least-squares planes through each of the O₂CC₆ fragments is 3.24 Å [symmetry code: (iv) 2 − x, −y, 1 − z]. Presumably, π···π interactions involving the methoxyphenyl fragment and hence, the whole molecule, are precluded by the bulky nature of the methyl group. Finally, evidence for a C—H···ring interaction between the layers is also noted, such that the C5—H4···Cp^v (where Cp is the centroid of the C2–C7 ring) is 2.78 Å and the angle at H4 is 139° [symmetry code: (v) x, 1/2 − y, 1/2 + z].

S2. Experimental

Diazo-coupling of p-methoxyaniline and o-hydroxybenzoic acid in alkaline solution yielded the title compound in 52% yield. Recrystallization from -benzene solution gave orange-red crystals (m.p. 482–483 K).

S3. Refinement

All H atoms were located from a difference map and refined but were fixed in the final cycles of refinement (O—H 0.86 and 0.90 Å; C—H 0.95–1.03 Å).

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1999); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1997-1999); program(s) used to solve structure: SIR97 (Altomare et al., 1997); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures

Fig. 1. The molecular structure and crystallographic numbering scheme for (I). Displacement ellipsoids shown at the 50% probability level (ORTEPII; Johnson, 1976).

(I)

Crystal data

C14H12N2O4	F(000) = 1136
Mr = 272.26	Dx = 1.440 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 25 reflections
a = 24.902 (6) Å	θ = 6.4–9.6°
b = 15.109 (6) Å	µ = 0.11 mm^−1
c = 6.674 (2) Å	T = 173 K
V = 2511 (1) Å^3	Trigonal plate, orange–red
Z = 8	0.45 × 0.24 × 0.19 mm

Data collection

Rigaku AFC-7R diffractometer	Rint = 0.030
Radiation source: X-ray tube	θmax = 27.5°, θmin = 3.1°
Graphite monochromator	h = 0→32
ω scans	k = −1→19
6617 measured reflections	l = −8→8
2894 independent reflections	3 standard reflections every 400 reflections
1800 reflections with I > 2σ(I)	intensity decay: −1.4%

Refinement

Refinement on F	0 restraints
Least-squares matrix: full	0 constraints
R[F^2 > 2σ(F^2)] = 0.034	H-atom parameters not refined
wR(F^2) = 0.033	Weighting scheme based on measured s.u.'s w = 1/[σ^2(Fo) + 0.00001|Fo|^2]
S = 1.65	(Δ/σ)max < 0.0001
1800 reflections	Δρmax = 0.24 e Å^−3
181 parameters	Δρmin = −0.20 e Å^−3

Special details

Refinement. All H atoms were located from a difference map and refined (x, y, z and U_iso_) but were fixed in the final cycles of refinement.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.94177 (4)	0.01763 (7)	0.8390 (2)	0.0300 (3)
O2	1.02771 (4)	0.06121 (7)	0.8285 (1)	0.0288 (3)
O3	1.06264 (4)	0.14755 (7)	0.5120 (2)	0.0295 (3)
O4	0.64850 (4)	0.11987 (8)	−0.3216 (2)	0.0377 (3)
N1	0.85392 (5)	0.11762 (8)	0.2170 (2)	0.0297 (4)
N2	0.84935 (5)	0.14252 (8)	0.0377 (2)	0.0297 (4)
C1	0.98228 (6)	0.0576 (1)	0.7523 (2)	0.0248 (4)
C2	0.97032 (6)	0.09777 (9)	0.5580 (2)	0.0227 (4)
C3	1.01099 (6)	0.14092 (9)	0.4502 (2)	0.0229 (4)
C4	0.99862 (6)	0.18081 (9)	0.2668 (2)	0.0269 (4)
C5	0.94770 (6)	0.17542 (9)	0.1891 (2)	0.0263 (4)
C6	0.90729 (6)	0.1298 (1)	0.2921 (2)	0.0254 (4)
C7	0.91851 (6)	0.0933 (1)	0.4770 (2)	0.0248 (4)
C8	0.79720 (6)	0.1321 (1)	−0.0465 (2)	0.0275 (4)
C9	0.79165 (6)	0.1644 (1)	−0.2393 (2)	0.0310 (4)
C10	0.74264 (6)	0.1619 (1)	−0.3383 (2)	0.0314 (4)
C11	0.69877 (6)	0.1253 (1)	−0.2405 (2)	0.0278 (4)
C12	0.70427 (6)	0.0913 (1)	−0.0478 (3)	0.0336 (5)
C13	0.75293 (6)	0.0941 (1)	0.0491 (2)	0.0326 (4)
C14	0.64184 (7)	0.1524 (1)	−0.5209 (3)	0.0506 (6)
H1	0.9516	−0.0074	0.9556	0.053*
H2	1.0645	0.1236	0.6288	0.057*
H3	1.0262	0.2132	0.1986	0.031*
H4	0.9402	0.2035	0.0642	0.022*
H5	0.8911	0.0637	0.5487	0.027*
H6	0.8219	0.1928	−0.3032	0.046*
H7	0.7397	0.1858	−0.4756	0.037*
H8	0.6744	0.0626	0.0150	0.051*
H9	0.7577	0.0695	0.1844	0.040*
H10	0.6643	0.1185	−0.6154	0.092*
H11	0.6502	0.2193	−0.5258	0.071*
H12	0.6056	0.1444	−0.5521	0.051*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0274 (6)	0.0382 (6)	0.0244 (6)	−0.0033 (5)	−0.0005 (5)	0.0082 (5)
O2	0.0253 (6)	0.0378 (6)	0.0232 (5)	−0.0029 (5)	−0.0038 (5)	0.0042 (5)
O3	0.0224 (5)	0.0387 (7)	0.0275 (6)	−0.0022 (5)	−0.0023 (5)	0.0052 (5)
O4	0.0250 (6)	0.0536 (7)	0.0345 (7)	−0.0067 (6)	−0.0060 (5)	0.0073 (6)
N1	0.0266 (7)	0.0316 (7)	0.0310 (8)	0.0005 (6)	−0.0054 (6)	0.0029 (6)
N2	0.0250 (7)	0.0346 (8)	0.0294 (7)	0.0014 (6)	−0.0035 (6)	0.0017 (6)
C1	0.0271 (8)	0.0239 (8)	0.0233 (8)	0.0011 (6)	0.0014 (7)	−0.0036 (7)
C2	0.0248 (8)	0.0221 (7)	0.0211 (7)	0.0027 (6)	0.0007 (6)	−0.0011 (6)
C3	0.0212 (7)	0.0233 (8)	0.0242 (8)	0.0014 (6)	−0.0001 (6)	−0.0034 (7)
C4	0.0271 (8)	0.0267 (8)	0.0269 (8)	−0.0016 (6)	0.0022 (7)	0.0029 (7)
C5	0.0288 (8)	0.0261 (8)	0.0238 (8)	0.0016 (6)	−0.0016 (7)	0.0036 (7)
C6	0.0229 (8)	0.0270 (8)	0.0262 (8)	0.0018 (6)	−0.0025 (6)	−0.0018 (7)
C7	0.0238 (8)	0.0237 (8)	0.0270 (8)	−0.0015 (6)	0.0019 (7)	0.0001 (7)
C8	0.0234 (8)	0.0306 (9)	0.0283 (8)	0.0010 (7)	−0.0038 (7)	−0.0007 (7)
C9	0.0236 (8)	0.040 (1)	0.0290 (9)	−0.0031 (7)	0.0011 (7)	0.0037 (8)
C10	0.0296 (8)	0.039 (1)	0.0252 (8)	−0.0020 (7)	−0.0021 (7)	0.0054 (8)
C11	0.0241 (8)	0.0298 (8)	0.0297 (9)	−0.0005 (6)	−0.0043 (7)	−0.0017 (7)
C12	0.0271 (9)	0.041 (1)	0.0326 (9)	−0.0094 (7)	−0.0002 (7)	0.0057 (8)
C13	0.0322 (9)	0.037 (1)	0.0281 (8)	−0.0025 (7)	−0.0028 (7)	0.0061 (8)
C14	0.033 (1)	0.076 (1)	0.042 (1)	−0.0099 (9)	−0.0152 (9)	0.017 (1)

Geometric parameters (Å, º)

O1—C1	1.311 (2)	C5—H4	0.95
O1—H1	0.90	C6—C7	1.380 (3)
O2—C1	1.241 (2)	C7—H5	0.95
O3—C3	1.355 (2)	C8—C9	1.383 (3)
O3—H2	0.86	C8—C13	1.397 (3)
O4—C11	1.367 (2)	C9—C10	1.388 (3)
O4—C14	1.427 (3)	C9—H6	0.97
N1—N2	1.260 (2)	C10—C11	1.388 (3)
N1—C6	1.432 (2)	C10—H7	0.99
N2—C8	1.424 (2)	C11—C12	1.392 (3)
C1—C2	1.462 (3)	C12—C13	1.374 (3)
C2—C3	1.403 (2)	C12—H8	0.96
C2—C7	1.400 (2)	C13—H9	0.98
C3—C4	1.398 (3)	C14—H10	0.99
C4—C5	1.372 (3)	C14—H11	1.03
C4—H3	0.96	C14—H12	0.93
C5—C6	1.401 (2)
O1···O2^i	2.631 (2)	O3···C4^vi	3.487 (2)
O1···H12^ii	2.8133	O4···H2^viii	2.4561
O1···H1^i	2.9916	O4···N1^ix	3.598 (3)
O1···N2^iii	3.258 (2)	N1···H6^vi	2.9758
O1···C3^iv	3.294 (2)	N2···H6^vi	2.7898
O1···C5^iii	3.341 (2)	N2···C9^vi	3.576 (3)
O1···C4^iv	3.419 (2)	C1···H1^i	2.6617
O1···O3^iv	3.425 (2)	C1···C3^iv	3.295 (3)
O1···C14^ii	3.436 (3)	C1···C2^iv	3.346 (3)
O1···C1^i	3.508 (2)	C1···C5^iii	3.522 (3)
O1···C6^iii	3.571 (2)	C2···C2^iv	3.393 (4)
O2···H1^i	1.7325	C2···C5^vi	3.581 (3)
O2···H12^v	2.7520	C3···H3^vi	2.7838
O2···O4^v	3.136 (2)	C3···H4^vi	3.0344
O2···O2^i	3.251 (3)	C3···C4^vi	3.437 (3)
O2···C1^i	3.334 (2)	C3···C5^vi	3.567 (3)
O2···C7^iv	3.376 (2)	C4···H4^vi	3.0178
O2···C6^iv	3.405 (2)	C11···H11^vi	3.0049
O2···C14^v	3.409 (3)	H1···H1^i	2.4915
O2···C4^iii	3.514 (2)	H1···H12^ii	2.5136
O2···C2^iv	3.525 (2)	H2···H3^vi	2.6843
O2···C5^iii	3.569 (2)	H3···H12^x	2.4392
O3···H3^vi	2.6076	H5···H8^xi	2.5198
O3···H11^vii	2.9674	H8···H10^iii	2.6201
O3···O4^v	3.003 (2)
C1—O1—H1	111.5	C6—C7—H5	119.7
C3—O3—H2	107.2	N2—C8—C9	114.8 (2)
C11—O4—C14	117.1 (2)	N2—C8—C13	125.8 (2)
N2—N1—C6	112.2 (2)	C9—C8—C13	119.4 (2)
N1—N2—C8	115.1 (2)	C8—C9—C10	121.4 (2)
O1—C1—O2	122.7 (2)	C8—C9—H6	119.3
O1—C1—C2	115.2 (2)	C10—C9—H6	119.2
O2—C1—C2	122.1 (2)	C9—C10—C11	118.6 (2)
C1—C2—C3	120.0 (2)	C9—C10—H7	119.9
C1—C2—C7	120.7 (2)	C11—C10—H7	121.5
C3—C2—C7	119.3 (2)	O4—C11—C10	124.0 (2)
O3—C3—C2	124.3 (2)	O4—C11—C12	115.7 (2)
O3—C3—C4	116.3 (2)	C10—C11—C12	120.3 (2)
C2—C3—C4	119.3 (2)	C11—C12—C13	120.7 (2)
C3—C4—C5	120.6 (2)	C11—C12—H8	119.7
C3—C4—H3	118.5	C13—C12—H8	119.5
C5—C4—H3	120.9	C8—C13—C12	119.6 (2)
C4—C5—C6	120.5 (2)	C8—C13—H9	118.6
C4—C5—H4	119.0	C12—C13—H9	121.8
C6—C5—H4	120.5	O4—C14—H10	110.6
N1—C6—C5	123.9 (2)	O4—C14—H11	110.1
N1—C6—C7	116.7 (2)	O4—C14—H12	106.0
C5—C6—C7	119.4 (2)	H10—C14—H11	112.0
C2—C7—C6	120.8 (2)	H10—C14—H12	109.7
C2—C7—H5	119.5	H11—C14—H12	108.2
O1—C1—C2—C3	−178.8 (2)	C1—C2—C3—C4	−178.5 (2)
O1—C1—C2—C7	0.8 (3)	C1—C2—C7—C6	−178.9 (2)
O2—C1—C2—C3	0.9 (3)	C2—C3—C4—C5	−2.2 (3)
O2—C1—C2—C7	−179.4 (2)	C2—C7—C6—C5	−3.0 (3)
O3—C3—C2—C1	1.2 (3)	C3—C2—C7—C6	0.8 (3)
O3—C3—C2—C7	−178.5 (2)	C3—C4—C5—C6	−0.1 (3)
O3—C3—C4—C5	178.1 (2)	C4—C3—C2—C7	1.8 (3)
O4—C11—C10—C9	179.4 (2)	C4—C5—C6—C7	2.7 (3)
O4—C11—C12—C13	−179.3 (2)	C6—N1—N2—C8	179.9 (2)
N1—N2—C8—C9	176.4 (2)	C8—C9—C10—C11	−0.7 (3)
N1—N2—C8—C13	−2.9 (3)	C8—C13—C12—C11	0.5 (3)
N1—C6—C5—C4	−177.0 (2)	C9—C8—C13—C12	−1.6 (3)
N1—C6—C7—C2	176.7 (2)	C9—C10—C11—C12	−0.4 (3)
N2—N1—C6—C5	8.5 (3)	C10—C9—C8—C13	1.7 (3)
N2—N1—C6—C7	−171.1 (2)	C10—C11—O4—C14	1.5 (3)
N2—C8—C9—C10	−177.6 (2)	C10—C11—C12—C13	0.5 (3)
N2—C8—C13—C12	177.6 (2)	C12—C11—O4—C14	−178.6 (2)

Symmetry codes: (i) −x+2, −y, −z+2; (ii) −x+3/2, −y, z+3/2; (iii) x, y, z+1; (iv) −x+2, −y, −z+1; (v) x+1/2, y, −z+1/2; (vi) x, −y+1/2, z+1/2; (vii) x+1/2, −y+1/2, −z; (viii) x−1/2, y, −z+1/2; (ix) −x+3/2, −y, z−1/2; (x) x+1/2, y, −z−1/2; (xi) −x+3/2, −y, z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2^i	0.90	1.73	2.631 (2)	176
O3—H2···O2	0.86	1.87	2.630 (2)	146
O3—H2···O4^v	0.86	2.46	3.003 (2)	122

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