2-[(E)-(5-tert-Butyl-2-hydroxy­phen­yl)­diazen­yl]benzoic acid

The title compound, C₁₇H₁₈N₂O₃, is approximately planar, owing in part to an intra­molecular bifurcated O—H...(N,O) hydrogen bond; the dihedral angle between the two aromatic rings is 23.86 (9)°. In the crystal struture, centrosymmetrically related mol­ecules associate into dimers via the eight-membered carboxyl­ate {...H—O—C=O}₂ synthon.

Key indicators

• Single-crystal X-ray study
• T = 98 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.059
• wR factor = 0.144
• Data-to-parameter ratio = 15.0

checkCIF/PLATON results

No syntax errors found



Alert level C
            Value of measurement temperature given =    98.000
            Value of melting point given =     0.000
SHFSU01_ALERT_2_C  Test not performed. _refine_ls_shift/su_max and
            _refine_ls_shift/esd_max not present.
            Absolute value of the parameter shift to su ratio given   0.001
PLAT432_ALERT_2_C Short Inter X...Y Contact  C3     ..  C9      ..       3.18 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   1 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

2-Aminobenzoic acid reacts with 4-tert-butyl-phenol to form the title compound (I), Fig. 1, which was prepared during an on-going study of the coordination chemistry of such molecules (Basu Baul et al., 2007) with organotin species (Tiekink, 1991; Willem et al., 1998). The molecule is approximately planar as seen in the value of the dihedral angle formed between the two aromatic residues of 23.86 (9)°. Small twists in the molecule are indicated by the N2–N1–C2–C3 and N1–N2–C8–C9 torsion angles of -18.1 (3) and -2.6 (3)°, respectively. The conformation is stabilized by intramolecular O—H···O and O—H···N hydrogen bonding interactions, Table 1. In the crystal packing, centrosymmetric molecules associate via the eight-membered carboxylate {···H—O—C=O}₂ synthon.

Related literature

For a related structure, see: Basu Baul et al. (2007). For background, see: Willem et al. (1998). For reviews of organotin carboxylates, see: Tiekink (1991).

S2. Experimental

2-Aminobenzoic acid (2.0 g, 14.58 mmol) was mixed with HCl (5 ml) and water (20 ml) and digested in a water bath for 1 h. The hydrochloride was cooled to 5 ° C and diazotized with ice-cold aqueous NaNO₂ solution (1.1 g, 15.95 mmol, 10 ml). The cold diazonium salt solution was added slowly to 4-tert-butyl-phenol (2.19 g, 14.58 mmol), previously dissolved in a NaOH solution (4.0 g) in water (100 ml) under vigorous stirring. A deep-red colour developed almost immediately and stirring was continued for 1 h. The reaction mixture was kept overnight in a refrigerator followed by 2 h at room temperature and then acidified with acetic acid. The brown coloured precipitate was filtered, washed several times with water to remove soluble starting materials, and then dried in air. The dried mass was suspended in water, dissolved in dilute NaOH solution and filtered. The filtrate was collected, precipitated with dilute acetic acid and filtered. The orange-red precipitate was then washed thoroughly with water until the washings were neutral and dried in air. The dried precipitate was boiled in hot hexane, filtered and dried in vacuo. Several recrystallization of the precipitate from methanol yielded red plates of (I) (2.50 g, 40.3%), m.pt. 453–455 K. Elemental analysis, found: C 68.54, H 6.01, N 9.49%; C₁₇H₁₈N₂O₃ requires C 68.44, H 6.08, N 9.39%. IR (KBr, cm-1): 1699 ν(OCO)_asym. ¹H NMR (CDCl₃, 400.13 MHz, see Fig. 1 for numbering scheme): δ H: 10.7 [br, 2H, OH & CO₂H], 8.15 [d, 8 Hz, 1H, H6], 7.92 [d, 8 Hz, 1H, H3], 7.78 [d, 2.5 Hz, 1H, H13], 7.58 [t, 8 Hz, 1H, H4], 7.42 [t, 8 Hz, 1H, H5], 7.34 [dd, 2.5, 8 Hz, 1H, H11], 6.96 [d, 8 Hz, 1H, H10], 1.19 [s, 9H, CH₃] p.p.m. ¹³C NMR (CDCl₃, 100.62 MHz): δ C: 170.6 [CO₂], 152.2 [C9], 149.8 [C2], 142.8 [C8], 137.9 [C11], 133.3 [C13], 132.7 [C4], 132.5 [C6], 130.3 [C5], 129.6 [C12'], 125.9 [C1], 119.0 [C10], 116.6 [C3], 34.4 [C14], 31.6 [CH₃] p.p.m.

S3. Refinement

All C-bound H atoms were included in the riding-model approximation, with C—H = 0.95 to 0.98 Å, and with U_iso(H) = 1.2–1.5U_eq(C). The hydroxyl-H atom were located from a difference map and included so that O—H = 0.84 Å and U_iso(H) = 1.5U_eq(O).

Computing details

Data collection: CrystalClear (Rigaku Americas Corporation, 2005); cell refinement: CrystalClear (Rigaku Americas Corporation, 2005); data reduction: CrystalClear (Rigaku Americas Corporation, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. Molecular structure of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.

2-[(E)-(5-tert-butyl-2-hydroxyphenyl)diazenyl]benzoic acid

Crystal data

C17H18N2O3	F(000) = 632
Mr = 298.33	Dx = 1.339 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7951 reflections
a = 5.9052 (19) Å	θ = 2.1–40.6°
b = 10.872 (4) Å	µ = 0.09 mm^−1
c = 23.126 (8) Å	T = 98 K
β = 94.432 (4)°	Prism, red
V = 1480.3 (9) Å^3	0.35 × 0.16 × 0.08 mm
Z = 4

Data collection

Rigaku Saturn724 (2x2 bin mode) diffractometer	2610 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.065
Graphite monochromator	θmax = 26.5°, θmin = 2.6°
Detector resolution: 28.5714 pixels mm^-1	h = −7→7
dtprofit.ref scans	k = −13→10
8445 measured reflections	l = −28→27
3068 independent reflections

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)] = 0.059	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.144	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0534P)^2 + 0.6036P] where P = (Fo^2 + 2Fc^2)/3
3068 reflections	(Δ/σ)max < 0.001
205 parameters	Δρmax = 0.24 e Å^−3
2 restraints	Δρmin = −0.31 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	0.8680 (2)	0.51703 (14)	0.43659 (6)	0.0263 (3)
O2	0.7565 (3)	0.39227 (16)	0.50557 (6)	0.0321 (4)
H2O	0.8640	0.4274	0.5250	0.048*
O3	1.0671 (2)	0.59362 (14)	0.33194 (6)	0.0246 (3)
H3O	0.9599	0.5542	0.3451	0.037*
N1	0.7361 (2)	0.43713 (16)	0.32732 (6)	0.0190 (3)
N2	0.7593 (2)	0.40523 (16)	0.27524 (6)	0.0191 (4)
C1	0.5577 (3)	0.37647 (19)	0.41419 (8)	0.0201 (4)
C2	0.5548 (3)	0.37664 (18)	0.35309 (8)	0.0185 (4)
C3	0.3792 (3)	0.31732 (19)	0.32013 (8)	0.0199 (4)
H3	0.3774	0.3177	0.2790	0.024*
C4	0.2083 (3)	0.25820 (19)	0.34670 (8)	0.0218 (4)
H4	0.0892	0.2186	0.3238	0.026*
C5	0.2102 (3)	0.2566 (2)	0.40711 (8)	0.0243 (4)
H5	0.0928	0.2157	0.4254	0.029*
C6	0.3842 (3)	0.3148 (2)	0.44028 (8)	0.0237 (4)
H6	0.3857	0.3128	0.4814	0.028*
C7	0.7425 (3)	0.43611 (19)	0.45205 (7)	0.0204 (4)
C8	0.9426 (3)	0.46168 (18)	0.25033 (7)	0.0179 (4)
C9	1.0885 (3)	0.55091 (18)	0.27794 (7)	0.0188 (4)
C10	1.2692 (3)	0.59442 (19)	0.24792 (8)	0.0226 (4)
H10	1.3672	0.6559	0.2650	0.027*
C11	1.3068 (3)	0.54898 (19)	0.19368 (8)	0.0218 (4)
H11	1.4315	0.5800	0.1745	0.026*
C12	1.1679 (3)	0.45878 (19)	0.16583 (8)	0.0195 (4)
C13	0.9861 (3)	0.41778 (19)	0.19516 (7)	0.0201 (4)
H13	0.8872	0.3577	0.1772	0.024*
C14	1.2258 (3)	0.4010 (2)	0.10821 (8)	0.0221 (4)
C15	1.3827 (3)	0.2902 (2)	0.12276 (9)	0.0285 (5)
H15A	1.4224	0.2510	0.0867	0.043*
H15B	1.3040	0.2306	0.1459	0.043*
H15C	1.5213	0.3183	0.1449	0.043*
C16	1.3498 (4)	0.4929 (2)	0.07107 (9)	0.0350 (5)
H16A	1.3845	0.4533	0.0347	0.052*
H16B	1.4913	0.5194	0.0924	0.052*
H16C	1.2524	0.5646	0.0624	0.052*
C17	1.0117 (3)	0.3565 (2)	0.07259 (8)	0.0300 (5)
H17A	1.0544	0.3198	0.0363	0.045*
H17B	0.9099	0.4263	0.0639	0.045*
H17C	0.9341	0.2948	0.0948	0.045*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0322 (7)	0.0266 (8)	0.0198 (6)	−0.0063 (6)	−0.0008 (5)	0.0028 (6)
O2	0.0389 (8)	0.0371 (10)	0.0193 (7)	−0.0135 (7)	−0.0048 (6)	0.0059 (6)
O3	0.0284 (7)	0.0242 (8)	0.0218 (6)	−0.0050 (6)	0.0052 (5)	−0.0054 (6)
N1	0.0187 (7)	0.0213 (9)	0.0171 (7)	0.0019 (6)	0.0024 (5)	0.0007 (6)
N2	0.0185 (7)	0.0208 (9)	0.0181 (7)	0.0017 (6)	0.0029 (6)	0.0004 (6)
C1	0.0215 (9)	0.0184 (10)	0.0208 (9)	0.0024 (7)	0.0033 (7)	−0.0002 (7)
C2	0.0187 (8)	0.0165 (9)	0.0207 (8)	0.0032 (7)	0.0045 (6)	0.0008 (7)
C3	0.0208 (8)	0.0192 (10)	0.0200 (8)	0.0044 (7)	0.0031 (7)	−0.0011 (7)
C4	0.0182 (8)	0.0196 (10)	0.0274 (9)	0.0014 (7)	0.0009 (7)	−0.0014 (8)
C5	0.0222 (9)	0.0263 (11)	0.0252 (9)	−0.0010 (8)	0.0067 (7)	0.0047 (8)
C6	0.0283 (9)	0.0244 (11)	0.0185 (8)	0.0016 (8)	0.0034 (7)	0.0005 (8)
C7	0.0240 (9)	0.0210 (10)	0.0166 (8)	0.0024 (8)	0.0041 (7)	0.0001 (7)
C8	0.0173 (8)	0.0188 (10)	0.0177 (8)	0.0006 (7)	0.0021 (6)	0.0011 (7)
C9	0.0217 (8)	0.0152 (9)	0.0194 (8)	0.0016 (7)	0.0010 (6)	−0.0010 (7)
C10	0.0240 (9)	0.0184 (10)	0.0254 (9)	−0.0033 (7)	0.0018 (7)	0.0003 (8)
C11	0.0203 (8)	0.0201 (10)	0.0256 (9)	−0.0014 (7)	0.0050 (7)	0.0043 (8)
C12	0.0200 (8)	0.0187 (10)	0.0199 (8)	0.0019 (7)	0.0025 (6)	0.0021 (7)
C13	0.0198 (8)	0.0215 (10)	0.0189 (8)	−0.0016 (7)	0.0006 (7)	−0.0011 (7)
C14	0.0212 (9)	0.0260 (11)	0.0197 (9)	−0.0016 (8)	0.0060 (7)	0.0003 (8)
C15	0.0262 (9)	0.0303 (12)	0.0292 (10)	0.0024 (8)	0.0040 (8)	−0.0069 (9)
C16	0.0397 (12)	0.0378 (14)	0.0295 (10)	−0.0080 (10)	0.0157 (9)	0.0012 (10)
C17	0.0250 (9)	0.0468 (15)	0.0185 (9)	0.0007 (9)	0.0039 (7)	−0.0049 (9)

Geometric parameters (Å, º)

O1—C7	1.221 (2)	C9—C10	1.400 (3)
O2—C7	1.323 (2)	C10—C11	1.382 (3)
O2—H2O	0.84	C10—H10	0.9500
O3—C9	1.348 (2)	C11—C12	1.403 (3)
O3—H3O	0.84	C11—H11	0.9500
N1—N2	1.271 (2)	C12—C13	1.387 (2)
N1—C2	1.426 (2)	C12—C14	1.536 (3)
N2—C8	1.406 (2)	C13—H13	0.9500
C1—C6	1.400 (3)	C14—C17	1.533 (3)
C1—C2	1.412 (2)	C14—C16	1.539 (3)
C1—C7	1.494 (3)	C14—C15	1.541 (3)
C2—C3	1.396 (3)	C15—H15A	0.9800
C3—C4	1.380 (3)	C15—H15B	0.9800
C3—H3	0.9500	C15—H15C	0.9800
C4—C5	1.396 (3)	C16—H16A	0.9800
C4—H4	0.9500	C16—H16B	0.9800
C5—C6	1.387 (3)	C16—H16C	0.9800
C5—H5	0.9500	C17—H17A	0.9800
C6—H6	0.9500	C17—H17B	0.9800
C8—C13	1.404 (2)	C17—H17C	0.9800
C8—C9	1.417 (3)
C7—O2—H2O	109.0	C10—C11—C12	122.50 (17)
C9—O3—H3O	106.6	C10—C11—H11	118.7
N2—N1—C2	114.19 (16)	C12—C11—H11	118.7
N1—N2—C8	114.34 (15)	C13—C12—C11	116.58 (17)
C6—C1—C2	118.67 (17)	C13—C12—C14	121.71 (17)
C6—C1—C7	118.77 (16)	C11—C12—C14	121.52 (16)
C2—C1—C7	122.54 (16)	C12—C13—C8	122.54 (17)
C3—C2—C1	119.78 (17)	C12—C13—H13	118.7
C3—C2—N1	122.33 (16)	C8—C13—H13	118.7
C1—C2—N1	117.88 (16)	C17—C14—C12	111.46 (15)
C4—C3—C2	120.65 (17)	C17—C14—C16	108.24 (17)
C4—C3—H3	119.7	C12—C14—C16	111.47 (17)
C2—C3—H3	119.7	C17—C14—C15	109.10 (18)
C3—C4—C5	120.12 (17)	C12—C14—C15	107.52 (15)
C3—C4—H4	119.9	C16—C14—C15	109.01 (17)
C5—C4—H4	119.9	C14—C15—H15A	109.5
C6—C5—C4	119.72 (18)	C14—C15—H15B	109.5
C6—C5—H5	120.1	H15A—C15—H15B	109.5
C4—C5—H5	120.1	C14—C15—H15C	109.5
C5—C6—C1	121.06 (17)	H15A—C15—H15C	109.5
C5—C6—H6	119.5	H15B—C15—H15C	109.5
C1—C6—H6	119.5	C14—C16—H16A	109.5
O1—C7—O2	122.55 (17)	C14—C16—H16B	109.5
O1—C7—C1	124.99 (16)	H16A—C16—H16B	109.5
O2—C7—C1	112.46 (17)	C14—C16—H16C	109.5
C13—C8—N2	115.13 (16)	H16A—C16—H16C	109.5
C13—C8—C9	119.64 (16)	H16B—C16—H16C	109.5
N2—C8—C9	125.11 (16)	C14—C17—H17A	109.5
O3—C9—C10	118.24 (17)	C14—C17—H17B	109.5
O3—C9—C8	123.79 (16)	H17A—C17—H17B	109.5
C10—C9—C8	117.94 (17)	C14—C17—H17C	109.5
C11—C10—C9	120.77 (18)	H17A—C17—H17C	109.5
C11—C10—H10	119.6	H17B—C17—H17C	109.5
C9—C10—H10	119.6
C2—N1—N2—C8	−178.01 (15)	C13—C8—C9—O3	−176.45 (17)
C6—C1—C2—C3	0.8 (3)	N2—C8—C9—O3	−0.7 (3)
C7—C1—C2—C3	178.85 (18)	C13—C8—C9—C10	1.6 (3)
C6—C1—C2—N1	−178.37 (17)	N2—C8—C9—C10	177.41 (17)
C7—C1—C2—N1	−0.4 (3)	O3—C9—C10—C11	176.50 (17)
N2—N1—C2—C3	−18.1 (3)	C8—C9—C10—C11	−1.7 (3)
N2—N1—C2—C1	161.07 (17)	C9—C10—C11—C12	0.4 (3)
C1—C2—C3—C4	−0.1 (3)	C10—C11—C12—C13	1.0 (3)
N1—C2—C3—C4	179.05 (17)	C10—C11—C12—C14	−174.16 (18)
C2—C3—C4—C5	−0.4 (3)	C11—C12—C13—C8	−1.0 (3)
C3—C4—C5—C6	0.1 (3)	C14—C12—C13—C8	174.10 (17)
C4—C5—C6—C1	0.6 (3)	N2—C8—C13—C12	−176.47 (17)
C2—C1—C6—C5	−1.1 (3)	C9—C8—C13—C12	−0.3 (3)
C7—C1—C6—C5	−179.17 (18)	C13—C12—C14—C17	32.4 (3)
C6—C1—C7—O1	−160.29 (19)	C11—C12—C14—C17	−152.69 (19)
C2—C1—C7—O1	21.7 (3)	C13—C12—C14—C16	153.50 (18)
C6—C1—C7—O2	19.2 (3)	C11—C12—C14—C16	−31.6 (3)
C2—C1—C7—O2	−158.82 (18)	C13—C12—C14—C15	−87.1 (2)
N1—N2—C8—C13	173.37 (16)	C11—C12—C14—C15	87.8 (2)
N1—N2—C8—C9	−2.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3O···N1	0.84	1.86	2.587 (2)	144
O3—H3O···O1	0.84	2.26	2.894 (2)	132
O2—H2O···O1^i	0.84	1.86	2.687 (2)	170

Symmetry code: (i) −x+2, −y+1, −z+1.