4-Hydro­xy-ONN-azoxy­benzene

The oxidation of 4-hydroxy­azo­benzene provided a mixture of two azoxy compounds, which were separated by column chromatography. The isomer with the higher melting point appeared to belong to the α (ONN) series, as determined by X-ray diffraction. The mol­ecule, C₁₂H₁₀N₂O₂, is almost planar. The benzene rings are twisted by 11.7 (2) (substituted) and 4.1 (1)° (unsubstituted) with respect to the ONN plane. The mol­ecules are connected to one another by strong O—H...O hydrogen bonds forming chains extended along [001], which are bound by much weaker C—H...O hydrogen bonds forming layers in the bc plane.

Computing details

Data collection: KUMA Diffraction Software (Kuma, 1998); cell refinement: KUMA Diffraction Software; data reduction: KUMA Diffraction Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1990); software used to prepare material for publication: SHELXL97.

(IIa)

Crystal data

C12H10N2O2	Dx = 1.372 Mg m^−3 Dm = 1.37 (1) Mg m^−3 Dm measured by flotation
Mr = 214.22	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 21 reflections
a = 7.187 (1) Å	θ = 8–11°
b = 11.261 (2) Å	µ = 0.10 mm^−1
c = 12.812 (3) Å	T = 293 K
V = 1036.9 (3) Å^3	Plate, yellow
Z = 4	0.5 × 0.4 × 0.3 mm
F(000) = 448

Data collection

KUMA KM–4 diffractometer	Rint = 0.029
Radiation source: fine-focus sealed tube	θmax = 30.1°, θmin = 2.4°
Graphite monochromator	h = −10→10
ω–θ scans	k = −15→15
2796 measured reflections	l = −18→18
1729 independent reflections	2 standard reflections every 50 reflections
1026 reflections with I > 2σ(I)	intensity decay: 0.5%

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)] = 0.034	Hydrogen site location: difference Fourier map
wR(F^2) = 0.096	All H atoms refined isotropically
S = 0.99	Calculated w = 1/[σ^2(Fo^2) + (0.0252P)^2 + 0.113P] where P = (Fo^2 + 2Fc^2)/3
1729 reflections	(Δ/σ)max < 0.001
185 parameters	Δρmax = 0.11 e Å^−3
0 restraints	Δρmin = −0.13 e Å^−3

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

	x	y	z	Uiso*/Ueq
N2	0.2024 (3)	0.24506 (17)	0.84313 (14)	0.0548 (5)
N1	0.1457 (3)	0.21220 (18)	0.93209 (14)	0.0521 (5)
O2	0.2274 (3)	0.70176 (16)	0.68493 (14)	0.0673 (6)
O1	0.0781 (3)	0.27976 (13)	1.00334 (14)	0.0608 (5)
C1	0.1961 (4)	0.3645 (2)	0.81248 (16)	0.0514 (6)
C2	0.2936 (4)	0.3844 (2)	0.72042 (17)	0.0634 (7)
C3	0.3056 (4)	0.4951 (2)	0.67680 (18)	0.0626 (7)
C4	0.2184 (4)	0.5901 (2)	0.72317 (16)	0.0523 (6)
C5	0.1148 (4)	0.5715 (2)	0.81343 (18)	0.0569 (7)
C6	0.1035 (4)	0.4607 (2)	0.85810 (17)	0.0544 (6)
C1'	0.1562 (3)	0.0855 (2)	0.95302 (16)	0.0491 (6)
C6'	0.1027 (4)	0.0457 (2)	1.04995 (19)	0.0619 (7)
C5'	0.1099 (5)	−0.0739 (3)	1.0707 (2)	0.0736 (9)
C4'	0.1677 (5)	−0.1527 (3)	0.9970 (2)	0.0719 (8)
C3'	0.2199 (5)	−0.1121 (2)	0.89940 (19)	0.0722 (8)
C2'	0.2135 (4)	0.0072 (3)	0.87713 (19)	0.0625 (7)
H22	0.298 (6)	0.703 (3)	0.632 (3)	0.108 (12)*
H2	0.370 (5)	0.315 (3)	0.686 (3)	0.098 (10)*
H3	0.375 (4)	0.506 (2)	0.618 (2)	0.071 (8)*
H5	0.045 (3)	0.639 (2)	0.8410 (18)	0.061 (7)*
H6	0.026 (4)	0.445 (2)	0.920 (2)	0.066 (8)*
H6'	0.059 (4)	0.105 (2)	1.096 (2)	0.080 (9)*
H5'	0.059 (5)	−0.105 (3)	1.135 (3)	0.123 (13)*
H4'	0.163 (4)	−0.236 (2)	1.008 (2)	0.068 (7)*
H3'	0.254 (4)	−0.171 (2)	0.848 (2)	0.093 (10)*
H2'	0.246 (4)	0.038 (2)	0.808 (2)	0.074 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N2	0.0612 (13)	0.0648 (13)	0.0383 (9)	−0.0017 (12)	0.0060 (10)	−0.0019 (9)
N1	0.0550 (12)	0.0659 (13)	0.0355 (8)	−0.0005 (11)	−0.0017 (9)	−0.0047 (9)
O2	0.0893 (15)	0.0617 (11)	0.0508 (9)	0.0053 (11)	0.0132 (10)	0.0078 (8)
O1	0.0805 (12)	0.0664 (11)	0.0353 (6)	0.0122 (10)	0.0062 (9)	−0.0081 (9)
C1	0.0620 (15)	0.0522 (13)	0.0399 (10)	−0.0017 (13)	−0.0015 (12)	−0.0011 (10)
C2	0.0830 (19)	0.0648 (15)	0.0423 (11)	0.0008 (16)	0.0122 (14)	−0.0039 (11)
C3	0.0787 (19)	0.0697 (17)	0.0394 (11)	0.0032 (16)	0.0133 (14)	0.0017 (12)
C4	0.0625 (15)	0.0578 (14)	0.0367 (10)	−0.0004 (13)	−0.0017 (11)	0.0029 (10)
C5	0.0637 (16)	0.0615 (15)	0.0454 (12)	0.0065 (14)	0.0071 (13)	−0.0009 (11)
C6	0.0569 (15)	0.0663 (16)	0.0400 (11)	−0.0009 (13)	0.0064 (12)	0.0009 (11)
C1'	0.0537 (15)	0.0526 (14)	0.0410 (11)	0.0003 (12)	−0.0029 (11)	0.0019 (10)
C6'	0.0772 (19)	0.0671 (17)	0.0414 (12)	−0.0005 (15)	0.0088 (14)	−0.0037 (12)
C5'	0.106 (3)	0.0663 (17)	0.0486 (13)	−0.0125 (18)	0.0102 (17)	0.0082 (13)
C4'	0.101 (2)	0.0572 (15)	0.0577 (14)	−0.0097 (17)	0.0046 (18)	0.0062 (14)
C3'	0.101 (2)	0.0612 (16)	0.0546 (14)	0.0033 (17)	0.0127 (17)	−0.0036 (13)
C2'	0.0796 (19)	0.0662 (16)	0.0417 (11)	0.0044 (16)	0.0087 (14)	0.0024 (12)

Geometric parameters (Å, º)

N2—N1	1.266 (3)	C4—C5	1.391 (3)
N2—C1	1.402 (3)	C5—C6	1.375 (3)
N1—O1	1.284 (2)	C1'—C6'	1.375 (3)
N1—C1'	1.453 (3)	C1'—C2'	1.376 (3)
O2—C4	1.351 (3)	C6'—C5'	1.375 (4)
C1—C2	1.390 (3)	C5'—C4'	1.359 (4)
C1—C6	1.400 (3)	C4'—C3'	1.383 (4)
C2—C3	1.368 (4)	C3'—C2'	1.375 (4)
C3—C4	1.375 (3)
N1—N2—C1	121.5 (2)	C3—C4—C5	119.1 (2)
N2—N1—O1	126.1 (2)	C6—C5—C4	120.9 (2)
N2—N1—C1'	115.9 (2)	C5—C6—C1	120.0 (2)
O1—N1—C1'	118.0 (2)	C6'—C1'—C2'	120.9 (2)
C2—C1—C6	118.0 (2)	C6'—C1'—N1	118.2 (2)
C2—C1—N2	112.1 (2)	C2'—C1'—N1	120.9 (2)
C6—C1—N2	129.9 (2)	C1'—C6'—C5'	118.9 (2)
C3—C2—C1	121.7 (3)	C4'—C5'—C6'	121.1 (2)
C2—C3—C4	120.2 (2)	C5'—C4'—C3'	119.7 (3)
O2—C4—C3	123.1 (2)	C2'—C3'—C4'	120.1 (3)
O2—C4—C5	117.8 (2)	C1'—C2'—C3'	119.3 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H22···O1^i	0.85 (4)	1.88 (4)	2.722 (3)	170 (4)
C3′—H3′···O2^ii	0.97 (3)	2.54 (3)	3.456 (3)	158 (3)

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