o-Benzoquinone dioxime

Abstract

The title compound, C₆H₆N₂O₂, was obtained as a product of an in vitro study of the metabolism of benzofuroxan. The molecule exhibits a amphi configuration of the oxime groups C=N—OH. One oxime group is involved in the formation of a strong intra­molecular O—H⋯N hydrogen bond, while another links mol­ecules into zigzag chains along the c axis via inter­molecular O—H⋯N hydrogen bonds.

Related literature

For details of the synthesis, see: Grosa et al. (2004 ▶). For a related structure, see: Mégnamisi-Bélombé & Endres (1985 ▶).

Experimental

Crystal data

• C₆H₆N₂O₂

• M _r = 138.13

• Orthorhombic,

• a = 15.009 (5) Å

• b = 3.8181 (13) Å

• c = 10.694 (3) Å

• V = 612.8 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 0.12 mm⁻¹

• T = 293 K

• 0.24 × 0.12 × 0.04 mm

Data collection

• Siemens–Bruker APEX diffractometer

• Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.856, T _max = 1.000

• 2330 measured reflections

• 468 independent reflections

• 418 reflections with I > 2σ(I)

• R _int = 0.055

• θ_max = 23.3°

• 11 standard reflections every 60 min intensity decay: none

Refinement

• R[F ² > 2σ(F ²)] = 0.034

• wR(F ²) = 0.082

• S = 1.01

• 468 reflections

• 99 parameters

• 1 restraint

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.19 e Å⁻³

• Δρ_min = −0.13 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N2i	0.85 (7)	1.92 (7)	2.745 (4)	162 (6)
O2—H2⋯N1	1.06 (8)	1.57 (8)	2.532 (4)	147 (6)

Symmetry code: (i) .

supplementary crystallographic information

Comment

The title compound, o-benzoquinone dioxime, has been obtained according to Grosa et al. (2004). In the C1—C6 ring the C3-C4 and C5-C6 bond distances correspond to formal double bonds (1.336 (5) Å av.). Also the C1-N1 and C2-N2 distances agree with a double bond character (1.304 (5) Å av.). Noteworthy is the presence of a strong intramolecular hydrogen bond O2-H2···N2 that probably stabilize the syn form of the dioxime. A further intermolecular hydrogen bond O1-H1..N2 forms chains of molecules. O-benzoquinone dioxime is known as an excellent ligand which forms bis-chelated transition metal complexes especially with the dipositive metal ions of the Ni triad (cf. Mégnamisi-Bélombé & Endres, 1985).

Experimental

The o-benzoquinone dioxime has been otained according to Grosa et al. (2004)

Refinement

A very small and poorly diffracting crystal has been used; it was not possible to obtain a better crystal because it is a product of a metabolism. C-bound H atoms were placed in geometrically idealized positions (C—H = 0.93 Å), and refined as riding, with U_iso(H) = 1.2U_eq(C). Two O-bound H atoms were located on a difference map and refined isotropically. A restraint has been imposed on the planarity of the hexagonal ring. In the absence of any significant anomalous scatterers in the molecule, 368 Friedel pairs were merged before the final refinement.

Figures

Fig. 1.

The molecular structure of trhe title compound showing the atomic numbering and 50% of probability displacements ellipsoids.

Crystal data

C6H6N2O2	Dx = 1.497 Mg m−3
Mr = 138.13	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21	Cell parameters from 500 reflections
a = 15.009 (5) Å	θ = 2.7–23.3°
b = 3.8181 (13) Å	µ = 0.12 mm−1
c = 10.694 (3) Å	T = 293 K
V = 612.8 (4) Å3	Prism, orange
Z = 4	0.24 × 0.12 × 0.04 mm
F(000) = 288

Data collection

Siemens–Bruker APEX diffractometer	418 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.055
graphite	θmax = 23.3°, θmin = 2.7°
φ scans	h = −16→16
Absorption correction: multi-scan (Blessing, 1995)	k = −4→3
Tmin = 0.856, Tmax = 1.000	l = −11→11
2330 measured reflections	11 standard reflections every 60 min
468 independent reflections	intensity decay: none

Refinement

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.082	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ2(Fo2) + (0.0605P)2] where P = (Fo2 + 2Fc2)/3
468 reflections	(Δ/σ)max < 0.001
99 parameters	Δρmax = 0.19 e Å−3
1 restraint	Δρmin = −0.13 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
C1	0.6109 (3)	0.3317 (8)	0.4796 (3)	0.0377 (8)
C2	0.5481 (2)	0.2457 (9)	0.5795 (3)	0.0377 (8)
C3	0.5843 (3)	0.0751 (9)	0.6896 (3)	0.0479 (10)
H3A	0.5461	0.0119	0.7543	0.057*
C4	0.6706 (3)	0.0072 (9)	0.6998 (3)	0.0520 (12)
H4A	0.6919	−0.1043	0.7711	0.062*
C5	0.7312 (3)	0.1027 (10)	0.6031 (3)	0.0532 (10)
H5A	0.7916	0.0552	0.6128	0.064*
C6	0.7028 (3)	0.2599 (9)	0.4981 (3)	0.0461 (9)
H6A	0.7437	0.3225	0.4368	0.055*
N1	0.5761 (2)	0.4735 (7)	0.3794 (3)	0.0426 (8)
N2	0.4629 (2)	0.3068 (8)	0.5828 (3)	0.0489 (8)
O1	0.6388 (2)	0.5573 (8)	0.2905 (2)	0.0561 (8)
H1	0.603 (4)	0.638 (17)	0.236 (6)	0.11 (2)*
O2	0.4235 (2)	0.4598 (7)	0.4801 (2)	0.0584 (9)
H2	0.477 (5)	0.541 (17)	0.422 (6)	0.13 (2)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.045 (2)	0.0412 (18)	0.0267 (15)	−0.0013 (15)	−0.0039 (15)	−0.0047 (13)
C2	0.043 (2)	0.0426 (19)	0.0278 (15)	−0.0044 (16)	0.0022 (16)	−0.0053 (14)
C3	0.067 (3)	0.046 (2)	0.0306 (17)	−0.0030 (17)	0.0005 (18)	−0.0007 (18)
C4	0.072 (3)	0.050 (2)	0.035 (2)	0.004 (2)	−0.018 (2)	0.0031 (14)
C5	0.054 (3)	0.055 (2)	0.050 (2)	0.0067 (19)	−0.012 (2)	−0.0059 (17)
C6	0.047 (2)	0.053 (2)	0.0382 (18)	0.0039 (18)	−0.0018 (17)	−0.0051 (17)
N1	0.041 (2)	0.0576 (19)	0.0294 (14)	−0.0035 (13)	0.0044 (16)	−0.0011 (12)
N2	0.051 (2)	0.0646 (18)	0.0306 (14)	0.0003 (17)	0.0034 (15)	−0.0015 (16)
O1	0.0470 (18)	0.091 (2)	0.0303 (12)	−0.0017 (14)	0.0032 (14)	0.0104 (13)
O2	0.046 (2)	0.090 (2)	0.0393 (14)	0.0042 (14)	−0.0021 (14)	0.0018 (13)

Geometric parameters (Å, °)

C1—N1	1.309 (5)	C4—H4A	0.9300
C1—C6	1.420 (5)	C5—C6	1.342 (5)
C1—C2	1.462 (5)	C5—H5A	0.9300
C2—N2	1.299 (4)	C6—H6A	0.9300
C2—C3	1.450 (5)	N1—O1	1.375 (4)
C3—C4	1.326 (6)	N2—O2	1.377 (4)
C3—H3A	0.9300	O1—H1	0.85 (7)
C4—C5	1.425 (6)	O2—H2	1.06 (8)
N1—C1—C6	125.5 (3)	C5—C4—H4A	119.5
N1—C1—C2	115.8 (3)	C6—C5—C4	121.2 (4)
C6—C1—C2	118.7 (3)	C6—C5—H5A	119.4
N2—C2—C3	115.3 (3)	C4—C5—H5A	119.4
N2—C2—C1	127.8 (3)	C5—C6—C1	120.8 (4)
C3—C2—C1	116.9 (3)	C5—C6—H6A	119.6
C4—C3—C2	121.4 (4)	C1—C6—H6A	119.6
C4—C3—H3A	119.3	C1—N1—O1	112.9 (3)
C2—C3—H3A	119.3	C2—N2—O2	118.5 (3)
C3—C4—C5	120.9 (3)	N1—O1—H1	97 (4)
C3—C4—H4A	119.5	N2—O2—H2	105 (4)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N2i	0.85 (7)	1.92 (7)	2.745 (4)	162 (6)
O2—H2···N1	1.06 (8)	1.57 (8)	2.532 (4)	147 (6)

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