(2Z,3Z)-Quinoxaline-2,3(1H,4H)-dione dioxime

The asymmetric unit of the title compound, C₈H₈N₄O₂, contains one half-mol­ecule; a twofold rotation axis bisects the molecule. An intra­molecular N—H⋯O hydrogen bond results in the formation of a five-membered ring, which displays an envelope conformation. In the crystal structure, inter­molecular O—H⋯N hydrogen bonds link the mol­ecules.

Related literature

For related literature, see: Kakanejadifard, Niknam & Zabardasti (2007); Kakanejadifard, Saniei et al. (2007); Kakanejadifard & Niknam (2006); For general background, see: Jones et al. (1961); Schrauzer & Kohnle (1964); Yari et al. (2006); Hashemi et al. (2006); Ghiasvand et al. (2004, 2005); Kakanejadifard, Niknam, Ranjbar et al. (2007); Gok & Kantekin (1997).

Experimental

Crystal data

• C₈H₈N₄O₂

• M_r = 192.18

• Orthorhombic, F d d d

• a = 9.831 (2) Å

• b = 13.609 (3) Å

• c = 24.344 (5) Å

• V = 3256.9 (11) ų

• Z = 16

• Mo Kα radiation

• μ = 0.12 mm⁻¹

• T = 120 (2) K

• 0.4 × 0.2 × 0.2 mm

Data collection

• Bruker SMART 1000 CCD area-detector diffractometer

• Absorption correction: none

• 7925 measured reflections

• 983 independent reflections

• 708 reflections with I > 2σ(I)

• R_int = 0.065

Refinement

• R[F² > 2σ(F²)] = 0.060

• wR(F²) = 0.118

• S = 1.01

• 983 reflections

• 67 parameters

• 1 restraint

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

• Δρ_max = 0.43 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1^i	0.852 (13)	1.971 (10)	2.763 (2)	154
N2—H2A⋯O1	0.86	2.25	2.566 (3)	102
Symmetry code: (i) -x+1, -y, -z+1.

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

Recently, we have reported the syntheses and chemical behaviours of some vic-dioximes. In our investigations, the reactions of amines with dichloro- glyoxime or cyanogendi-N-oxide resulted in various symmetrically substituted diaminoglyoxime derivatives, in which some of them were quite suitable to act, as donor species, towards some transition metal ions (Kakanejadifard, Niknam & Zabardasti, 2007; Kakanejadifard, Saniei et al., 2007; Kakanejadifard & Niknam, 2006). Some oximes are widely used for various purposes in organic, inorganic, bioinorganic, pigment, analytical, dyes and medical chemistry (Jones et al., 1961; Schrauzer & Kohnle, 1964;Yari et al., 2006; Hashemi et al., 2006; Ghiasvand et al., 2004, 2005; Kakanejadifard, Niknam, Ranjbar et al., 2007). vic-Dioximes, containing mildly acidic hydroxyl groups and slightly basic nitrogen atoms, are amphoteric and their transition metal complexes have been widely investigated as analytical reagents (Gok & Kantekin, 1997). We report herein the synthesis and crystal structure of the title compound.

The asymmetric unit of the title compound contains one-half molecule (Fig. 1). The intramolecular N-H···O hydrogen bond (Table 1) results in the formation of a five-membered ring: (O1/N1/N2/C1/H2A), having envelope conformation, with H2A atom displaced by -0.132 Å from the plane of the other ring atoms.

In the crystal structure, intermolecular O-H···N hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Related literature

For related literature, see: Kakanejadifard, Niknam & Zabardasti (2007); Kakanejadifard, Saniei et al. (2007); Kakanejadifard & Niknam (2006); For general background, see: Jones et al. (1961); Schrauzer & Kohnle (1964); Yari et al. (2006); Hashemi et al. (2006); Ghiasvand et al. (2004, 2005); Kakanejadifard, Niknam, Ranjbar et al. (2007); Gok & Kantekin (1997).

S2. Experimental

For the preparation of the title compound, a solution of Na₂CO₃ (0.2 g, 1.9 mmol) in MeCN (30 ml) was added to a magnetically stirred solution of dicholoroglyoxime (1.57 g, 10 mmol) in MeCN (20 ml) and a solution of 1,2-phenylendiamine (1.08 g, 10 mmol) at 278 K. After 2 h stirring at room temperature, the mixture was filtered and the brown precipitate was washed with cold MeCN. It was recrystallized from EtOH (70% aq) in one week (yield; 93.0%, m.p. 512 K).

S3. Refinement

H1 atom (for OH) was located in difference syntheses and refined [O-H = 0.852 (13) Å, U_iso(H) = 0.039 Ų]. The remaining H atoms were positioned geometrically, with N-H = 0.86 Å (for NH) and C-H = 0.93 Å for aromatic H, and constrained to ride on their parent atoms with U_iso(H) = 1.2U_eq(C,N).

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART (Bruker, 1998); data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (a) 5/4 - x, 1/4 - y, z].
	Fig. 2. A packing diagram of the title molecule. Hydrogen bonds are shown as dashed lines.

(2Z,3Z)-Quinoxaline-2,3(1H,4H)-dione dioxime

Crystal data

C8H8N4O2	F(000) = 1600
Mr = 192.18	Dx = 1.568 Mg m^−3
Orthorhombic, Fddd	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -F 2uv 2vw	Cell parameters from 744 reflections
a = 9.831 (2) Å	θ = 3–30°
b = 13.609 (3) Å	µ = 0.12 mm^−1
c = 24.344 (5) Å	T = 120 K
V = 3256.9 (11) Å^3	Prism, light-brown
Z = 16	0.4 × 0.2 × 0.2 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	708 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.065
Graphite monochromator	θmax = 28.0°, θmin = 2.7°
ϕ and ω scans	h = −12→12
7925 measured reflections	k = −17→17
983 independent reflections	l = −32→31

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)] = 0.060	Hydrogen site location: difference Fourier map
wR(F^2) = 0.118	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ^2(Fo^2) + (0.005P)^2 + 25P] where P = (Fo^2 + 2Fc^2)/3
983 reflections	(Δ/σ)max < 0.001
67 parameters	Δρmax = 0.43 e Å^−3
1 restraint	Δρmin = −0.25 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 > 2sigma(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	0.47468 (17)	−0.04564 (12)	0.43944 (6)	0.0324 (4)
H1	0.454 (3)	−0.0611 (18)	0.4723 (4)	0.039*
N1	0.54273 (19)	0.04548 (13)	0.44726 (7)	0.0261 (4)
N2	0.5691 (2)	0.03307 (14)	0.35156 (7)	0.0308 (5)
H2A	0.5385	−0.0261	0.3513	0.037*
C1	0.5867 (2)	0.07818 (15)	0.40084 (8)	0.0242 (4)
C2	0.5981 (2)	0.07776 (16)	0.30119 (8)	0.0268 (5)
C3	0.5745 (2)	0.03025 (19)	0.25164 (9)	0.0358 (6)
H3A	0.5413	−0.0337	0.2514	0.043*
C4	0.6000 (3)	0.0776 (2)	0.20291 (9)	0.0412 (6)
H4A	0.5835	0.0457	0.1698	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0423 (10)	0.0304 (8)	0.0244 (7)	−0.0098 (7)	0.0009 (7)	0.0025 (7)
N1	0.0314 (9)	0.0243 (9)	0.0226 (8)	−0.0053 (8)	0.0002 (7)	0.0004 (7)
N2	0.0447 (11)	0.0279 (9)	0.0198 (8)	−0.0126 (8)	0.0022 (8)	−0.0015 (7)
C1	0.0282 (11)	0.0261 (10)	0.0184 (9)	−0.0014 (9)	−0.0009 (8)	−0.0002 (8)
C2	0.0282 (11)	0.0334 (11)	0.0187 (9)	−0.0055 (9)	0.0016 (8)	−0.0002 (8)
C3	0.0422 (13)	0.0422 (13)	0.0230 (10)	−0.0154 (11)	0.0041 (10)	−0.0059 (10)
C4	0.0440 (14)	0.0596 (17)	0.0199 (10)	−0.0188 (13)	0.0004 (10)	−0.0054 (10)

Geometric parameters (Å, º)

O1—H1	0.852 (13)	C2—C2^i	1.390 (4)
N1—C1	1.289 (3)	C2—C3	1.388 (3)
N1—O1	1.422 (2)	C3—C4	1.373 (3)
N2—C1	1.359 (2)	C3—H3A	0.9300
N2—C2	1.398 (3)	C4—C4^i	1.380 (5)
N2—H2A	0.8600	C4—H4A	0.9300
C1—C1^i	1.481 (4)
N1—O1—H1	101.8 (17)	C3—C2—N2	121.7 (2)
C1—N1—O1	109.96 (16)	C2^i—C2—N2	118.68 (11)
C1—N2—C2	123.50 (18)	C4—C3—C2	120.1 (2)
C1—N2—H2A	118.3	C4—C3—H3A	120.0
C2—N2—H2A	118.3	C2—C3—H3A	120.0
N1—C1—N2	125.13 (19)	C3—C4—C4^i	120.25 (14)
N1—C1—C1^i	117.89 (12)	C3—C4—H4A	119.9
N2—C1—C1^i	116.98 (12)	C4^i—C4—H4A	119.9
C3—C2—C2^i	119.62 (13)
C1—N2—C2—C3	−177.8 (2)	C2—N2—C1—C1^i	−11.4 (4)
C1—N2—C2—C2^i	2.2 (4)	C2^i—C2—C3—C4	−2.1 (4)
O1—N1—C1—N2	0.8 (3)	N2—C2—C3—C4	177.9 (2)
O1—N1—C1—C1^i	−178.7 (2)	C2—C3—C4—C4^i	0.4 (5)
C2—N2—C1—N1	169.1 (2)

Symmetry code: (i) −x+5/4, −y+1/4, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1^ii	0.85 (1)	1.97 (1)	2.763 (2)	154
N2—H2A···O1	0.86	2.25	2.566 (3)	102

Symmetry code: (ii) −x+1, −y, −z+1.