3-Methyl­quinoxaline-2-carb­oxy­lic acid 4-oxide monohydrate

In the crystal structure of the title compound, C₁₀H₈N₂O₃·H₂O, mol­ecules are linked via inter­molecular O—H...O and O—H...N hydrogen bonds into a two-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.098
• wR factor = 0.256
• Data-to-parameter ratio = 10.2

checkCIF/PLATON results

No syntax errors found



Alert level C
RFACR01_ALERT_3_C  The value of the weighted R factor is > 0.25
            Weighted R factor given   0.255
THETM01_ALERT_3_C  The value of sine(theta_max)/wavelength is less than 0.590
            Calculated sin(theta_max)/wavelength =    0.5814
PLAT023_ALERT_3_C Resolution (too) Low [sin(theta)/Lambda < 0.6]..      63.69 Deg.
PLAT084_ALERT_2_C High wR2 Value .................................       0.26
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..          8
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.581         14
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?

Alert level G
PLAT072_ALERT_2_G SHELXL First Parameter in WGHT Unusually Large.       0.12
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          2

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   7 ALERT level C = Check and explain
   3 ALERT level G = General alerts; check

   1 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
   6 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The molecular structure of the title compound is shown in Fig. 1. In the crystal structure, molecules are linked via intermolecular O-H···O hydrogen bonds into a two-dimensional network.

Related literature

For the synthesis of the starting material, see: Robertson & Kasublck (1973). For the synthesis of the title compound, see: Dirlam & McFarland (1977).

S2. Experimental

Following the procedure of Dirlam & McFarland (1977) ethyl-3-methyl-2-quinoxalinecarboxylate-1,4-dioxide (2.0 g, 8 mmol) (Robertson & Kasublck, 1973) was dissolved in 1-propanol (20 ml), trimethyl phosphate (2.0 g, 16 mmol) was added dropwise to the solution. The reaction mixture was heated under reflux for 2.5 h, and evaporated to dryness. The residue was recrystallized from ether-hexane (1:1) to yeild 1.6 g (80%) ethyl 2-methyl-3-quinoxalinecarboxylate-1-oxide. Ethyl 2-methyl-3-quinoxalinecarboxylate-1-oxide (5 g, 22 mmol) was suspended in aqueous 0.5M sodium hydroxide solution (50 mL), and stirred for 2 h. Then used concentrated hydrochloric acid to adjust the PH=2. The white solid was collected and recrystallized from water to give 4.0 g (80%) of the the title compound.

S3. Refinement

All H atoms (except for those bonded to the solvent water) were placed in calculated positions C-H = 0.95-0.98Å; O-H = 0.86Å and refined in a riding-model approximation with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C_methyl,O). The H atoms of the solvent water molecule were located in a difference Fourier and there positions were refined with restraints and with U_iso(H) = 1.5U_eq(O).

The crystals of the title compound were of low quality and the data used has resulted in a crystal structure which has lower than normal precision. The precision of the data however is adequate to describe the nature of the hydrogen bonding.

Computing details

Data collection: RAPID-AUTO (Rigaku, 2001); cell refinement: RAPID-AUTO (Rigaku, 2001); data reduction: RAPID-AUTO (Rigaku, 2001); 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: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, showing the labelling scheme. Displacement ellipsoids are drawn at the 30% probability level for all non-H atoms.
	Fig. 2. Part of the crystal structure of the title compound viewed along the a axis. Hydrogen bonds are shown as dashed lines.

3-Methylquinoxaline-2-carboxylic acid 4-oxide monohydrate

Crystal data

C10H8N2O3·H2O	F(000) = 464
Mr = 222.20	Dx = 1.530 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54186 Å
Hall symbol: -P 2ybc	Cell parameters from 426 reflections
a = 6.0526 (13) Å	θ = 3.1–68.1°
b = 18.068 (4) Å	µ = 1.02 mm^−1
c = 8.9195 (19) Å	T = 173 K
β = 98.520 (15)°	Plate, yellow
V = 964.7 (4) Å^3	0.20 × 0.20 × 0.04 mm
Z = 4

Data collection

Rigaku R-AXIS RAPID IP area-detector diffractometer	1568 independent reflections
Radiation source: fine-focus sealed tube	900 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.077
ω scans at fixed χ = 45°	θmax = 63.7°, θmin = 4.9°
Absorption correction: numerical (ABSCOR; Higashi, 1995)	h = −7→7
Tmin = 0.822, Tmax = 0.960	k = −20→20
6140 measured reflections	l = −10→9

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.098	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.256	w = 1/[σ^2(Fo^2) + (0.1186P)^2 + 0.0706P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
1568 reflections	Δρmax = 0.38 e Å^−3
154 parameters	Δρmin = −0.31 e Å^−3
3 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.009 (2)

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
O1W	0.2035 (6)	0.6094 (2)	0.4980 (5)	0.0458 (12)
O1	0.6172 (6)	0.2378 (2)	0.1107 (4)	0.0546 (12)
O2	0.3088 (6)	0.4949 (2)	0.2089 (5)	0.0614 (13)
O3	0.2260 (7)	0.4704 (2)	0.4389 (4)	0.0532 (12)
H3	0.2018	0.5162	0.4401	0.080*
N1	0.4745 (7)	0.2663 (3)	0.1891 (5)	0.0393 (12)
N2	0.1661 (7)	0.3286 (2)	0.3563 (5)	0.0389 (12)
C1	0.1772 (8)	0.2529 (3)	0.3378 (6)	0.0403 (14)
C2	0.0313 (9)	0.2070 (3)	0.4034 (6)	0.0461 (15)
H2	−0.0732	0.2280	0.4609	0.055*
C3	0.0398 (9)	0.1315 (3)	0.3845 (6)	0.0474 (16)
H3A	−0.0604	0.1004	0.4277	0.057*
C4	0.1961 (9)	0.1006 (3)	0.3014 (6)	0.0490 (16)
H4	0.2012	0.0483	0.2900	0.059*
C5	0.3405 (9)	0.1436 (3)	0.2369 (6)	0.0451 (16)
H5	0.4457	0.1219	0.1810	0.054*
C6	0.3311 (8)	0.2207 (3)	0.2547 (6)	0.0387 (14)
C7	0.4655 (9)	0.3408 (3)	0.2072 (6)	0.0402 (15)
C8	0.3058 (9)	0.3687 (3)	0.2920 (6)	0.0383 (14)
C9	0.6295 (9)	0.3835 (3)	0.1352 (6)	0.0482 (16)
H9B	0.7788	0.3625	0.1647	0.072*
H9C	0.6287	0.4352	0.1684	0.072*
H9A	0.5896	0.3812	0.0247	0.072*
C10	0.2818 (9)	0.4516 (3)	0.3070 (7)	0.0434 (15)
H1WB	0.261 (8)	0.643 (2)	0.450 (6)	0.065*
H1WA	0.080 (5)	0.626 (3)	0.522 (6)	0.065*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1W	0.041 (2)	0.044 (3)	0.056 (3)	−0.003 (2)	0.0210 (19)	−0.003 (2)
O1	0.049 (2)	0.054 (3)	0.065 (3)	0.007 (2)	0.021 (2)	−0.005 (2)
O2	0.081 (3)	0.050 (3)	0.059 (3)	0.009 (2)	0.030 (2)	0.008 (2)
O3	0.065 (3)	0.043 (3)	0.056 (3)	0.004 (2)	0.021 (2)	−0.002 (2)
N1	0.032 (2)	0.052 (3)	0.037 (3)	0.005 (2)	0.016 (2)	−0.004 (2)
N2	0.034 (2)	0.040 (3)	0.045 (3)	0.001 (2)	0.013 (2)	−0.006 (2)
C1	0.031 (3)	0.043 (4)	0.048 (3)	0.004 (3)	0.010 (3)	−0.004 (3)
C2	0.044 (3)	0.051 (4)	0.045 (3)	−0.005 (3)	0.010 (3)	−0.007 (3)
C3	0.045 (4)	0.046 (4)	0.056 (4)	−0.011 (3)	0.021 (3)	−0.008 (3)
C4	0.050 (4)	0.040 (4)	0.060 (4)	0.004 (3)	0.018 (3)	−0.003 (3)
C5	0.037 (3)	0.048 (4)	0.053 (4)	0.006 (3)	0.018 (3)	−0.004 (3)
C6	0.037 (3)	0.044 (4)	0.036 (3)	0.000 (3)	0.012 (3)	−0.002 (3)
C7	0.033 (3)	0.049 (4)	0.040 (3)	0.004 (3)	0.008 (2)	−0.003 (3)
C8	0.034 (3)	0.046 (4)	0.036 (3)	0.004 (3)	0.008 (2)	−0.002 (3)
C9	0.045 (4)	0.047 (4)	0.056 (4)	0.003 (3)	0.016 (3)	−0.002 (3)
C10	0.038 (3)	0.047 (4)	0.048 (4)	0.000 (3)	0.015 (3)	−0.006 (3)

Geometric parameters (Å, º)

O1W—H1WB	0.85 (4)	C2—H2	0.9500
O1W—H1WA	0.86 (4)	C3—C4	1.401 (7)
O1—N1	1.296 (5)	C3—H3A	0.9500
O2—C10	1.202 (6)	C4—C5	1.359 (7)
O3—C10	1.316 (6)	C4—H4	0.9500
O3—H3	0.8400	C5—C6	1.404 (7)
N1—C7	1.357 (7)	C5—H5	0.9500
N1—C6	1.388 (6)	C7—C8	1.406 (7)
N2—C8	1.309 (6)	C7—C9	1.477 (7)
N2—C1	1.380 (6)	C8—C10	1.514 (8)
C1—C6	1.401 (6)	C9—H9B	0.9800
C1—C2	1.401 (7)	C9—H9C	0.9800
C2—C3	1.377 (6)	C9—H9A	0.9800
H1WB—O1W—H1WA	108 (4)	C6—C5—H5	120.6
C10—O3—H3	109.5	N1—C6—C1	118.8 (5)
O1—N1—C7	120.0 (5)	N1—C6—C5	120.3 (5)
O1—N1—C6	120.0 (5)	C1—C6—C5	120.9 (5)
C7—N1—C6	120.1 (4)	N1—C7—C8	117.5 (5)
C8—N2—C1	116.8 (4)	N1—C7—C9	115.2 (5)
N2—C1—C6	121.6 (5)	C8—C7—C9	127.3 (5)
N2—C1—C2	119.4 (5)	N2—C8—C7	125.2 (5)
C6—C1—C2	119.0 (5)	N2—C8—C10	115.6 (5)
C3—C2—C1	119.9 (5)	C7—C8—C10	119.0 (5)
C3—C2—H2	120.1	C7—C9—H9B	109.5
C1—C2—H2	120.1	C7—C9—H9C	109.5
C2—C3—C4	120.0 (5)	H9B—C9—H9C	109.5
C2—C3—H3A	120.0	C7—C9—H9A	109.5
C4—C3—H3A	120.0	H9B—C9—H9A	109.5
C5—C4—C3	121.5 (5)	H9C—C9—H9A	109.5
C5—C4—H4	119.3	O2—C10—O3	124.3 (6)
C3—C4—H4	119.3	O2—C10—C8	123.7 (5)
C4—C5—C6	118.7 (5)	O3—C10—C8	112.0 (5)
C4—C5—H5	120.6
C8—N2—C1—C6	0.2 (7)	C4—C5—C6—C1	0.4 (8)
C8—N2—C1—C2	−179.8 (5)	O1—N1—C7—C8	179.4 (4)
N2—C1—C2—C3	179.4 (4)	C6—N1—C7—C8	−0.7 (7)
C6—C1—C2—C3	−0.6 (8)	O1—N1—C7—C9	−1.3 (7)
C1—C2—C3—C4	0.9 (8)	C6—N1—C7—C9	178.7 (4)
C2—C3—C4—C5	−0.6 (8)	C1—N2—C8—C7	−0.4 (8)
C3—C4—C5—C6	0.0 (8)	C1—N2—C8—C10	176.9 (4)
O1—N1—C6—C1	−179.5 (4)	N1—C7—C8—N2	0.6 (8)
C7—N1—C6—C1	0.6 (7)	C9—C7—C8—N2	−178.7 (5)
O1—N1—C6—C5	0.2 (7)	N1—C7—C8—C10	−176.5 (4)
C7—N1—C6—C5	−179.7 (4)	C9—C7—C8—C10	4.2 (8)
N2—C1—C6—N1	−0.3 (7)	N2—C8—C10—O2	−143.8 (5)
C2—C1—C6—N1	179.6 (5)	C7—C8—C10—O2	33.6 (8)
N2—C1—C6—C5	180.0 (5)	N2—C8—C10—O3	35.6 (6)
C2—C1—C6—C5	−0.1 (8)	C7—C8—C10—O3	−147.0 (5)
C4—C5—C6—N1	−179.4 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WB···O1^i	0.85 (4)	1.97 (2)	2.794 (5)	164 (5)
O1W—H1WA···N2^ii	0.86 (4)	2.14 (2)	2.968 (5)	163 (5)
O3—H3···O1W	0.84	1.76	2.574 (5)	162

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