Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807025792/hb2434sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807025792/hb2434Isup2.hkl |
CCDC reference: 654864
Key indicators
- Single-crystal X-ray study
- T = 130 K
- Mean (C-C) = 0.004 Å
- R factor = 0.050
- wR factor = 0.109
- Data-to-parameter ratio = 11.3
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT245_ALERT_2_C U(iso) H3O' Smaller than U(eq) O3 by ... 0.02 AngSq PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.46 PLAT355_ALERT_3_C Long O-H Bond (0.82A) O1 - H1O ... 1.01 Ang. PLAT480_ALERT_4_C Long H...A H-Bond Reported H2A .. O2 .. 2.63 Ang. PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........ 1
Alert level G PLAT793_ALERT_1_G Check the Absolute Configuration of C2 = ... S
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 5 ALERT level C = Check and explain 1 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 1 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
For the crystal structure of dihydroxyacetic acid, see: Lis (1983 or???1982). For crystal structures of quinoxaline complexes with carboxylic acids, see: Czapik & Gdaniec (2007); Jankowski et al. (2007); Olenik et al. (2003).
The title compound was obtained by dissolving equimolar amounts of quinoxaline (Aldrich) and dihydroxyacetic acid (glyoxalic acid monohydrate, Aldrich) in acetone and slow evaporation of the solution to yield colourles needles of (I).
All the H atoms were located in difference maps. The C-bonded H atoms were placed at calculated positions, with C—H = 0.93 Å, and were refined as riding with Uiso(H) = 1.2Ueq(C). The atoms H1O and H4O from the carboxy group and one of the hydroxy groups were freely refined. The H atom bonded to O3 was disordered over two positions. The half-occupancy was assumed for each position and the H3O and H3O' were refined as riding on O3 (O—H = 0.85 Å) with the isotropic displacement parameters refined.
In the chemical literature dihydroxyacetic acid is often referred to as glyoxalic acid monohydrate. The latter name is also used by the chemical companies selling this compound. Already some 25 years ago Lis (1983) published the crystal structure of 'glyoxalic acid monohydrate' and clearly showed that the compound is not a monohydrate but a product of the reaction of glyoxalic acid with water, namely dihydroxyacetic acid. Interestingly, this simple and small molecule, which can act as a triple donor in hydrogen bonding, has not been applied as reagent in supramolecular chemistry up till now.
In course of our studies on molecular complexes of azaaromatic heterocycles we cocrystallized quinoxaline with dihydroxyacetic acid obtaining the title molecular complex, (I), of 1:1 stoichiometry. It is evident from the crystal structure of the complex that the acid cocrystallizes with the aromatic base in the form of dihydroxyacetic acid (Fig. 1).
Crystal packing of (I) is shown in Fig. 2. The dihydroxyacetic acid molecules interact with the two N atoms of the base via the carboxylic group and one hydroxy group forming a chain parallel to [110]. The carboxylic group is approximately coplanar with the aromatic base and is linked to the quinoxaline molecule by N—H···O and C—H···O interactions generating the cyclic R22(7) motif (Fig. 2, Table 1). The supramolecular chains are further assembled into a three-dimensional network via ···O—H···O—H··· hydrogen bonds joining the hydroxy groups of the acid. The hydrogen atom involved in this interaction is disordered over two positions, corresponding to two different directions of the ···O—H···O—H··· hydrogen-bonding chain (Fig. 3). The three-dimensional network of molecules is additionaly stabilized by weaker C—H···O interactions (Table 1). The quinoxaline molecules are arranged into infinite columns by π–π stacking interactions, with the interplanar distance of 3.427 (7) Å between the best planes of the neighbouring molecules.
For the crystal structure of dihydroxyacetic acid, see: Lis (1983 or???1982). For crystal structures of quinoxaline complexes with carboxylic acids, see: Czapik & Gdaniec (2007); Jankowski et al. (2007); Olenik et al. (2003).
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989) and Mercury (Version 1.4; Macrae et al., 2006); software used to prepare material for publication: SHELXL97.
C8H6N2·C2H4O4 | Z = 2 |
Mr = 222.20 | F(000) = 232 |
Triclinic, P1 | Dx = 1.478 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 4.0384 (9) Å | Cell parameters from 1787 reflections |
b = 10.406 (4) Å | θ = 4–25° |
c = 12.052 (3) Å | µ = 0.12 mm−1 |
α = 88.83 (2)° | T = 130 K |
β = 83.981 (18)° | Needle, colourless |
γ = 82.50 (2)° | 0.50 × 0.15 × 0.07 mm |
V = 499.4 (3) Å3 |
Kuma KM-4-CCD κ-geometry diffractometer | 1482 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.014 |
Graphite monochromator | θmax = 25.0°, θmin = 4.3° |
ω scans | h = −4→4 |
4271 measured reflections | k = −12→12 |
1760 independent reflections | l = −14→14 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.050 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.109 | w = 1/[σ2(Fo2) + (0.0135P)2 + 0.6727P] where P = (Fo2 + 2Fc2)/3 |
S = 1.23 | (Δ/σ)max < 0.001 |
1760 reflections | Δρmax = 0.22 e Å−3 |
156 parameters | Δρmin = −0.18 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.022 (3) |
C8H6N2·C2H4O4 | γ = 82.50 (2)° |
Mr = 222.20 | V = 499.4 (3) Å3 |
Triclinic, P1 | Z = 2 |
a = 4.0384 (9) Å | Mo Kα radiation |
b = 10.406 (4) Å | µ = 0.12 mm−1 |
c = 12.052 (3) Å | T = 130 K |
α = 88.83 (2)° | 0.50 × 0.15 × 0.07 mm |
β = 83.981 (18)° |
Kuma KM-4-CCD κ-geometry diffractometer | 1482 reflections with I > 2σ(I) |
4271 measured reflections | Rint = 0.014 |
1760 independent reflections |
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.109 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.23 | Δρmax = 0.22 e Å−3 |
1760 reflections | Δρmin = −0.18 e Å−3 |
156 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1A | 0.6041 (6) | 0.4249 (2) | 0.74215 (17) | 0.0230 (5) | |
C2A | 0.8100 (7) | 0.3827 (3) | 0.6554 (2) | 0.0259 (6) | |
H2A | 0.8333 | 0.4366 | 0.5934 | 0.031* | |
C3A | 0.9982 (7) | 0.2579 (2) | 0.6529 (2) | 0.0253 (6) | |
H3A | 1.1405 | 0.2322 | 0.5893 | 0.030* | |
N4A | 0.9772 (5) | 0.17718 (19) | 0.73826 (17) | 0.0219 (5) | |
C5A | 0.7358 (7) | 0.1375 (2) | 0.9245 (2) | 0.0239 (6) | |
H5A | 0.8556 | 0.0548 | 0.9233 | 0.029* | |
C6A | 0.5324 (7) | 0.1800 (3) | 1.0178 (2) | 0.0268 (6) | |
H6A | 0.5193 | 0.1266 | 1.0806 | 0.032* | |
C7A | 0.3426 (7) | 0.3036 (3) | 1.0201 (2) | 0.0267 (6) | |
H7A | 0.2033 | 0.3310 | 1.0839 | 0.032* | |
C8A | 0.3625 (6) | 0.3834 (2) | 0.9289 (2) | 0.0231 (6) | |
H8A | 0.2343 | 0.4645 | 0.9304 | 0.028* | |
C9A | 0.5765 (6) | 0.3433 (2) | 0.83244 (19) | 0.0191 (5) | |
C10A | 0.7644 (6) | 0.2187 (2) | 0.8300 (2) | 0.0194 (5) | |
C1 | 0.3848 (6) | 0.7312 (2) | 0.6450 (2) | 0.0211 (6) | |
C2 | 0.2222 (7) | 0.8718 (2) | 0.6412 (2) | 0.0243 (6) | |
H2 | −0.0171 | 0.8771 | 0.6677 | 0.029* | |
O1 | 0.2775 (5) | 0.67053 (18) | 0.73625 (15) | 0.0294 (5) | |
H1O | 0.396 (9) | 0.579 (4) | 0.739 (3) | 0.060 (11)* | |
O2 | 0.5905 (5) | 0.68219 (19) | 0.57360 (16) | 0.0386 (6) | |
O3 | 0.2604 (6) | 0.91914 (19) | 0.53107 (16) | 0.0446 (6) | |
H3O | 0.1363 | 0.9770 | 0.4983 | 0.06 (2)* | 0.50 |
H3O' | 0.4008 | 0.9730 | 0.5326 | 0.028 (17)* | 0.50 |
O4 | 0.3842 (5) | 0.94045 (17) | 0.71321 (15) | 0.0249 (4) | |
H4O | 0.242 (9) | 1.017 (4) | 0.727 (3) | 0.057 (11)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1A | 0.0281 (12) | 0.0176 (11) | 0.0232 (11) | −0.0019 (9) | −0.0045 (9) | 0.0032 (9) |
C2A | 0.0336 (16) | 0.0229 (13) | 0.0213 (13) | −0.0051 (11) | −0.0027 (12) | 0.0049 (11) |
C3A | 0.0311 (15) | 0.0231 (13) | 0.0212 (13) | −0.0045 (11) | 0.0005 (11) | −0.0011 (11) |
N4A | 0.0235 (12) | 0.0179 (11) | 0.0235 (11) | 0.0001 (9) | −0.0019 (9) | −0.0020 (9) |
C5A | 0.0255 (15) | 0.0193 (13) | 0.0273 (14) | −0.0015 (11) | −0.0075 (11) | 0.0051 (11) |
C6A | 0.0311 (15) | 0.0282 (14) | 0.0220 (13) | −0.0068 (12) | −0.0043 (11) | 0.0062 (11) |
C7A | 0.0270 (15) | 0.0322 (15) | 0.0213 (13) | −0.0063 (12) | 0.0000 (11) | −0.0019 (11) |
C8A | 0.0225 (14) | 0.0210 (13) | 0.0255 (13) | −0.0017 (11) | −0.0020 (11) | −0.0019 (11) |
C9A | 0.0210 (13) | 0.0175 (12) | 0.0194 (12) | −0.0027 (10) | −0.0051 (10) | 0.0004 (10) |
C10A | 0.0210 (13) | 0.0168 (12) | 0.0213 (13) | −0.0033 (10) | −0.0049 (10) | −0.0006 (10) |
C1 | 0.0241 (14) | 0.0199 (13) | 0.0191 (13) | −0.0033 (11) | −0.0021 (11) | 0.0036 (10) |
C2 | 0.0255 (14) | 0.0206 (13) | 0.0255 (13) | 0.0029 (11) | −0.0052 (11) | 0.0034 (11) |
O1 | 0.0352 (12) | 0.0237 (10) | 0.0248 (10) | 0.0040 (9) | 0.0064 (8) | 0.0087 (8) |
O2 | 0.0498 (14) | 0.0280 (11) | 0.0293 (11) | 0.0101 (10) | 0.0160 (10) | 0.0052 (9) |
O3 | 0.0832 (18) | 0.0238 (11) | 0.0291 (11) | −0.0051 (12) | −0.0214 (11) | 0.0104 (9) |
O4 | 0.0264 (10) | 0.0194 (9) | 0.0272 (10) | 0.0053 (8) | −0.0049 (8) | −0.0019 (8) |
N1A—C2A | 1.311 (3) | C8A—C9A | 1.409 (4) |
N1A—C9A | 1.371 (3) | C8A—H8A | 0.9300 |
C2A—C3A | 1.416 (4) | C9A—C10A | 1.413 (3) |
C2A—H2A | 0.9300 | C1—O2 | 1.203 (3) |
C3A—N4A | 1.318 (3) | C1—O1 | 1.319 (3) |
C3A—H3A | 0.9300 | C1—C2 | 1.526 (3) |
N4A—C10A | 1.368 (3) | C2—O4 | 1.399 (3) |
C5A—C6A | 1.367 (4) | C2—O3 | 1.407 (3) |
C5A—C10A | 1.409 (3) | C2—H2 | 0.9800 |
C5A—H5A | 0.9300 | O1—H1O | 1.01 (4) |
C6A—C7A | 1.408 (4) | O3—H3O | 0.8500 |
C6A—H6A | 0.9300 | O3—H3O' | 0.8500 |
C7A—C8A | 1.367 (4) | O4—H4O | 0.93 (4) |
C7A—H7A | 0.9300 | ||
C2A—N1A—C9A | 117.4 (2) | N1A—C9A—C8A | 120.2 (2) |
N1A—C2A—C3A | 122.3 (2) | N1A—C9A—C10A | 120.3 (2) |
N1A—C2A—H2A | 118.8 | C8A—C9A—C10A | 119.5 (2) |
C3A—C2A—H2A | 118.8 | N4A—C10A—C5A | 119.7 (2) |
N4A—C3A—C2A | 121.8 (2) | N4A—C10A—C9A | 121.0 (2) |
N4A—C3A—H3A | 119.1 | C5A—C10A—C9A | 119.2 (2) |
C2A—C3A—H3A | 119.1 | O2—C1—O1 | 124.1 (2) |
C3A—N4A—C10A | 117.2 (2) | O2—C1—C2 | 123.8 (2) |
C6A—C5A—C10A | 120.1 (2) | O1—C1—C2 | 112.1 (2) |
C6A—C5A—H5A | 119.9 | O4—C2—O3 | 111.8 (2) |
C10A—C5A—H5A | 119.9 | O4—C2—C1 | 106.4 (2) |
C5A—C6A—C7A | 120.8 (2) | O3—C2—C1 | 109.5 (2) |
C5A—C6A—H6A | 119.6 | O4—C2—H2 | 109.7 |
C7A—C6A—H6A | 119.6 | O3—C2—H2 | 109.7 |
C8A—C7A—C6A | 120.2 (2) | C1—C2—H2 | 109.7 |
C8A—C7A—H7A | 119.9 | C1—O1—H1O | 111 (2) |
C6A—C7A—H7A | 119.9 | C2—O3—H3O | 129.8 |
C7A—C8A—C9A | 120.3 (2) | C2—O3—H3O' | 104.2 |
C7A—C8A—H8A | 119.9 | H3O—O3—H3O' | 88.0 |
C9A—C8A—H8A | 119.9 | C2—O4—H4O | 105 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···N1A | 1.01 (4) | 1.71 (4) | 2.722 (3) | 179 (3) |
O3—H3O···O3i | 0.85 | 1.87 | 2.678 (4) | 157 |
O3—H3O′···O3ii | 0.85 | 1.97 | 2.763 (5) | 156 |
O4—H4O···N4Aiii | 0.93 (4) | 1.86 (4) | 2.780 (3) | 173 (3) |
C2A—H2A···O2 | 0.93 | 2.63 | 3.287 (3) | 128 |
C2—H2···O4iv | 0.98 | 2.43 | 3.390 (3) | 166 |
C3A—H3A···O2v | 0.93 | 2.36 | 3.138 (3) | 141 |
Symmetry codes: (i) −x, −y+2, −z+1; (ii) −x+1, −y+2, −z+1; (iii) x−1, y+1, z; (iv) x−1, y, z; (v) −x+2, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C8H6N2·C2H4O4 |
Mr | 222.20 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 130 |
a, b, c (Å) | 4.0384 (9), 10.406 (4), 12.052 (3) |
α, β, γ (°) | 88.83 (2), 83.981 (18), 82.50 (2) |
V (Å3) | 499.4 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.50 × 0.15 × 0.07 |
Data collection | |
Diffractometer | Kuma KM-4-CCD κ-geometry |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4271, 1760, 1482 |
Rint | 0.014 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.050, 0.109, 1.23 |
No. of reflections | 1760 |
No. of parameters | 156 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.22, −0.18 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis CCD, CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), Stereochemical Workstation Operation Manual (Siemens, 1989) and Mercury (Version 1.4; Macrae et al., 2006), SHELXL97.
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O···N1A | 1.01 (4) | 1.71 (4) | 2.722 (3) | 179 (3) |
O3—H3O···O3i | 0.85 | 1.87 | 2.678 (4) | 157 |
O3—H3O'···O3ii | 0.85 | 1.97 | 2.763 (5) | 156 |
O4—H4O···N4Aiii | 0.93 (4) | 1.86 (4) | 2.780 (3) | 173 (3) |
C2A—H2A···O2 | 0.93 | 2.63 | 3.287 (3) | 128 |
C2—H2···O4iv | 0.98 | 2.43 | 3.390 (3) | 166 |
C3A—H3A···O2v | 0.93 | 2.36 | 3.138 (3) | 141 |
Symmetry codes: (i) −x, −y+2, −z+1; (ii) −x+1, −y+2, −z+1; (iii) x−1, y+1, z; (iv) x−1, y, z; (v) −x+2, −y+1, −z+1. |
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In the chemical literature dihydroxyacetic acid is often referred to as glyoxalic acid monohydrate. The latter name is also used by the chemical companies selling this compound. Already some 25 years ago Lis (1983) published the crystal structure of 'glyoxalic acid monohydrate' and clearly showed that the compound is not a monohydrate but a product of the reaction of glyoxalic acid with water, namely dihydroxyacetic acid. Interestingly, this simple and small molecule, which can act as a triple donor in hydrogen bonding, has not been applied as reagent in supramolecular chemistry up till now.
In course of our studies on molecular complexes of azaaromatic heterocycles we cocrystallized quinoxaline with dihydroxyacetic acid obtaining the title molecular complex, (I), of 1:1 stoichiometry. It is evident from the crystal structure of the complex that the acid cocrystallizes with the aromatic base in the form of dihydroxyacetic acid (Fig. 1).
Crystal packing of (I) is shown in Fig. 2. The dihydroxyacetic acid molecules interact with the two N atoms of the base via the carboxylic group and one hydroxy group forming a chain parallel to [110]. The carboxylic group is approximately coplanar with the aromatic base and is linked to the quinoxaline molecule by N—H···O and C—H···O interactions generating the cyclic R22(7) motif (Fig. 2, Table 1). The supramolecular chains are further assembled into a three-dimensional network via ···O—H···O—H··· hydrogen bonds joining the hydroxy groups of the acid. The hydrogen atom involved in this interaction is disordered over two positions, corresponding to two different directions of the ···O—H···O—H··· hydrogen-bonding chain (Fig. 3). The three-dimensional network of molecules is additionaly stabilized by weaker C—H···O interactions (Table 1). The quinoxaline molecules are arranged into infinite columns by π–π stacking interactions, with the interplanar distance of 3.427 (7) Å between the best planes of the neighbouring molecules.