Acta Cryst. (2009). E65, o435 [ doi:10.1107/S1600536809003006 ]
In the molecule of the title compound, C20H16N6, the central C-C bond lies on a crystallographic inversion centre. The quinoxalidine ring is nearly planar, with a maximum deviation of 0.021 (2) Å from the mean plane. The crystal structure is stabilized by intermolecular C-H
N interactions, leading to the formation of a layer-like structure, which extends along the a axis.
A hot solution of ethylenediamine (1 mmol) in methanol (25 ml) was slowly added over a hot solution of quinoxaline-2-carboxaldehyde (2 mmol) in the same solvent (50 ml). The resulting mixture on cooling yielded the crude product. The precipitated diimine was filtered off and washed with cold methanol. Light yellow single crystals of (1) were obtained from a solution of dichloromethane by slow evaporation.
H atoms were positioned geometrically with, C—H = 0.93 A° and refined in riding mode with Uiso (H) = 1.2Ueq(C).
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).
![[Figure 1]](./fj2185fig1thm.gif)
| Fig. 1. An ORTEP-3 (Farrugia, 1997) plot of the (I) compound, with the atomic labelling scheme. The shapes of the ellipsoids correspond to 50% probability contours of atomic displacement. |
![[Figure 2]](./fj2185fig2thm.gif)
| Fig. 2. Unit cell packing diagram of N,N'-bis[(E)-quinoxalin-2-ylmethylidene]ethane-1,2-diamine. |
![[Figure 3]](./fj2185fig3thm.gif)
| Fig. 3. Pairs of (C–)H···N interactions lead to a layer structure along the a axis. |
| C20H16N6 | Z = 1 |
| Mr = 340.39 | F(000) = 178 |
| Triclinic, P1 | Dx = 1.345 Mg m−3 |
| Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
| a = 6.888 (2) Å | Cell parameters from 1465 reflections |
| b = 7.381 (3) Å | θ = 2.3–25.0° |
| c = 9.638 (4) Å | µ = 0.09 mm−1 |
| α = 101.674 (6)° | T = 298 K |
| β = 96.233 (6)° | Plate, yellow |
| γ = 116.046 (5)° | 0.40 × 0.24 × 0.18 mm |
| V = 420.1 (3) Å3 |
| Bruker SMART CCD area-detector diffractometer | 1465 independent reflections |
| Radiation source: fine-focus sealed tube | 1239 reflections with I > 2σ(I) |
| graphite | Rint = 0.025 |
| φ and ω scans | θmax = 25.0°, θmin = 2.2° |
| Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | h = −8→8 |
| Tmin = 0.967, Tmax = 0.995 | k = −8→8 |
| 3956 measured reflections | l = −11→11 |
| 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)] = 0.071 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.164 | H-atom parameters constrained |
| S = 1.27 | w = 1/[σ2(Fo2) + (0.0542P)2 + 0.1572P] where P = (Fo2 + 2Fc2)/3 |
| 1465 reflections | (Δ/σ)max < 0.001 |
| 118 parameters | Δρmax = 0.13 e Å−3 |
| 0 restraints | Δρmin = −0.21 e Å−3 |
| C20H16N6 | γ = 116.046 (5)° |
| Mr = 340.39 | V = 420.1 (3) Å3 |
| Triclinic, P1 | Z = 1 |
| a = 6.888 (2) Å | Mo Kα radiation |
| b = 7.381 (3) Å | µ = 0.09 mm−1 |
| c = 9.638 (4) Å | T = 298 K |
| α = 101.674 (6)° | 0.40 × 0.24 × 0.18 mm |
| β = 96.233 (6)° |
| Bruker SMART CCD area-detector diffractometer | 1465 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | 1239 reflections with I > 2σ(I) |
| Tmin = 0.967, Tmax = 0.995 | Rint = 0.025 |
| 3956 measured reflections | θmax = 25.0° |
| R[F2 > 2σ(F2)] = 0.071 | H-atom parameters constrained |
| wR(F2) = 0.164 | Δρmax = 0.13 e Å−3 |
| S = 1.27 | Δρmin = −0.21 e Å−3 |
| 1465 reflections | Absolute structure: ? |
| 118 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
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 | ||
| N1 | 0.4604 (3) | 0.2446 (3) | 0.5782 (2) | 0.0439 (6) | |
| N2 | 0.0673 (3) | 0.2571 (3) | 0.4735 (2) | 0.0405 (6) | |
| N3 | 0.0679 (3) | 0.3587 (3) | 0.8476 (2) | 0.0425 (6) | |
| C1 | 0.5203 (4) | 0.1943 (4) | 0.3355 (3) | 0.0482 (7) | |
| H1 | 0.6488 | 0.1881 | 0.3682 | 0.058* | |
| C2 | 0.4561 (5) | 0.1772 (4) | 0.1921 (3) | 0.0518 (8) | |
| H2 | 0.5425 | 0.1608 | 0.1280 | 0.062* | |
| C3 | 0.2624 (5) | 0.1841 (4) | 0.1406 (3) | 0.0522 (8) | |
| H3 | 0.2216 | 0.1735 | 0.0429 | 0.063* | |
| C4 | 0.1338 (4) | 0.2062 (4) | 0.2329 (3) | 0.0473 (7) | |
| H4 | 0.0032 | 0.2070 | 0.1975 | 0.057* | |
| C5 | 0.1963 (4) | 0.2279 (4) | 0.3820 (3) | 0.0374 (6) | |
| C6 | 0.3918 (4) | 0.2210 (4) | 0.4334 (3) | 0.0381 (6) | |
| C7 | 0.3349 (4) | 0.2733 (4) | 0.6617 (3) | 0.0429 (7) | |
| H7 | 0.3764 | 0.2897 | 0.7604 | 0.051* | |
| C8 | 0.1382 (4) | 0.2813 (4) | 0.6116 (3) | 0.0371 (6) | |
| C9 | 0.0064 (4) | 0.3217 (4) | 0.7124 (3) | 0.0419 (6) | |
| H9 | −0.1251 | 0.3198 | 0.6754 | 0.050* | |
| C10 | −0.0707 (4) | 0.3998 (4) | 0.9395 (3) | 0.0438 (7) | |
| H10A | −0.1415 | 0.2835 | 0.9804 | 0.053* | |
| H10B | −0.1857 | 0.4133 | 0.8820 | 0.053* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| N1 | 0.0419 (12) | 0.0551 (14) | 0.0405 (12) | 0.0272 (11) | 0.0095 (10) | 0.0150 (10) |
| N2 | 0.0409 (12) | 0.0465 (13) | 0.0350 (12) | 0.0231 (11) | 0.0064 (9) | 0.0084 (10) |
| N3 | 0.0463 (13) | 0.0504 (13) | 0.0342 (12) | 0.0257 (11) | 0.0108 (9) | 0.0113 (10) |
| C1 | 0.0440 (15) | 0.0514 (17) | 0.0495 (16) | 0.0233 (14) | 0.0136 (13) | 0.0113 (13) |
| C2 | 0.0565 (18) | 0.0512 (17) | 0.0433 (16) | 0.0210 (14) | 0.0221 (13) | 0.0093 (13) |
| C3 | 0.0596 (18) | 0.0568 (18) | 0.0332 (14) | 0.0228 (15) | 0.0095 (13) | 0.0101 (13) |
| C4 | 0.0497 (16) | 0.0554 (18) | 0.0345 (14) | 0.0243 (14) | 0.0039 (12) | 0.0122 (12) |
| C5 | 0.0375 (14) | 0.0327 (13) | 0.0385 (14) | 0.0138 (11) | 0.0077 (11) | 0.0098 (11) |
| C6 | 0.0380 (13) | 0.0377 (14) | 0.0372 (13) | 0.0173 (12) | 0.0074 (11) | 0.0096 (11) |
| C7 | 0.0448 (15) | 0.0524 (16) | 0.0313 (13) | 0.0233 (13) | 0.0052 (11) | 0.0127 (12) |
| C8 | 0.0368 (13) | 0.0367 (14) | 0.0357 (14) | 0.0173 (11) | 0.0061 (11) | 0.0071 (11) |
| C9 | 0.0414 (15) | 0.0457 (16) | 0.0406 (15) | 0.0229 (13) | 0.0076 (12) | 0.0113 (12) |
| C10 | 0.0443 (15) | 0.0528 (17) | 0.0368 (14) | 0.0235 (13) | 0.0139 (11) | 0.0139 (12) |
| N1—C7 | 1.298 (3) | C3—H3 | 0.9300 |
| N1—C6 | 1.373 (3) | C4—C5 | 1.410 (3) |
| N2—C8 | 1.315 (3) | C4—H4 | 0.9300 |
| N2—C5 | 1.369 (3) | C5—C6 | 1.409 (3) |
| N3—C9 | 1.260 (3) | C7—C8 | 1.418 (3) |
| N3—C10 | 1.455 (3) | C7—H7 | 0.9300 |
| C1—C2 | 1.367 (4) | C8—C9 | 1.472 (3) |
| C1—C6 | 1.404 (3) | C9—H9 | 0.9300 |
| C1—H1 | 0.9300 | C10—C10i | 1.512 (5) |
| C2—C3 | 1.398 (4) | C10—H10A | 0.9700 |
| C2—H2 | 0.9300 | C10—H10B | 0.9700 |
| C3—C4 | 1.357 (4) | ||
| C7—N1—C6 | 115.8 (2) | N1—C6—C1 | 119.7 (2) |
| C8—N2—C5 | 116.2 (2) | N1—C6—C5 | 120.9 (2) |
| C9—N3—C10 | 117.9 (2) | C1—C6—C5 | 119.4 (2) |
| C2—C1—C6 | 119.9 (3) | N1—C7—C8 | 124.0 (2) |
| C2—C1—H1 | 120.1 | N1—C7—H7 | 118.0 |
| C6—C1—H1 | 120.1 | C8—C7—H7 | 118.0 |
| C1—C2—C3 | 121.0 (3) | N2—C8—C7 | 121.6 (2) |
| C1—C2—H2 | 119.5 | N2—C8—C9 | 116.9 (2) |
| C3—C2—H2 | 119.5 | C7—C8—C9 | 121.5 (2) |
| C4—C3—C2 | 120.1 (3) | N3—C9—C8 | 121.5 (2) |
| C4—C3—H3 | 120.0 | N3—C9—H9 | 119.3 |
| C2—C3—H3 | 120.0 | C8—C9—H9 | 119.3 |
| C3—C4—C5 | 120.7 (3) | N3—C10—C10 | 109.5 (3) |
| C3—C4—H4 | 119.7 | N3—C10—H10A | 109.8 |
| C5—C4—H4 | 119.7 | C10—C10—H10A | 109.8 |
| N2—C5—C6 | 121.6 (2) | N3—C10—H10B | 109.8 |
| N2—C5—C4 | 119.4 (2) | C10—C10—H10B | 109.8 |
| C6—C5—C4 | 119.0 (2) | H10A—C10—H10B | 108.2 |
| Symmetry codes: (i) −x, −y+1, −z+2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| C1—H1···N2ii | 0.93 | 2.73 | 3.647 (4) | 168 |
| C9—H9···N1iii | 0.93 | 2.67 | 3.593 (3) | 169 |
| Symmetry codes: (ii) x+1, y, z; (iii) x−1, y, z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| C1—H1···N2i | 0.93 | 2.73 | 3.647 (4) | 168 |
| C9—H9···N1ii | 0.93 | 2.67 | 3.593 (3) | 169 |
| Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z. |
The authors thank Professor M. V. Rajasekharan, School of Chemistry, University of Hyderabad, for kind help and useful discussions. The X-ray data were collected on the diffractometer facilities at the University of Hyderabad provided by the Department of Science and Technology. DV gratefully acknowledges financial support from the Council of Scientific and Industrial Research (CSIR), India. MS thanks KSCSTE, Trivandrum, Kerala, for financial assistance KSCSTE, Trivandrum, Kerala.
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Schiff bases derived from aldehydes and diamines constitute one of the most relevant synthetic ligand systems. They find application in a broad range of transition metal catalyzed reactions including lactide polymerization, epoxidation of olefins, hydroxylation and asymmetric ring opening of epoxides (Gupta & Sutar, 2008). Many drug candidates bearing quinoxaline core structures are in clinical trials in antiviral (Harmenberg et al., 1991), anticancer and central nervous system therapeutic areas (Naylor et al., 1993). Catalytic and antibacterial activities have been observed for the Schiff base complexes derived from Quinoxaline-2-carboxaldehyde (Yusuff & Sreekala, 1991; Sreekala & Yusuff, 1994; Mayadevi et al., 2003). Ethylenediamine groups appear to be of importance for various transition metal catalysis (Miller et al., 1999; Xavier et al., 2004). We have recently prepared the title compound (1), and report here its structure.
The single-crystal X-ray structure determination of (1) was carried out at 298 (2) K. The structure analysis showed that the compound to form in triclinic space group P-1 with a =6.888 (2) A°, b=7.381 (3) A°, c=9.638 (4) A° and α = 101.674 (6)°, β = 96.233 (6)°, γ = 116.046 (5)° with z=1. A perspective drawing is depicted in figure 1 with the atomic numbering scheme. The C10—N3—C9, N3—C9—C8 angles are 117.9 (2)° and 121.5 (2)° respectively. The N3—C10 and N3—C9 bond lengths are 1.455 (3) A° and 1.260 (3) A° respectively. In this compound (1), the short (C–)H···N contacts are responsible for the stability of layer structure (figure 3) which extends along the a axis (Taylor & Kennard, 1982). The (C–)H···N distances and C—H—N angles are given in table 1.