organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

N,N′-Bis[(E)-quinoxalin-2-ylmethyl­­idene]­ethane-1,2-di­amine

aDepartment of Applied Chemistry, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
*Correspondence e-mail: yusuff@cusat.ac.in

(Received 16 December 2008; accepted 23 January 2009; online 31 January 2009)

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.

Related literature

For the synthesis of the Schiff base, see: Zolezzi et al. (1999[Zolezzi, S., Decinti, A. & Spodine, E. (1999). Polyhedron, 18, 897-904.]). For the properties of Schiff base ligands, see: Gupta & Sutar (2008[Gupta, K. C. & Sutar, A. K. (2008). Coord. Chem. Rev. 252, 1420-1450.]); Harmenberg et al. (1991[Harmenberg, J., Akesson-Johansson, A., Graslund, A., Malmfors, T., Bergman, J., Wahren, B., Akerfeldt, S., Lundblad, L. & Cox, S. (1991). Antiviral Res. 15, 193-204.]); Mayadevi et al. (2003[Mayadevi, S., Prasad, P. G. & Yusuff, K. K. M. (2003). Synth. React. Inorg. Met. Org. Chem. 33, 481-496.]); Miller et al. (1999[Miller, J. K., Baag, J. H. & Abu-Omar, M. M. (1999). Inorg. Chem. 38, 4510-4514.]); Naylor et al. (1993[Naylor, M. A., Stephen, M. A., Nolan, J., Sutton, B., Tocher, J. H., Fielden, E. M., Adams, G. E. & Strafford, I. J. (1993). Anticancer Drug. Des. 8, 439-461.]); Sreekala & Yusuff (1994[Sreekala, R. & Yusuff, K. K. M. (1994). Synth. React. Inorg. Met. Org. Chem. 24, 1773-1788.]); Xavier et al. (2004[Xavier, K. O., Chacko, J. & Yusuff, K. K. M. (2004). Appl. Catal. A Gen. 258, 251-259.]); Yusuff & Sreekala (1991[Yusuff, K. K. M. & Sreekala, R. (1991). Synth. React. Inorg. Met. Org. Chem. 21, 553-568.]). For related structures, see: Habibi et al. (2006[Habibi, M. H., Montazerozohori, M., Lalegani, A., Harrington, R. W. & Clegg, W. (2006). J. Fluorine Chem. 127, 769-773.]); Taylor & Kennard (1982[Taylor, R. & Kennard, O. (1982). J. Am. Chem. Soc. 104, 5063-5070.]).

[Scheme 1]

Experimental

Crystal data
  • C20H16N6

  • Mr = 340.39

  • Triclinic, [P \overline 1]

  • a = 6.888 (2) Å

  • b = 7.381 (3) Å

  • c = 9.638 (4) Å

  • α = 101.674 (6)°

  • β = 96.233 (6)°

  • γ = 116.046 (5)°

  • V = 420.1 (3) Å3

  • Z = 1

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 298 (2) K

  • 0.40 × 0.24 × 0.18 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2001[Sheldrick, G. M. (2001). SADABS. University of Göttingen, Germany.]) Tmin = 0.967, Tmax = 0.995

  • 3956 measured reflections

  • 1465 independent reflections

  • 1239 reflections with I > 2σ(I)

  • Rint = 0.025

Refinement
  • R[F2 > 2σ(F2)] = 0.071

  • wR(F2) = 0.164

  • S = 1.27

  • 1465 reflections

  • 118 parameters

  • H-atom parameters constrained

  • Δρmax = 0.13 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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.

Data collection: SMART (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and/or ORTEP-3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]).

Supporting information


Comment top

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.

Related literature top

For the synthesis of the Schiff base, see: Zolezzi et al. (1999). For the properties of Schiff base ligands, see: Gupta & Sutar (2008); Harmenberg et al. (1991); Mayadevi et al. (2003); Miller et al. (1999); Naylor et al. (1993); Sreekala & Yusuff (1994); Xavier et al. (2004); Yusuff & Sreekala (1991). For related structures, see: Habibi et al. (2006); Taylor & Kennard (1982).

Experimental top

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.

Refinement top

H atoms were positioned geometrically with, C—H = 0.93 A° and refined in riding mode with Uiso (H) = 1.2Ueq(C).

Computing details top

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).

Figures top
[Figure 1] 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] Fig. 2. Unit cell packing diagram of N,N'-bis[(E)-quinoxalin-2-ylmethylidene]ethane-1,2-diamine.
[Figure 3] Fig. 3. Pairs of (C–)H···N interactions lead to a layer structure along the a axis.
N,N'-Bis[(E)-quinoxalin-2-ylmethylidene]ethane-1,2-diamine top
Crystal data top
C20H16N6Z = 1
Mr = 340.39F(000) = 178
Triclinic, P1Dx = 1.345 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.888 (2) ÅCell parameters from 1465 reflections
b = 7.381 (3) Åθ = 2.3–25.0°
c = 9.638 (4) ŵ = 0.09 mm1
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
Data collection top
Bruker SMART CCD area-detector
diffractometer
1465 independent reflections
Radiation source: fine-focus sealed tube1239 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
ϕ and ω scansθmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2001)
h = 88
Tmin = 0.967, Tmax = 0.995k = 88
3956 measured reflectionsl = 1111
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.071Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.164H-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 parametersΔρmax = 0.13 e Å3
0 restraintsΔρmin = 0.21 e Å3
Crystal data top
C20H16N6γ = 116.046 (5)°
Mr = 340.39V = 420.1 (3) Å3
Triclinic, P1Z = 1
a = 6.888 (2) ÅMo Kα radiation
b = 7.381 (3) ŵ = 0.09 mm1
c = 9.638 (4) ÅT = 298 K
α = 101.674 (6)°0.40 × 0.24 × 0.18 mm
β = 96.233 (6)°
Data collection top
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 = 0.995Rint = 0.025
3956 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0710 restraints
wR(F2) = 0.164H-atom parameters constrained
S = 1.27Δρmax = 0.13 e Å3
1465 reflectionsΔρmin = 0.21 e Å3
118 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
N10.4604 (3)0.2446 (3)0.5782 (2)0.0439 (6)
N20.0673 (3)0.2571 (3)0.4735 (2)0.0405 (6)
N30.0679 (3)0.3587 (3)0.8476 (2)0.0425 (6)
C10.5203 (4)0.1943 (4)0.3355 (3)0.0482 (7)
H10.64880.18810.36820.058*
C20.4561 (5)0.1772 (4)0.1921 (3)0.0518 (8)
H20.54250.16080.12800.062*
C30.2624 (5)0.1841 (4)0.1406 (3)0.0522 (8)
H30.22160.17350.04290.063*
C40.1338 (4)0.2062 (4)0.2329 (3)0.0473 (7)
H40.00320.20700.19750.057*
C50.1963 (4)0.2279 (4)0.3820 (3)0.0374 (6)
C60.3918 (4)0.2210 (4)0.4334 (3)0.0381 (6)
C70.3349 (4)0.2733 (4)0.6617 (3)0.0429 (7)
H70.37640.28970.76040.051*
C80.1382 (4)0.2813 (4)0.6116 (3)0.0371 (6)
C90.0064 (4)0.3217 (4)0.7124 (3)0.0419 (6)
H90.12510.31980.67540.050*
C100.0707 (4)0.3998 (4)0.9395 (3)0.0438 (7)
H10A0.14150.28350.98040.053*
H10B0.18570.41330.88200.053*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0419 (12)0.0551 (14)0.0405 (12)0.0272 (11)0.0095 (10)0.0150 (10)
N20.0409 (12)0.0465 (13)0.0350 (12)0.0231 (11)0.0064 (9)0.0084 (10)
N30.0463 (13)0.0504 (13)0.0342 (12)0.0257 (11)0.0108 (9)0.0113 (10)
C10.0440 (15)0.0514 (17)0.0495 (16)0.0233 (14)0.0136 (13)0.0113 (13)
C20.0565 (18)0.0512 (17)0.0433 (16)0.0210 (14)0.0221 (13)0.0093 (13)
C30.0596 (18)0.0568 (18)0.0332 (14)0.0228 (15)0.0095 (13)0.0101 (13)
C40.0497 (16)0.0554 (18)0.0345 (14)0.0243 (14)0.0039 (12)0.0122 (12)
C50.0375 (14)0.0327 (13)0.0385 (14)0.0138 (11)0.0077 (11)0.0098 (11)
C60.0380 (13)0.0377 (14)0.0372 (13)0.0173 (12)0.0074 (11)0.0096 (11)
C70.0448 (15)0.0524 (16)0.0313 (13)0.0233 (13)0.0052 (11)0.0127 (12)
C80.0368 (13)0.0367 (14)0.0357 (14)0.0173 (11)0.0061 (11)0.0071 (11)
C90.0414 (15)0.0457 (16)0.0406 (15)0.0229 (13)0.0076 (12)0.0113 (12)
C100.0443 (15)0.0528 (17)0.0368 (14)0.0235 (13)0.0139 (11)0.0139 (12)
Geometric parameters (Å, º) top
N1—C71.298 (3)C3—H30.9300
N1—C61.373 (3)C4—C51.410 (3)
N2—C81.315 (3)C4—H40.9300
N2—C51.369 (3)C5—C61.409 (3)
N3—C91.260 (3)C7—C81.418 (3)
N3—C101.455 (3)C7—H70.9300
C1—C21.367 (4)C8—C91.472 (3)
C1—C61.404 (3)C9—H90.9300
C1—H10.9300C10—C10i1.512 (5)
C2—C31.398 (4)C10—H10A0.9700
C2—H20.9300C10—H10B0.9700
C3—C41.357 (4)
C7—N1—C6115.8 (2)N1—C6—C1119.7 (2)
C8—N2—C5116.2 (2)N1—C6—C5120.9 (2)
C9—N3—C10117.9 (2)C1—C6—C5119.4 (2)
C2—C1—C6119.9 (3)N1—C7—C8124.0 (2)
C2—C1—H1120.1N1—C7—H7118.0
C6—C1—H1120.1C8—C7—H7118.0
C1—C2—C3121.0 (3)N2—C8—C7121.6 (2)
C1—C2—H2119.5N2—C8—C9116.9 (2)
C3—C2—H2119.5C7—C8—C9121.5 (2)
C4—C3—C2120.1 (3)N3—C9—C8121.5 (2)
C4—C3—H3120.0N3—C9—H9119.3
C2—C3—H3120.0C8—C9—H9119.3
C3—C4—C5120.7 (3)N3—C10—C10109.5 (3)
C3—C4—H4119.7N3—C10—H10A109.8
C5—C4—H4119.7C10—C10—H10A109.8
N2—C5—C6121.6 (2)N3—C10—H10B109.8
N2—C5—C4119.4 (2)C10—C10—H10B109.8
C6—C5—C4119.0 (2)H10A—C10—H10B108.2
Symmetry code: (i) x, y+1, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···N2ii0.932.733.647 (4)168
C9—H9···N1iii0.932.673.593 (3)169
Symmetry codes: (ii) x+1, y, z; (iii) x1, y, z.

Experimental details

Crystal data
Chemical formulaC20H16N6
Mr340.39
Crystal system, space groupTriclinic, P1
Temperature (K)298
a, b, c (Å)6.888 (2), 7.381 (3), 9.638 (4)
α, β, γ (°)101.674 (6), 96.233 (6), 116.046 (5)
V3)420.1 (3)
Z1
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.40 × 0.24 × 0.18
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2001)
Tmin, Tmax0.967, 0.995
No. of measured, independent and
observed [I > 2σ(I)] reflections
3956, 1465, 1239
Rint0.025
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.071, 0.164, 1.27
No. of reflections1465
No. of parameters118
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.13, 0.21

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXTL (Farrugia, 1997), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···N2i0.932.733.647 (4)168
C9—H9···N1ii0.932.673.593 (3)169
Symmetry codes: (i) x+1, y, z; (ii) x1, y, z.
 

Acknowledgements

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.

References

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