(E)-2-Acetyl­pyrazine 4-nitro­phenyl­hydrazone

In the title compound, C₁₂H₁₁N₅O₂, the mol­ecule adopts an E configuration, with the benzene and pyrazine rings located on opposite sides of the N=C double bond. The face-to-face separations of 3.413 (14) and 3.430 (8) Å, respectively between parallel benzene rings and between pyrazine rings indicate the existence of π–π stacking between adjacent mol­ecules. The crystal structure also contains N—H...N and C—H...O hydrogen bonding.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.043
• wR factor = 0.150
• Data-to-parameter ratio = 15.8

checkCIF/PLATON results

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Alert level C
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
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S1. Comment

Hydrazone and its derivatives have attracted much attention because of their potential application in biology (Okabe et al., 1993; Hu et al., 2001). As part of an ongoing investigation into anti-cancer compounds (Chen et al., 2007), the title compound has recently been prepared in our laboratory and its crystal structure is presented here.

The molecular structure of the title compound is shown in Fig. 1. The molecule adopts an E-configuration, with the benzene and pyrazine rings located on the opposite positions of the N3=C7 double bond, similar to that found in a related structure, (E)-2-Furyl methyl ketone 2,4-dinitrophenylhydrazone (Shan et al., 2008). The pyrazine plane is twisted with respect to the benzene ring by a smaller dihedral angle of 14.25 (10)°.

The partially overlapped arrangement is observed between parallel benzene rings and between parallel pyrazine rings (Fig. 2), face-to-face separations of 3.413 (14) [for benzene rings] and 3.430 (8) Å [for pyrazine rings] are significantly shorter than van der Waals thickness of the aromatic ring (3.70 Å), and indicate the existence of π-π stacking between the adjacent molecules. Intermolecular N—H···N and weak C—H···O hydrogen bondings are present in the crystal structure (Table 1).

Related literature

For general background, see: Okabe et al. (1993); Hu et al. (2001); Chen et al. (2007). For a related structure, see: Shan et al. (2008).

S2. Experimental

4-Nitrophenylhydrazine (0.31 g, 2 mmol) was dissolved in ethanol (10 ml), then H₂SO₄ solution (98%, 0.5 ml) was added slowly to the ethanol solution with stirring. The solution was heated at about 333 K for several minutes until the solution cleared. An ethanol solution (5 ml) of acetylpyrazine (0.24 g, 2 mmol) was dropped slowly into the above solution with continuous stirring, and the mixture solution was kept at about 333 K for 0.5 h. When the solution had cooled to room temperature, yellow microcrystals appeared. They were separated and washed with cold water three times to get the product 0.40 g. Single crystals of the title compound were obtained by recrystallization from an absolute ethanol solution.

S3. Refinement

Methyl H atoms were placed in calculated positions with C—H = 0.96 Å and torsion angle was refined to fit the electron density, U_iso(H) = 1.5U_eq(C). Imino H atom was located in a difference Fourier map and refined as riding in its as-found relative position, U_iso(H) = 1.2U_eq(N). Aromatic H atoms were placed in calculated positions with C—H = 0.93 and refined in riding mode with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku, 2002); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of (I) with 30% probability displacement ellipsoids (arbitrary spheres for H atoms), dashed line indicates hydrogen bonding.
	Fig. 2. A diagram showing π-π stacking [symmetry codes: (i) 2 - x,1 - y,1 - z; (ii) 1 - x,-y,1 - z].

(E)-2-Acetylpyrazine 4-nitrophenylhydrazone

Crystal data

C12H11N5O2	F(000) = 536
Mr = 257.26	Dx = 1.419 Mg m^−3
Monoclinic, P21/n	Melting point: 498 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71069 Å
a = 8.0101 (6) Å	Cell parameters from 4236 reflections
b = 12.5154 (11) Å	θ = 3.2–25.0°
c = 12.1506 (12) Å	µ = 0.10 mm^−1
β = 98.564 (2)°	T = 295 K
V = 1204.51 (18) Å^3	Prism, yellow
Z = 4	0.40 × 0.38 × 0.26 mm

Data collection

Rigaku R-AXIS RAPID IP diffractometer	1446 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.033
Graphite monochromator	θmax = 27.4°, θmin = 3.0°
Detector resolution: 10.00 pixels mm^-1	h = −10→10
ω scans	k = −16→16
11633 measured reflections	l = −15→15
2747 independent reflections

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)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.149	w = 1/[σ^2(Fo^2) + (0.0615P)^2 + 0.2787P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.001
2747 reflections	Δρmax = 0.20 e Å^−3
174 parameters	Δρmin = −0.19 e Å^−3
0 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: 0.024 (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 > 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
N1	0.9003 (3)	0.68785 (16)	0.3418 (2)	0.0684 (6)
N2	0.6332 (2)	0.36085 (12)	0.57394 (13)	0.0448 (4)
H2N	0.6470	0.3652	0.6496	0.054*
N3	0.5365 (2)	0.28334 (12)	0.51838 (13)	0.0425 (4)
N4	0.3197 (2)	0.04376 (14)	0.55830 (14)	0.0518 (5)
N5	0.2175 (2)	0.07812 (15)	0.33069 (14)	0.0571 (5)
O1	0.9806 (3)	0.75846 (16)	0.3955 (2)	0.1041 (8)
O2	0.8729 (3)	0.68826 (16)	0.2397 (2)	0.1012 (8)
C1	0.6976 (2)	0.43994 (15)	0.51344 (16)	0.0412 (5)
C2	0.7855 (3)	0.52394 (16)	0.57162 (17)	0.0490 (5)
H2	0.7989	0.5251	0.6490	0.059*
C3	0.8519 (3)	0.60439 (16)	0.51558 (18)	0.0521 (5)
H3	0.9109	0.6601	0.5544	0.062*
C4	0.8306 (3)	0.60198 (15)	0.40117 (18)	0.0488 (5)
C5	0.7461 (3)	0.51920 (17)	0.34168 (17)	0.0513 (5)
H5	0.7339	0.5187	0.2644	0.062*
C6	0.6803 (3)	0.43744 (17)	0.39758 (16)	0.0482 (5)
H6	0.6246	0.3809	0.3583	0.058*
C7	0.4778 (2)	0.20837 (14)	0.57459 (15)	0.0408 (5)
C8	0.5120 (3)	0.19727 (18)	0.69835 (17)	0.0593 (6)
H8A	0.6317	0.1939	0.7222	0.089*
H8B	0.4602	0.1331	0.7202	0.089*
H8C	0.4663	0.2578	0.7322	0.089*
C9	0.3700 (2)	0.13023 (15)	0.50718 (15)	0.0408 (5)
C10	0.3179 (3)	0.14575 (16)	0.39353 (16)	0.0496 (5)
H10	0.3553	0.2063	0.3602	0.059*
C11	0.1699 (3)	−0.00860 (18)	0.38283 (19)	0.0569 (6)
H11	0.1002	−0.0587	0.3424	0.068*
C12	0.2214 (3)	−0.02519 (17)	0.49398 (19)	0.0554 (6)
H12	0.1865	−0.0871	0.5263	0.067*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0742 (15)	0.0486 (11)	0.0895 (17)	0.0037 (10)	0.0352 (12)	0.0135 (11)
N2	0.0566 (11)	0.0430 (9)	0.0341 (8)	−0.0036 (8)	0.0039 (7)	−0.0005 (7)
N3	0.0478 (10)	0.0391 (8)	0.0397 (9)	0.0001 (7)	0.0036 (7)	−0.0009 (7)
N4	0.0623 (12)	0.0469 (10)	0.0465 (10)	−0.0033 (8)	0.0094 (8)	0.0044 (8)
N5	0.0678 (13)	0.0578 (11)	0.0435 (10)	−0.0075 (9)	0.0012 (9)	−0.0042 (9)
O1	0.1140 (18)	0.0645 (12)	0.137 (2)	−0.0350 (12)	0.0270 (15)	0.0119 (13)
O2	0.146 (2)	0.0841 (14)	0.0860 (15)	−0.0086 (13)	0.0569 (14)	0.0232 (12)
C1	0.0454 (11)	0.0388 (10)	0.0393 (10)	0.0033 (8)	0.0064 (8)	−0.0002 (8)
C2	0.0588 (13)	0.0456 (11)	0.0419 (11)	−0.0015 (10)	0.0050 (9)	−0.0038 (9)
C3	0.0542 (13)	0.0412 (11)	0.0609 (14)	−0.0029 (9)	0.0087 (10)	−0.0062 (10)
C4	0.0517 (12)	0.0405 (10)	0.0577 (13)	0.0055 (9)	0.0198 (10)	0.0075 (10)
C5	0.0610 (14)	0.0527 (12)	0.0414 (11)	0.0029 (10)	0.0117 (10)	0.0022 (10)
C6	0.0569 (13)	0.0471 (11)	0.0411 (11)	−0.0013 (10)	0.0088 (9)	−0.0023 (9)
C7	0.0469 (12)	0.0381 (10)	0.0370 (10)	0.0050 (8)	0.0046 (8)	0.0027 (8)
C8	0.0780 (17)	0.0573 (13)	0.0396 (12)	−0.0086 (12)	−0.0009 (11)	0.0065 (10)
C9	0.0459 (11)	0.0391 (10)	0.0379 (10)	0.0036 (8)	0.0079 (8)	0.0035 (8)
C10	0.0605 (14)	0.0483 (11)	0.0394 (11)	−0.0045 (10)	0.0060 (10)	0.0024 (9)
C11	0.0619 (15)	0.0520 (13)	0.0561 (13)	−0.0091 (11)	0.0064 (11)	−0.0063 (11)
C12	0.0634 (14)	0.0473 (12)	0.0568 (13)	−0.0107 (10)	0.0127 (11)	0.0019 (11)

Geometric parameters (Å, º)

N1—O1	1.223 (3)	C3—H3	0.9300
N1—O2	1.226 (3)	C4—C5	1.381 (3)
N1—C4	1.452 (3)	C5—C6	1.376 (3)
N2—N3	1.357 (2)	C5—H5	0.9300
N2—C1	1.378 (2)	C6—H6	0.9300
N2—H2N	0.9106	C7—C9	1.470 (3)
N3—C7	1.290 (2)	C7—C8	1.494 (3)
N4—C12	1.339 (3)	C8—H8A	0.9600
N4—C9	1.339 (2)	C8—H8B	0.9600
N5—C10	1.328 (3)	C8—H8C	0.9600
N5—C11	1.340 (3)	C9—C10	1.395 (3)
C1—C6	1.394 (3)	C10—H10	0.9300
C1—C2	1.397 (3)	C11—C12	1.368 (3)
C2—C3	1.367 (3)	C11—H11	0.9300
C2—H2	0.9300	C12—H12	0.9300
C3—C4	1.375 (3)
O1—N1—O2	122.5 (2)	C5—C6—C1	119.6 (2)
O1—N1—C4	118.7 (2)	C5—C6—H6	120.2
O2—N1—C4	118.8 (2)	C1—C6—H6	120.2
N3—N2—C1	118.65 (15)	N3—C7—C9	114.78 (16)
N3—N2—H2N	121.3	N3—C7—C8	125.00 (18)
C1—N2—H2N	119.8	C9—C7—C8	120.23 (17)
C7—N3—N2	118.88 (16)	C7—C8—H8A	109.5
C12—N4—C9	116.19 (18)	C7—C8—H8B	109.5
C10—N5—C11	115.78 (18)	H8A—C8—H8B	109.5
N2—C1—C6	122.25 (18)	C7—C8—H8C	109.5
N2—C1—C2	118.10 (17)	H8A—C8—H8C	109.5
C6—C1—C2	119.64 (19)	H8B—C8—H8C	109.5
C3—C2—C1	120.42 (19)	N4—C9—C10	120.35 (18)
C3—C2—H2	119.8	N4—C9—C7	118.11 (16)
C1—C2—H2	119.8	C10—C9—C7	121.53 (17)
C2—C3—C4	119.2 (2)	N5—C10—C9	123.13 (19)
C2—C3—H3	120.4	N5—C10—H10	118.4
C4—C3—H3	120.4	C9—C10—H10	118.4
C3—C4—C5	121.53 (19)	N5—C11—C12	121.6 (2)
C3—C4—N1	119.1 (2)	N5—C11—H11	119.2
C5—C4—N1	119.3 (2)	C12—C11—H11	119.2
C6—C5—C4	119.56 (19)	N4—C12—C11	122.9 (2)
C6—C5—H5	120.2	N4—C12—H12	118.6
C4—C5—H5	120.2	C11—C12—H12	118.6

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···N5^i	0.91	2.30	3.185 (2)	164
C11—H11···O1^ii	0.93	2.60	3.300 (3)	133

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