Quinoxaline: Z′ = 1 form

Ranganathan, S.; Mahapatra, S.; Thakur, T.S.; Desiraju, G.R.

doi:10.1107/S1600536810039905

organic compounds

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ISSN: 2056-9890

Volume 66| Part 11| November 2010| Page o2789

https://doi.org/10.1107/S1600536810039905

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Quinoxaline: Z′ = 1 form

Sathishkumar Ranganathan,^a Sudarshan Mahapatra,^a Tejender S. Thakur ^a and Gautam R. Desiraju ^a ^*

^aSolid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India
^*Correspondence e-mail: desiraju@sscu.iisc.ernet.in

(Received 28 September 2010; accepted 6 October 2010; online 9 October 2010)

A new Z′ = 1 crystal structure of quinoxaline (or 1,4-diazanaphthalene), C₈H₆N₂, with one-fifth the volume of the earlier known Z′ = 5 structure was obtained by means of an in situ cryocrystallization technique.

Related literature

For the structure of quinoxaline Z′ = 5, see: Anthony et al. (1998 ). For the crystal structure of the hydrated organic compound, see: Namba et al. (1981 ).

Experimental

Crystal data

C₈H₆N₂
M_r = 130.15
Orthorhombic, P 2₁ 2₁ 2₁
a = 4.0212 (13) Å
b = 7.187 (2) Å
c = 23.095 (7) Å
V = 667.5 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 270 K
0.40 × 0.30 × 0.30 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.968, T_max = 0.976
7556 measured reflections
956 independent reflections
494 reflections with I > 2σ(I)
R_int = 0.045

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.106
S = 0.90
956 reflections
91 parameters
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: SMART (Bruker, 1998 ); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810039905/ds2061sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810039905/ds2061Isup2.hkl

checkCIF report

Related literature top

For the structure of quinoxaline Z' = 5, see: Anthony et al. (1998). For the crystal structure of the hydrated organic compound, see: Namba et al. (1981)

Experimental top

For in situ crystallization, liquid quinoxaline was taken in a Lindemann glass capillary of 0.5 mm diameter. The Z' = 1 form of quinoxaline was obtained by sudden quenching of a capillary, kept in a hot water bath at 70 ^oC, down to liquid N₂ temperature.The capillary was aligned on a Bruker AXS Smart Apex diffractometer and data was collected at 270 K under a liquid N₂ flow using the OXFORD N₂ cryosystems appratus.

Structure description top

For the structure of quinoxaline Z' = 5, see: Anthony et al. (1998). For the crystal structure of the hydrated organic compound, see: Namba et al. (1981)

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top

Fig. 1. View of the title compound with the atom numbering. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.

Quinoxaline top

Crystal data top

C₈H₆N₂	D_x = 1.295 Mg m⁻³
M_r = 130.15	Melting point = 301–305 K
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 734 reflections
a = 4.0212 (13) Å	θ = 1.8–26.0°
b = 7.187 (2) Å	µ = 0.08 mm⁻¹
c = 23.095 (7) Å	T = 270 K
V = 667.5 (3) Å³	Block, pink
Z = 4	0.40 × 0.30 × 0.30 mm
F(000) = 272

Data collection top

Bruker SMART CCD area-detector diffractometer	956 independent reflections
Radiation source: fine-focus sealed tube	494 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.045
φ and ω scans	θ_max = 27.9°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −5→5
T_min = 0.968, T_max = 0.976	k = −9→9
7556 measured reflections	l = −29→29

Refinement top

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.106	H-atom parameters constrained
S = 0.90	w = 1/[σ²(F_o²) + (0.0652P)²] where P = (F_o² + 2F_c²)/3
956 reflections	(Δ/σ)_max < 0.001
91 parameters	Δρ_max = 0.13 e Å⁻³
0 restraints	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₈H₆N₂	V = 667.5 (3) Å³
M_r = 130.15	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 4.0212 (13) Å	µ = 0.08 mm⁻¹
b = 7.187 (2) Å	T = 270 K
c = 23.095 (7) Å	0.40 × 0.30 × 0.30 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	956 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	494 reflections with I > 2σ(I)
T_min = 0.968, T_max = 0.976	R_int = 0.045
7556 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.106	H-atom parameters constrained
S = 0.90	Δρ_max = 0.13 e Å⁻³
956 reflections	Δρ_min = −0.15 e Å⁻³
91 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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

	x	y	z	U_iso*/U_eq
N1	0.2099 (7)	0.1700 (3)	0.11405 (9)	0.1298 (9)
N2	0.2375 (6)	0.4337 (3)	0.20264 (7)	0.1131 (8)
C3	0.3379 (8)	0.1356 (3)	0.16499 (13)	0.1287 (13)
C4	0.3497 (7)	0.2654 (4)	0.20858 (9)	0.1197 (10)
C5	−0.0218 (7)	0.6547 (3)	0.13897 (10)	0.1051 (9)
C6	−0.1499 (7)	0.6977 (3)	0.08739 (11)	0.1121 (10)
C7	−0.1662 (7)	0.5672 (4)	0.04429 (10)	0.1201 (10)
C8	−0.0500 (9)	0.3930 (4)	0.05303 (8)	0.1210 (10)
C9	0.0873 (6)	0.3450 (2)	0.10587 (8)	0.0900 (8)
C10	0.1023 (6)	0.4767 (3)	0.14993 (7)	0.0842 (7)
H3	0.42490	0.01780	0.17200	0.1550*
H4	0.44230	0.23130	0.24390	0.1440*
H5	−0.01510	0.74440	0.16800	0.1260*
H6	−0.22890	0.81740	0.08070	0.1340*
H7	−0.25820	0.59880	0.00870	0.1440*
H8	−0.06220	0.30540	0.02350	0.1450*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.175 (2)	0.0880 (13)	0.1265 (15)	0.0079 (13)	−0.0063 (15)	−0.0159 (10)
N2	0.1395 (18)	0.1161 (14)	0.0837 (11)	−0.0085 (13)	−0.0069 (11)	−0.0063 (9)
C3	0.156 (3)	0.0884 (14)	0.1418 (19)	0.0102 (16)	0.003 (2)	0.0182 (15)
C4	0.134 (2)	0.1240 (18)	0.1012 (14)	0.002 (2)	−0.0040 (16)	0.0271 (14)
C5	0.131 (2)	0.0819 (13)	0.1025 (14)	0.0005 (13)	0.0090 (14)	−0.0123 (10)
C6	0.1148 (19)	0.0976 (14)	0.1238 (17)	0.0038 (14)	0.0150 (17)	0.0233 (14)
C7	0.120 (2)	0.154 (2)	0.0862 (13)	−0.0023 (19)	−0.0026 (14)	0.0241 (16)
C8	0.160 (2)	0.1223 (17)	0.0806 (13)	0.0018 (19)	−0.0101 (16)	−0.0157 (12)
C9	0.1152 (17)	0.0750 (10)	0.0797 (11)	−0.0063 (12)	0.0067 (12)	−0.0083 (8)
C10	0.1008 (16)	0.0802 (10)	0.0717 (10)	−0.0131 (12)	0.0090 (10)	−0.0034 (8)

Geometric parameters (Å, º) top

N1—C3	1.308 (4)	C8—C9	1.383 (3)
N1—C9	1.364 (3)	C9—C10	1.391 (3)
N2—C4	1.298 (4)	C3—H3	0.9300
N2—C10	1.369 (3)	C4—H4	0.9300
C3—C4	1.373 (4)	C5—H5	0.9300
C5—C6	1.334 (4)	C6—H6	0.9300
C5—C10	1.396 (3)	C7—H7	0.9300
C6—C7	1.369 (4)	C8—H8	0.9300
C7—C8	1.352 (4)

N1···N2	2.791 (3)	H4···N2^v	2.7900
N2···N1	2.791 (3)	H7···C6^vi	3.0900
N2···H4ⁱ	2.7900	H8···C8ⁱⁱⁱ	3.0000
C6···H7ⁱⁱ	3.0900	H8···C8^iv	3.0700
C8···H8ⁱⁱⁱ	3.0700	H8···H8ⁱⁱⁱ	2.4200
C8···H8^iv	3.0000	H8···H8^iv	2.4200

C3—N1—C9	116.2 (2)	C5—C10—C9	118.38 (18)
C4—N2—C10	116.26 (19)	N1—C3—H3	118.00
N1—C3—C4	123.0 (2)	C4—C3—H3	119.00
N2—C4—C3	122.9 (2)	N2—C4—H4	119.00
C6—C5—C10	120.8 (2)	C3—C4—H4	119.00
C5—C6—C7	120.6 (2)	C6—C5—H5	120.00
C6—C7—C8	120.6 (2)	C10—C5—H5	120.00
C7—C8—C9	120.1 (2)	C5—C6—H6	120.00
N1—C9—C8	119.77 (19)	C7—C6—H6	120.00
N1—C9—C10	120.69 (19)	C6—C7—H7	120.00
C8—C9—C10	119.54 (18)	C8—C7—H7	120.00
N2—C10—C5	120.67 (19)	C7—C8—H8	120.00
N2—C10—C9	121.0 (2)	C9—C8—H8	120.00

C9—N1—C3—C4	0.3 (4)	C10—C5—C6—C7	0.8 (4)
C3—N1—C9—C10	0.3 (4)	C5—C6—C7—C8	−0.6 (4)
C3—N1—C9—C8	179.5 (3)	C6—C7—C8—C9	−0.1 (5)
C10—N2—C4—C3	0.3 (4)	C7—C8—C9—C10	0.5 (4)
C4—N2—C10—C5	−179.3 (2)	C7—C8—C9—N1	−178.8 (3)
C4—N2—C10—C9	0.3 (4)	N1—C9—C10—N2	−0.6 (4)
N1—C3—C4—N2	−0.7 (5)	C8—C9—C10—C5	−0.3 (4)
C6—C5—C10—C9	−0.4 (4)	N1—C9—C10—C5	179.0 (2)
C6—C5—C10—N2	179.2 (3)	C8—C9—C10—N2	−179.8 (3)

Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) x+1/2, −y+3/2, −z; (iii) x−1/2, −y+1/2, −z; (iv) x+1/2, −y+1/2, −z; (v) −x+1, y−1/2, −z+1/2; (vi) x−1/2, −y+3/2, −z.

Experimental details

Crystal data
Chemical formula	C₈H₆N₂
M_r	130.15
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	270
a, b, c (Å)	4.0212 (13), 7.187 (2), 23.095 (7)
V (Å³)	667.5 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.40 × 0.30 × 0.30

Data collection
Diffractometer	Bruker SMART CCD area-detector
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.968, 0.976
No. of measured, independent and observed [I > 2σ(I)] reflections	7556, 956, 494
R_int	0.045
(sin θ/λ)_max (Å⁻¹)	0.658

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.106, 0.90
No. of reflections	956
No. of parameters	91
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.13, −0.15

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SHELXTL (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), PLATON (Spek, 2009).

Selected geometric parameters (Å, º) top

N1—C3	1.308 (4)	N2—C4	1.298 (4)
N1—C9	1.364 (3)	N2—C10	1.369 (3)

C3—N1—C9	116.2 (2)	N1—C9—C8	119.77 (19)
C4—N2—C10	116.26 (19)	N1—C9—C10	120.69 (19)
N1—C3—C4	123.0 (2)	N2—C10—C5	120.67 (19)
N2—C4—C3	122.9 (2)	N2—C10—C9	121.0 (2)

Acknowledgements

TST thanks the Indian Institute of Science for a post-doctoral fellowship and GRD thanks the DST for the award of a J. C. Bose fellowship. We also thank Professor T. N. Guru Row for useful discussions.

References

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