Quinoxaline: Z' = 1 form.

A new Z' = 1 crystal structure of quinoxaline (or 1,4-diaza-naphthalene), C(8)H(6)N(2), 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 = 130.15

Orthorhombic,

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[F 2 > 2σ(F 2)] = 0.038

wR(F 2) = 0.106

S = 0.90

956 reflections

91 parameters

H-atom parameters constrained

Δρmax = 0.13 e Å−3

Δρmin = −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 ▶).

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

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810039905/ds2061Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C8H6N2	Dx = 1.295 Mg m−3
Mr = 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

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

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(Fo2) + (0.0652P)2] where P = (Fo2 + 2Fc2)/3
956 reflections	(Δ/σ)max < 0.001
91 parameters	Δρmax = 0.13 e Å−3
0 restraints	Δρmin = −0.15 e Å−3

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.

	x	y	z	Uiso*/Ueq
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*

	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)

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···N2v	2.7900
N2···N1	2.791 (3)	H7···C6vi	3.0900
N2···H4i	2.7900	H8···C8iii	3.0000
C6···H7ii	3.0900	H8···C8iv	3.0700
C8···H8iii	3.0700	H8···H8iii	2.4200
C8···H8iv	3.0000	H8···H8iv	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)