6-Nitro-2,3-bis­(thio­phen-2-yl)quinoxaline

Freitas, J.F. de; Brown, S.; Oberndorfer, J.S.; Crundwell, G.

doi:10.1107/S2414314620002035

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 5| Part 2| February 2020| x200203

https://doi.org/10.1107/S2414314620002035

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6-Nitro-2,3-bis(thiophen-2-yl)quinoxaline

Jorge F. de Freitas,^a Shayne Brown,^a James S. Oberndorfer ^a and Guy Crundwell ^a ^*

^aDepartment of Chemistry & Biochemistry, Central Connecticut State University, 1619 Stanley Street, New Britain, CT 06053, USA
^*Correspondence e-mail: crundwellg@ccsu.edu

Edited by K. Fejfarova, Institute of Biotechnology CAS, Czech Republic (Received 12 February 2020; accepted 12 February 2020; online 14 February 2020)

The title compound, C₁₆H₉N₃O₂S₂, was synthesized via a condensation reaction in refluxing acetic acid. One thienyl ring is nearly coplanar with the quinoxaline unit [dihedral angle = 3.29 (9)°], the other makes an angle of 83.96 (4)°.

Keywords: crystal structure; quinoxaline; thiophene.

CCDC reference: 1983315

Structure description

6-Nitro-2,3-bis(thiophen-2-yl)quinoxaline crystallizes in space group P2₁/c. All bond lengths and angles are within expected values. Unlike in the related molecule 5-nitro-2,3-bis(thiophen-2-yl)quinoxaline (de Freitas et al., 2020 ), one thienyl ring and the nitro group in the title compound are nearly coplanar with the quinoxaline moiety. The nitro group makes a dihedral angle of 7.76 (14)° with respect to the mean plane of the quinoxaline unit. A survey of the literature on other 6-nitroquinoxalines reveals that the nitro group is routinely nearly coplanar. The two thienyl rings make dihedral angles of 83.96 (4) and 3.29 (9)°, for the rings with S1 and S2 respectively, with the mean plane of the quinoxaline unit. The coplanar thienyl ring sulfur atom is closer in proximity to the quinoxaline nitrogen atom, in the trans arrangement of Du & Zhao (2003 ). The other thienyl ring is nearly perpendicular to the plane of the quinoxaline; barely adopting the aforementioned authors cis arrangement. There are no intermolecular interactions of consequence. An ORTEP view is shown in Fig. 1 and a view of the unit cell along (010) is shown in Fig. 2.

Figure 1
A view of 6-nitro-2,3-bis(thiophen-2-yl)quinoxaline (Farrugia, 2012

). Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A view of the unit cell of 6-nitro-2,3-bis(thiophen-2-yl)quinoxaline along (010).

Synthesis and crystallization

2-Thiophenecarboxaldehyde was condensed to 2,2′-thenoin (Crundwell et al., 2002 ) followed by oxidation to 2,2′-thenil (Crundwell et al., 2003 ). The nitrophenylenediamines were used as purchased from Sigma–Aldrich.

In a 100 ml round-bottom flask, 2.22 g of 2,2′-thenil (10.0 mmol) and 1.52 g of 4-nitro-1,2-phenylenediamine were added to 50 ml of concentrated acetic acid. The solution was refluxed with stirring for 18 h. The solution was cooled to room temperature and neutralized with 6 M NaOH. The solution was again cooled then filtered. The resulting solid was filtered and washed with cold water then dried. The yield of the yellow product was 3.10 g (92%), m.p. 474 K. ¹H NMR (CDCl₃, 300 MHz): δ = 7.10 (m, 2H), 7.43 (m, 2H), 7.61 (m, 2H), 8.20 (d, 1H), 8.49 (dd, 1H), 8.98 (d, 1H); ¹³C NMR (CDCl₃, 300 MHz): δ = 123.4, 125.2, 127.8, 127.9, 130.2, 130.3, 130.7, 139.3, 140.5, 140.8, 143.0, 147.8, 148.7, 149.3.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₆H₉N₃O₂S₂
M_r	339.38
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	11.7649 (4), 5.3386 (2), 24.3536 (8)
β (°)	105.610 (3)
V (Å³)	1473.18 (9)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.37
Crystal size (mm)	0.40 × 0.30 × 0.18

Data collection
Diffractometer	Oxford Diffraction Xcalibur, Sapphire3
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction, Yarnton, England.]$ )
T_min, T_max	0.871, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	12501, 5931, 3620
R_int	0.020
(sin θ/λ)_max (Å⁻¹)	0.802

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.062, 0.199, 1.06
No. of reflections	5931
No. of parameters	208
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.51, −0.33
Computer programs: CrysAlis CCD and CrysAlis RED (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction, Yarnton, England.]$ ), SHELXS2014 (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012 ) and OLEX2 (Bourhis et al., 2015 ).

Structural data

CCDC reference: 1983315

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314620002035/ff4034sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620002035/ff4034Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314620002035/ff4034Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: OLEX2 (Bourhis et al., 2015).

6-Nitro-2,3-bis(thiophen-2-yl)quinoxaline top

Crystal data top

C₁₆H₉N₃O₂S₂	D_x = 1.530 Mg m⁻³
M_r = 339.38	Melting point: 474 K
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.7649 (4) Å	Cell parameters from 4982 reflections
b = 5.3386 (2) Å	θ = 4.2–34.7°
c = 24.3536 (8) Å	µ = 0.37 mm⁻¹
β = 105.610 (3)°	T = 293 K
V = 1473.18 (9) Å³	Block, yellow
Z = 4	0.40 × 0.30 × 0.18 mm
F(000) = 696

Data collection top

Oxford Diffraction Xcalibur, Sapphire3 diffractometer	5931 independent reflections
Radiation source: fine-focus sealed tube	3620 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.020
phi and ω scans	θ_max = 34.7°, θ_min = 4.2°
Absorption correction: multi-scan (CrysAlisPro; Oxford Diffraction, 2009)	h = −18→18
T_min = 0.871, T_max = 1.000	k = −8→7
12501 measured reflections	l = −36→38

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)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.199	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0958P)² + 0.397P] where P = (F_o² + 2F_c²)/3
5931 reflections	(Δ/σ)_max = 0.001
208 parameters	Δρ_max = 0.51 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

H atoms were included in calculated positions with C-H distances of 0.93 Å and were included in the refinement in riding motion approximation with U_iso = 1.2 of the carrier atom.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
S1	0.16791 (7)	0.82603 (13)	0.52719 (3)	0.0622 (2)
S2	0.02258 (6)	1.15002 (14)	0.31003 (3)	0.0592 (2)
O1	0.30694 (18)	0.1759 (4)	0.20797 (8)	0.0669 (5)
O2	0.43910 (18)	−0.0612 (4)	0.26181 (9)	0.0663 (5)
N2	0.20929 (14)	0.7957 (3)	0.33911 (7)	0.0357 (3)
N1	0.36211 (14)	0.6752 (3)	0.44590 (7)	0.0369 (3)
N3	0.37406 (17)	0.1200 (4)	0.25404 (8)	0.0463 (4)
C1	0.27918 (15)	0.8444 (4)	0.44089 (8)	0.0328 (4)
C2	0.20193 (15)	0.9143 (3)	0.38578 (7)	0.0323 (3)
C3	0.29042 (16)	0.6090 (3)	0.34485 (8)	0.0322 (3)
C4	0.29411 (17)	0.4671 (4)	0.29649 (8)	0.0373 (4)
H4	0.2428	0.5008	0.2609	0.045*
C5	0.37543 (17)	0.2785 (4)	0.30344 (8)	0.0361 (4)
C6	0.45704 (19)	0.2266 (4)	0.35510 (9)	0.0445 (5)
H6	0.5124	0.0998	0.3576	0.053*
C7	0.45498 (19)	0.3639 (4)	0.40225 (9)	0.0442 (5)
H7	0.5094	0.3318	0.4370	0.053*
C8	0.37005 (16)	0.5542 (4)	0.39796 (8)	0.0343 (4)
C9	0.26743 (17)	0.9512 (4)	0.49523 (8)	0.0369 (4)
C10	0.3322 (2)	1.1441 (5)	0.52755 (8)	0.0452 (5)
H10	0.3919	1.2336	0.5179	0.054*
C11	0.2935 (2)	1.1845 (5)	0.57763 (9)	0.0529 (6)
H11	0.3249	1.3084	0.6042	0.063*
C12	0.2088 (2)	1.0296 (5)	0.58287 (10)	0.0567 (6)
H12	0.1756	1.0320	0.6135	0.068*
C13	0.11360 (16)	1.1131 (4)	0.37766 (8)	0.0351 (4)
C14	0.08780 (17)	1.2923 (4)	0.41567 (9)	0.0380 (4)
H14	0.1266	1.3051	0.4542	0.046*
C15	−0.0063 (2)	1.4494 (5)	0.38591 (12)	0.0545 (6)
H15	−0.0363	1.5785	0.4035	0.065*
C16	−0.0479 (2)	1.3957 (5)	0.33041 (13)	0.0607 (7)
H16	−0.1089	1.4836	0.3057	0.073*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0796 (5)	0.0583 (4)	0.0622 (4)	−0.0135 (3)	0.0425 (3)	−0.0078 (3)
S2	0.0561 (4)	0.0676 (4)	0.0461 (3)	0.0207 (3)	0.0002 (2)	0.0051 (3)
O1	0.0714 (12)	0.0817 (14)	0.0453 (10)	0.0018 (10)	0.0120 (8)	−0.0174 (9)
O2	0.0820 (13)	0.0516 (10)	0.0741 (12)	0.0145 (10)	0.0364 (10)	−0.0087 (9)
N2	0.0348 (7)	0.0401 (8)	0.0312 (7)	0.0049 (6)	0.0069 (6)	0.0012 (6)
N1	0.0352 (7)	0.0417 (9)	0.0318 (8)	0.0048 (7)	0.0057 (6)	0.0023 (6)
N3	0.0508 (10)	0.0464 (10)	0.0482 (10)	−0.0082 (8)	0.0248 (8)	−0.0092 (8)
C1	0.0307 (8)	0.0359 (9)	0.0317 (8)	0.0016 (7)	0.0080 (6)	0.0030 (7)
C2	0.0301 (8)	0.0337 (8)	0.0330 (8)	0.0012 (7)	0.0083 (6)	0.0026 (7)
C3	0.0313 (8)	0.0343 (8)	0.0313 (8)	0.0004 (7)	0.0091 (6)	0.0021 (7)
C4	0.0376 (9)	0.0420 (10)	0.0314 (8)	0.0030 (8)	0.0075 (7)	0.0020 (7)
C5	0.0374 (9)	0.0363 (9)	0.0381 (9)	−0.0019 (7)	0.0164 (7)	−0.0034 (7)
C6	0.0410 (10)	0.0443 (11)	0.0481 (11)	0.0107 (9)	0.0120 (8)	0.0010 (9)
C7	0.0389 (9)	0.0520 (12)	0.0389 (10)	0.0155 (9)	0.0056 (7)	0.0039 (9)
C8	0.0304 (8)	0.0392 (9)	0.0325 (8)	0.0026 (7)	0.0070 (6)	0.0023 (7)
C9	0.0382 (9)	0.0409 (10)	0.0318 (9)	0.0066 (8)	0.0097 (7)	0.0045 (7)
C10	0.0478 (11)	0.0561 (13)	0.0310 (9)	−0.0003 (10)	0.0091 (8)	−0.0035 (8)
C11	0.0652 (14)	0.0565 (14)	0.0345 (11)	0.0066 (12)	0.0091 (9)	−0.0050 (9)
C12	0.0774 (17)	0.0574 (14)	0.0433 (12)	0.0127 (13)	0.0302 (11)	0.0004 (10)
C13	0.0317 (8)	0.0354 (9)	0.0374 (9)	0.0026 (7)	0.0082 (7)	0.0032 (7)
C14	0.0367 (9)	0.0332 (9)	0.0433 (10)	0.0069 (7)	0.0092 (7)	0.0039 (7)
C15	0.0541 (13)	0.0411 (12)	0.0739 (17)	0.0140 (10)	0.0271 (12)	0.0075 (11)
C16	0.0462 (12)	0.0614 (15)	0.0714 (17)	0.0211 (11)	0.0103 (11)	0.0219 (13)

Geometric parameters (Å, º) top

S1—C9	1.707 (2)	C5—C6	1.390 (3)
S1—C12	1.703 (3)	C6—H6	0.9300
S2—C13	1.7171 (19)	C6—C7	1.368 (3)
S2—C16	1.696 (3)	C7—H7	0.9300
O1—N3	1.223 (3)	C7—C8	1.409 (3)
O2—N3	1.216 (3)	C9—C10	1.392 (3)
N2—C2	1.324 (2)	C10—H10	0.9300
N2—C3	1.361 (2)	C10—C11	1.428 (3)
N1—C1	1.311 (2)	C11—H11	0.9300
N1—C8	1.359 (2)	C11—C12	1.327 (4)
N3—C5	1.467 (3)	C12—H12	0.9300
C1—C2	1.453 (2)	C13—C14	1.420 (3)
C1—C9	1.481 (3)	C14—H14	0.9300
C2—C13	1.461 (3)	C14—C15	1.422 (3)
C3—C4	1.411 (3)	C15—H15	0.9300
C3—C8	1.408 (2)	C15—C16	1.339 (4)
C4—H4	0.9300	C16—H16	0.9300
C4—C5	1.368 (3)

C12—S1—C9	91.82 (12)	N1—C8—C3	120.51 (17)
C16—S2—C13	92.06 (12)	N1—C8—C7	119.36 (16)
C2—N2—C3	117.91 (15)	C3—C8—C7	120.06 (17)
C1—N1—C8	117.97 (16)	C1—C9—S1	119.81 (15)
O1—N3—C5	118.3 (2)	C10—C9—S1	111.71 (16)
O2—N3—O1	124.1 (2)	C10—C9—C1	128.42 (19)
O2—N3—C5	117.62 (19)	C9—C10—H10	125.0
N1—C1—C2	121.85 (17)	C9—C10—C11	110.0 (2)
N1—C1—C9	115.35 (16)	C11—C10—H10	125.0
C2—C1—C9	122.76 (16)	C10—C11—H11	122.9
N2—C2—C1	120.08 (16)	C12—C11—C10	114.1 (2)
N2—C2—C13	116.08 (16)	C12—C11—H11	122.9
C1—C2—C13	123.84 (16)	S1—C12—H12	123.8
N2—C3—C4	119.05 (16)	C11—C12—S1	112.30 (18)
N2—C3—C8	121.41 (17)	C11—C12—H12	123.8
C8—C3—C4	119.54 (17)	C2—C13—S2	116.76 (14)
C3—C4—H4	121.0	C14—C13—S2	111.13 (14)
C5—C4—C3	118.00 (17)	C14—C13—C2	132.09 (17)
C5—C4—H4	121.0	C13—C14—H14	125.1
C4—C5—N3	118.04 (18)	C13—C14—C15	109.80 (19)
C4—C5—C6	123.28 (18)	C15—C14—H14	125.1
C6—C5—N3	118.66 (19)	C14—C15—H15	122.8
C5—C6—H6	120.4	C16—C15—C14	114.3 (2)
C7—C6—C5	119.27 (19)	C16—C15—H15	122.8
C7—C6—H6	120.4	S2—C16—H16	123.7
C6—C7—H7	120.1	C15—C16—S2	112.70 (18)
C6—C7—C8	119.78 (19)	C15—C16—H16	123.7
C8—C7—H7	120.1

Funding information

This research was funded by a CCSU–AAUP research grant.

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