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

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

doi:10.1107/S2414314620001960

organic compounds

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ISSN: 2414-3146

Volume 5| Part 2| February 2020| x200196

https://doi.org/10.1107/S2414314620001960

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5-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 16 January 2020; accepted 11 February 2020; online 14 February 2020)

The title compound, C₁₆H₉N₃O₂S₂, was synthesized via a condensation reaction in refluxing acetic acid. The dihedral angles between the mean plane of the quinoxaline unit and the thienyl rings are 35.16 (5)° and 24.94 (3)°.

Keywords: crystal structure; quinoxaline; thiophene.

CCDC reference: 1983314

Structure description

5-Nitro-2,3-bis(thiophen-2-yl)quinoxaline crystallizes in space group P2₁. All bond lengths and angles are within expected values. The nitro group makes a angle of 43.07 (6)° with respect to the mean plane of the quinoxaline unit. This angle is comparable to the angles of 44.96 and 50.93° observed for the two molecules in the asymmetric unit in the published crystal structure of 5-nitro-2,3-bis(2-pyridyl)quinoxaline (Du & Zhao, 2003 ) and with the 44.12° determined in a corresponding silver complex with the pyridyl ligand (Liu & Du, 2002 ). The thienyl rings make angles of 35.16 (5) and 24.94 (3)°, for rings with S1 and S2 respectively, with the mean plane of the quinoxaline unit. Both the heterocyclic thienyl ring sulfur atoms reside in close proximity to the quinoxaline N atoms. When describing the structure of 5-nitro-2,3-bis(2-pyridyl)quinoxaline, Du & Zhao (2003) labeled this orientation of the heterocyclic ring to the quinoxaline unit as a trans–trans 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 5-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 5-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 3-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 2.80 g (83%), m.p. 445 K. Crystals were obtained by recrystallization from ethanol solution. ¹H NMR (CDCl₃, 300 MHz): δ = 7.17 (m, 2H), 7.42 (dd, 1H), 7.49 (dd, 1H), 7.80 (m, 2H), 7.97 (t, 1H), 8.30 (m, 2H); ¹³C NMR (CDCl₃, 300 MHz): δ = 124.4, 127.7, 127.8, 128.8, 130.2, 130.3, 130.5, 131.0, 132.1, 132.8, 140.1, 140.5, 141.0, 147.0, 148.0, 148.1.

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
Temperature (K)	293
a, b, c (Å)	9.6598 (4), 7.4249 (3), 11.2457 (6)
β (°)	109.745 (5)
V (Å³)	759.15 (6)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.36
Crystal size (mm)	0.42 × 0.34 × 0.21

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	0.865, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	12526, 6073, 3455
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.802

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.076, 0.81
No. of reflections	6073
No. of parameters	208
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.15
Absolute structure	Flack (1983 )
Absolute structure parameter	0.02 (4)
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: 1983314

Crystal structure: contains datablock 10gc15. DOI: https://doi.org/10.1107/S2414314620001960/ff4033sup1.cif

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).

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

Crystal data top

C₁₆H₉N₃O₂S₂	D_x = 1.485 Mg m⁻³
M_r = 339.38	Melting point: 445 K
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
a = 9.6598 (4) Å	Cell parameters from 4761 reflections
b = 7.4249 (3) Å	θ = 4.2–34.7°
c = 11.2457 (6) Å	µ = 0.36 mm⁻¹
β = 109.745 (5)°	T = 293 K
V = 759.15 (6) Å³	Block, yellow
Z = 2	0.42 × 0.34 × 0.21 mm
F(000) = 348

Data collection top

Oxford Diffraction Xcalibur, Sapphire3 diffractometer	6073 independent reflections
Radiation source: Enhance (Mo) X-ray Source	3455 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
Detector resolution: 16.1790 pixels mm^-1	θ_max = 34.7°, θ_min = 4.2°
ω scans	h = −14→15
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	k = −11→11
T_min = 0.865, T_max = 1.000	l = −17→17
12526 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.076	w = 1/[σ²(F_o²) + (0.0401P)²] where P = (F_o² + 2F_c²)/3
S = 0.81	(Δ/σ)_max < 0.001
6073 reflections	Δρ_max = 0.43 e Å⁻³
208 parameters	Δρ_min = −0.15 e Å⁻³
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: iterative	Absolute structure parameter: 0.02 (4)

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	0.47899 (5)	0.46766 (7)	0.76512 (4)	0.06021 (14)
S2	−0.19846 (4)	0.56574 (5)	0.45980 (4)	0.04714 (10)
O1	−0.14872 (15)	0.6115 (2)	0.11787 (12)	0.0794 (4)
O2	−0.12755 (18)	0.3929 (3)	0.00033 (12)	0.0978 (6)
N1	0.33895 (13)	0.50828 (18)	0.48400 (11)	0.0434 (3)
N2	0.03464 (12)	0.50012 (16)	0.35820 (10)	0.0368 (3)
N3	−0.07726 (18)	0.4977 (3)	0.08793 (12)	0.0608 (4)
C1	0.24643 (14)	0.52968 (18)	0.54672 (12)	0.0358 (3)
C2	0.08928 (14)	0.51352 (17)	0.48202 (12)	0.0324 (3)
C3	0.13010 (16)	0.4937 (2)	0.29286 (13)	0.0390 (3)
C4	0.08067 (17)	0.4805 (2)	0.16013 (13)	0.0473 (4)
C5	0.1750 (2)	0.4561 (3)	0.09426 (17)	0.0645 (5)
H5	0.1394	0.4464	0.0067	0.077*
C6	0.3257 (2)	0.4459 (3)	0.16079 (18)	0.0727 (6)
H6	0.3903	0.4287	0.1164	0.087*
C7	0.3801 (2)	0.4603 (3)	0.28792 (17)	0.0647 (5)
H7	0.4811	0.4537	0.3299	0.078*
C8	0.28385 (16)	0.4853 (2)	0.35731 (14)	0.0435 (3)
C9	0.31323 (14)	0.5671 (2)	0.68209 (12)	0.0378 (3)
C10	0.26900 (17)	0.6793 (2)	0.75847 (14)	0.0447 (4)
H10	0.1831	0.7472	0.7308	0.054*
C11	0.36745 (19)	0.6812 (2)	0.88351 (15)	0.0554 (4)
H11	0.3529	0.7491	0.9478	0.066*
C12	0.48426 (19)	0.5748 (3)	0.90005 (15)	0.0630 (5)
H12	0.5599	0.5610	0.9769	0.076*
C13	−0.02054 (14)	0.50573 (18)	0.54585 (12)	0.0332 (3)
C14	−0.01082 (17)	0.4470 (2)	0.66529 (14)	0.0452 (4)
H14	0.0756	0.4075	0.7262	0.054*
C15	−0.1486 (2)	0.4545 (3)	0.68296 (16)	0.0554 (4)
H15	−0.1625	0.4191	0.7574	0.066*
C16	−0.25747 (19)	0.5175 (2)	0.58246 (17)	0.0552 (5)
H16	−0.3539	0.5329	0.5802	0.066*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0398 (2)	0.0812 (3)	0.0524 (2)	0.0186 (2)	0.00605 (16)	0.0062 (2)
S2	0.03174 (17)	0.0601 (2)	0.0503 (2)	0.00166 (19)	0.01476 (14)	−0.0002 (2)
O1	0.0607 (8)	0.1124 (12)	0.0540 (8)	0.0145 (9)	0.0049 (6)	−0.0004 (8)
O2	0.0919 (11)	0.1455 (15)	0.0512 (8)	−0.0414 (11)	0.0180 (7)	−0.0355 (9)
N1	0.0313 (5)	0.0576 (8)	0.0441 (7)	0.0034 (5)	0.0163 (5)	0.0023 (6)
N2	0.0324 (5)	0.0459 (7)	0.0336 (6)	−0.0032 (5)	0.0130 (4)	−0.0010 (5)
N3	0.0650 (9)	0.0883 (11)	0.0270 (6)	−0.0192 (9)	0.0130 (6)	−0.0009 (7)
C1	0.0309 (6)	0.0381 (9)	0.0380 (7)	0.0006 (5)	0.0110 (5)	0.0010 (6)
C2	0.0299 (6)	0.0335 (7)	0.0359 (7)	0.0008 (5)	0.0137 (5)	0.0011 (5)
C3	0.0416 (7)	0.0408 (7)	0.0388 (7)	−0.0044 (7)	0.0193 (6)	−0.0011 (6)
C4	0.0517 (9)	0.0560 (9)	0.0362 (7)	−0.0060 (8)	0.0172 (6)	−0.0046 (7)
C5	0.0788 (13)	0.0810 (12)	0.0454 (9)	−0.0026 (12)	0.0363 (9)	−0.0057 (10)
C6	0.0749 (13)	0.0977 (15)	0.0651 (12)	0.0070 (12)	0.0494 (11)	−0.0044 (11)
C7	0.0481 (9)	0.0942 (14)	0.0624 (11)	0.0057 (10)	0.0326 (8)	−0.0038 (11)
C8	0.0393 (7)	0.0503 (8)	0.0463 (8)	0.0020 (7)	0.0214 (6)	−0.0015 (7)
C9	0.0300 (6)	0.0451 (7)	0.0361 (7)	0.0024 (7)	0.0085 (5)	0.0068 (7)
C10	0.0380 (8)	0.0513 (9)	0.0404 (8)	0.0033 (7)	0.0074 (6)	−0.0021 (7)
C11	0.0552 (10)	0.0658 (11)	0.0422 (9)	−0.0047 (9)	0.0126 (7)	−0.0075 (8)
C12	0.0515 (9)	0.0874 (13)	0.0394 (8)	0.0023 (11)	0.0014 (7)	0.0092 (10)
C13	0.0286 (6)	0.0369 (7)	0.0355 (7)	−0.0008 (5)	0.0125 (5)	−0.0013 (6)
C14	0.0446 (8)	0.0523 (9)	0.0424 (8)	−0.0013 (8)	0.0195 (6)	0.0057 (7)
C15	0.0598 (10)	0.0686 (11)	0.0483 (9)	−0.0147 (10)	0.0321 (8)	−0.0071 (9)
C16	0.0420 (8)	0.0686 (12)	0.0664 (11)	−0.0068 (8)	0.0331 (8)	−0.0123 (9)

Geometric parameters (Å, º) top

S1—C9	1.7234 (14)	C5—C6	1.396 (3)
S1—C12	1.6986 (19)	C6—H6	0.9300
S2—C13	1.7219 (14)	C6—C7	1.351 (2)
S2—C16	1.6992 (17)	C7—H7	0.9300
O1—N3	1.209 (2)	C7—C8	1.414 (2)
O2—N3	1.220 (2)	C9—C10	1.365 (2)
N1—C1	1.3218 (17)	C10—H10	0.9300
N1—C8	1.3528 (19)	C10—C11	1.407 (2)
N2—C2	1.3155 (17)	C11—H11	0.9300
N2—C3	1.3602 (17)	C11—C12	1.338 (2)
N3—C4	1.472 (2)	C12—H12	0.9300
C1—C2	1.4498 (18)	C13—C14	1.3849 (19)
C1—C9	1.4653 (19)	C14—H14	0.9300
C2—C13	1.4693 (18)	C14—C15	1.411 (2)
C3—C4	1.409 (2)	C15—H15	0.9300
C3—C8	1.417 (2)	C15—C16	1.341 (3)
C4—C5	1.367 (2)	C16—H16	0.9300
C5—H5	0.9300

C12—S1—C9	91.46 (8)	N1—C8—C3	120.30 (12)
C16—S2—C13	91.95 (8)	N1—C8—C7	119.98 (14)
C1—N1—C8	118.73 (12)	C3—C8—C7	119.66 (14)
C2—N2—C3	118.14 (12)	C1—C9—S1	118.96 (11)
O1—N3—O2	124.17 (17)	C10—C9—S1	110.59 (10)
O1—N3—C4	119.36 (15)	C10—C9—C1	130.37 (13)
O2—N3—C4	116.47 (19)	C9—C10—H10	123.7
N1—C1—C2	120.28 (12)	C9—C10—C11	112.66 (14)
N1—C1—C9	115.93 (12)	C11—C10—H10	123.7
C2—C1—C9	123.78 (12)	C10—C11—H11	123.6
N2—C2—C1	121.01 (12)	C12—C11—C10	112.76 (15)
N2—C2—C13	114.61 (11)	C12—C11—H11	123.6
C1—C2—C13	124.37 (12)	S1—C12—H12	123.7
N2—C3—C4	121.73 (13)	C11—C12—S1	112.51 (12)
N2—C3—C8	120.66 (13)	C11—C12—H12	123.7
C8—C3—C4	117.41 (12)	C2—C13—S2	117.62 (10)
C3—C4—N3	119.71 (13)	C14—C13—S2	110.76 (10)
C5—C4—N3	117.98 (14)	C14—C13—C2	131.50 (13)
C5—C4—C3	122.29 (15)	C13—C14—H14	124.3
C4—C5—H5	120.6	C13—C14—C15	111.45 (14)
C4—C5—C6	118.83 (16)	C15—C14—H14	124.3
C6—C5—H5	120.6	C14—C15—H15	123.1
C5—C6—H6	119.1	C16—C15—C14	113.81 (14)
C7—C6—C5	121.71 (15)	C16—C15—H15	123.1
C7—C6—H6	119.1	S2—C16—H16	124.0
C6—C7—H7	120.0	C15—C16—S2	112.01 (12)
C6—C7—C8	120.09 (17)	C15—C16—H16	124.0
C8—C7—H7	120.0

Funding information

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

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