2-(2-Thien­yl)quinoxaline

The crystal structure of the title compound, C₁₂H₈N₂S, was determined at 293 K. The mol­ecule is planar and packs in a herring-bone pattern.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.045
• wR factor = 0.112
• Data-to-parameter ratio = 34.8

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF020_ALERT_1_A  _diffrn_standards_interval_count and
            _diffrn_standards_interval_time are missing. Number of measurements
            between standards or time (min) between standards.

Alert level B
PLAT021_ALERT_1_B Ratio Unique / Expected Reflections too High ...       1.60

Alert level C
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.99
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C6     -   C7      ..       6.54 su

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

   4 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
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

We have previously investigated the crystal structures of 2,3-dithienylquinoxalines (Crundwell, Sayers et al., 2003) and bromo-substituted 2,3-dithienylquinoxalines (Crundwell et al., 2004). Quinoxalines, in general, have shown versatility in binding a wide variety of metals. We have now expanded our studies to the monosubstituted thienylquinoxalines.

The title compound, (I), sits on a general position. All bond lengths and angles are in agreement with those of other published quinoxalines and thienyl-containing compounds. Thienyl ring geometries and difference maps show no evidence of thienyl ring flip disorders, which are common in molecules with unsubstituted thienyl rings (Crundwell, Sullivan et al., 2003). Like 2-phenylquinoxaline (Qingchuan & Yili, 1989) and 2-(2'-pyridyl)quinoxaline (Kasselouri et al., 1994), the molecule is planar and packs in a herringbone motif. The interplanar spacing for layers in (I) is 3.537 Å, whereas the interplanar spacings for 2-phenyl and 2-(2'-pyridiyl)quinoxalines are 3.428 and 3.490 Å, respectively.

S2. Experimental

Equal molar amounts of thiophen-2-ylglyoxal and 1,2-phenylenediamine were refluxed in 95% ethanol for 2 h. The resulting mixture was filtered and washed with ice-cold ethanol. The precipitate was recrystallized from a boiling ethanol–toluene mixture and crystals were grown from slowly evaporated solutions of ethanol. A light-brown plate that displayed homogeneous birefringence was mounted for diffraction studies. ¹H NMR and UV–vis spectroscopies, as well as melting points of the title compound, agree with literature values (Peter et al., 2004 or?? 1995).

S3. Refinement

H atoms were found in difference maps and their positional parameters were refined. The U_iso(H) values were set at 0.05 Ų

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Bruno et al., 2002); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures

	Fig. 1. A view of (I) (Farrugia, 1997). Displacement ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.
	Fig. 2. Packing diagram for (I) (Bruno et al., 2002), showing the herringbone motif as viewed along the [001] direction.

2-(2-thienyl)quinoxaline

Crystal data

C12H8N2S	F(000) = 440
Mr = 212.27	Dx = 1.359 Mg m^−3
Monoclinic, P21/c	Melting point: 383 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 5.5062 (13) Å	Cell parameters from 1179 reflections
b = 16.119 (3) Å	θ = 3.8–29.7°
c = 11.939 (3) Å	µ = 0.28 mm^−1
β = 101.77 (2)°	T = 293 K
V = 1037.4 (4) Å^3	Plate, light brown
Z = 4	0.32 × 0.16 × 0.09 mm

Data collection

Sapphire3 diffractometer	2529 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.032
ω scans	θmax = 29.7°, θmin = 4.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −6→7
Tmin = 0.891, Tmax = 0.989	k = −22→22
8510 measured reflections	l = −16→12
4739 independent reflections

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.045	Only H-atom coordinates refined
wR(F^2) = 0.112	Weighting scheme: Prince modified Chebychev oplynomial (Watkin, 1994, Prince, 1982) [weight] = 1.0/[3.05T0(x) + 3.88T1(x) + 0.969T3(x)], where x = F /Fmax
S = 1.00	(Δ/σ)max = 0.001
4739 reflections	Δρmax = 0.58 e Å^−3
136 parameters	Δρmin = −0.80 e Å^−3
0 restraints

Special details

Refinement. The refinement was carried out against F and used a Chebychev polynomial where [weight] = 1.0/[A₀*T₀(x)+A₁*T₁(x) ··· +A_n-1]*T_n-1(x)], where A_i are the Chebychev coefficients (3.05, 3.88, 0.969, respectively), and where x= Fcalc/Fmax (Watkin, 1994, Prince, 1982). >>From Watkin's CRYSTAL manual: 7.34: Chebychev weighting schemes 10, 11 A[i] are the coefficients of a Chebyshev series (Rollett, 1965) in t[i]'(x), where x = F_o/F_o(max). For this weighting scheme, the coefficients a[i] are calculated by the program using a least squares procedure which minimizes sum[(F_o - Fc)**4] over all the reflections. The resulting coefficients are stored in a new LIST 4 as weighting scheme type 11 (see below), and then used to calculate the weights for each of the reflections. It is recommended that several different values of NP are used (e.g 3 to 5), so that series of various orders are tested to see which gives the best fit. If negative or very small reciprocal weights are computed (i.e. the computed curve fall close to or crosses the ordinate axis), the parameter MAXIMUM can be used to restrict the maximum weight. For data on 'ordinary' scales, this will require a value of about 100. (This is best seen by computing an agreement analysis once the new weights have been calculated). The parameters P(i) need not be given, because they are to be computed. When the Chebyshev coefficients have been determined, p(1) is overwritten by the value determined for a[1]. (Carruthers & Watkin, 1979). Scheme 10 generates the parameters needed for a scheme 11.

Rollett, J. S. (1965). Editor. Computing Methods in Crystallography, p. 40. Pergamon.

Carruthers, J. R. & Watkin, D. J. (1979). Acta Cryst. A35, 698–699.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.8214 (3)	0.77923 (9)	0.72525 (11)	0.0460
N1	0.7427 (2)	0.80309 (8)	0.81895 (10)	0.0475
C2	0.7110 (3)	0.81315 (11)	0.61546 (13)	0.0569
H2	0.7724	0.7950	0.5521	0.0500*
N2	0.5313 (3)	0.86703 (9)	0.59986 (11)	0.0614
C3	0.4454 (3)	0.89129 (9)	0.69575 (13)	0.0528
C4	0.2444 (3)	0.94720 (11)	0.68515 (16)	0.0670
H4	0.1707	0.9674	0.6136	0.0500*
C5	0.1597 (3)	0.97125 (11)	0.7795 (2)	0.0721
H5	0.0274	1.0088	0.7722	0.0500*
C6	0.2661 (4)	0.94083 (12)	0.88845 (17)	0.0726
H6	0.2045	0.9583	0.9516	0.0500*
C7	0.4608 (3)	0.88612 (11)	0.90199 (14)	0.0618
H7	0.5318	0.8668	0.9748	0.0500*
C8	0.5529 (3)	0.85915 (9)	0.80479 (12)	0.0485
S1	1.14778 (8)	0.68121 (3)	0.87275 (3)	0.0565
C9	1.0221 (3)	0.71880 (10)	0.73836 (11)	0.0461
C10	1.1429 (3)	0.68560 (10)	0.65719 (13)	0.0545
H10	1.1027	0.6991	0.5797	0.0500*
C11	1.3345 (3)	0.63111 (11)	0.70525 (14)	0.0594
H11	1.4341	0.6028	0.6628	0.0500*
C12	1.3589 (3)	0.62286 (10)	0.82045 (14)	0.0570
H12	1.4772	0.5887	0.8659	0.0500*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0507 (9)	0.0459 (9)	0.0402 (7)	−0.0120 (7)	0.0063 (6)	−0.0015 (6)
N1	0.0534 (7)	0.0489 (8)	0.0398 (6)	−0.0034 (6)	0.0086 (5)	−0.0017 (5)
C2	0.0666 (11)	0.0640 (11)	0.0392 (8)	−0.0067 (9)	0.0085 (7)	0.0011 (7)
N2	0.0675 (9)	0.0651 (10)	0.0463 (7)	−0.0033 (7)	−0.0010 (6)	0.0067 (6)
C3	0.0554 (9)	0.0441 (9)	0.0553 (9)	−0.0099 (7)	0.0026 (7)	0.0007 (7)
C4	0.0606 (10)	0.0580 (11)	0.0746 (12)	−0.0033 (9)	−0.0046 (9)	0.0085 (9)
C5	0.0577 (11)	0.0539 (11)	0.1013 (16)	0.0075 (8)	0.0080 (10)	−0.0017 (10)
C6	0.0784 (13)	0.0656 (12)	0.0770 (12)	0.0032 (10)	0.0237 (11)	−0.010 (1)
C7	0.0721 (11)	0.0593 (11)	0.0548 (9)	0.0083 (9)	0.0147 (8)	−0.0020 (8)
C8	0.0522 (9)	0.0436 (8)	0.0486 (8)	−0.0062 (7)	0.0077 (7)	−0.0016 (6)
S1	0.0677 (3)	0.0635 (3)	0.03713 (19)	0.0085 (2)	0.00795 (17)	−0.00498 (17)
C9	0.0535 (9)	0.0473 (9)	0.0375 (7)	−0.0081 (7)	0.0095 (6)	−0.0017 (6)
C10	0.0667 (10)	0.0565 (10)	0.0443 (8)	−0.0035 (8)	0.0208 (7)	0.0018 (7)
C11	0.0660 (10)	0.0625 (11)	0.0560 (10)	−0.0015 (8)	0.0271 (8)	−0.0071 (8)
C12	0.0588 (9)	0.0570 (10)	0.0536 (9)	0.0014 (8)	0.0076 (7)	−0.0073 (7)

Geometric parameters (Å, º)

C1—N1	1.3361 (17)	C6—H6	0.931
C1—C2	1.436 (2)	C6—C7	1.372 (3)
C1—C9	1.457 (2)	C7—H7	0.931
N1—C8	1.3658 (19)	C7—C8	1.426 (2)
C2—H2	0.936	S1—C9	1.7226 (15)
C2—N2	1.301 (2)	S1—C12	1.7091 (16)
N2—C3	1.381 (2)	C9—C10	1.3893 (19)
C3—C4	1.413 (2)	C10—H10	0.933
C3—C8	1.414 (2)	C10—C11	1.403 (2)
C4—H4	0.927	C11—H11	0.937
C4—C5	1.361 (3)	C11—C12	1.361 (2)
C5—H5	0.938	C12—H12	0.937
C5—C6	1.401 (3)
N1—C1—C2	120.36 (14)	C6—C7—H7	119.673
N1—C1—C9	118.09 (13)	C6—C7—C8	119.95 (16)
C2—C1—C9	121.55 (12)	H7—C7—C8	120.381
C1—N1—C8	117.23 (13)	C7—C8—C3	119.08 (15)
C1—C2—H2	117.630	C7—C8—N1	119.43 (14)
C1—C2—N2	123.57 (14)	C3—C8—N1	121.50 (13)
H2—C2—N2	118.795	C9—S1—C12	91.56 (8)
C2—N2—C3	116.69 (14)	C1—C9—S1	119.14 (9)
N2—C3—C4	120.04 (15)	C1—C9—C10	129.99 (13)
N2—C3—C8	120.63 (15)	S1—C9—C10	110.84 (12)
C4—C3—C8	119.30 (15)	C9—C10—H10	123.513
C3—C4—H4	119.650	C9—C10—C11	112.52 (14)
C3—C4—C5	120.13 (17)	H10—C10—C11	123.955
H4—C4—C5	120.216	C10—C11—H11	123.901
C4—C5—H5	119.852	C10—C11—C12	112.66 (14)
C4—C5—C6	121.30 (17)	H11—C11—C12	123.430
H5—C5—C6	118.845	S1—C12—C11	112.42 (13)
C5—C6—H6	119.560	S1—C12—H12	123.807
C5—C6—C7	120.21 (16)	C11—C12—H12	123.772
H6—C6—C7	120.233