2-Amino-4-methyl­thio­phene-3-carbo­nitrile

The title compound, C₆H₆N₂S, consists of a thio­phene ring carrying three substitutent groups. Two N—H...N intermolec­ular hydrogen bonds link neighboring mol­ecules into a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.052
• wR factor = 0.154
• Data-to-parameter ratio = 13.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

---

S1. Comment

Highly substituted thiophenes form an important part of numerous natural products (Koike et al., 1997) and pharmaceuticals (World Drug Index, 2000). They are often used as novel conducting polymers and isostatic replacements for phenyl groups in medicinal chemistry (Jarvest et al., 1999). The electronic and optical properties of polythiophene and its derivatives have been the subject of many investigations (Roncali, 1997; Ekinci et al., 2002).

The title compound, (II) (Fig. 1), consists of a thiophene ring carrying three subtituents, viz. an amino group, a methyl group and a cyano group. The S—C bond lengths, 1.728 (4) and 1.725 (4) Å, are in good agreement with those in the literature, e.g. 1.734 (2) and 1.721 (3) Å (Han & Choi, 2000), 1.727 (1) and 1.729 (2) Å (Elerman & Elmalı, 1998), and 1.723 (2) and 1.735 (3) Å (Wouters et al., 1997). The C1≡N1 bond distance is 1.153 (4) Å, typical of such a triple bond. This value agrees well with similar bonds reported in the literature, e.g. 1.132 (2) Å (Elerman et al., 1998), 1.130 (5) and 1.142 (5) Å (Çoruh et al., 2002), and 1.148 (2) Å (Boitsov et al., 2002). The molecule of (II) is planar, the maximum deviation from the least-squares plane being 0.0074 (33) Å for atom C4.

A packing diagram of (II) is shown Fig.2. The molecules are stacked such that there are no ring–ring or X—H···π interactions between molecules in the stacks; the distance between planes of molecules in the stacks is 5.671 (7) Å. The crystal structure of (II) is stabilized by two N—H···N intermolecular hydrogen bonds (Table 3 and Fig. 2).

S2. Experimental

2-(2-Bromo-1-methylethylidene)malononitrile (0.94 g, 5 mmol) was dissolved in a solution of dioxane (5 ml) and absolute ethanol (20 ml). The stirred solution was cooled to 273 K in an ice-salt bath, and a suspension of NaSH (0.3 g) in 10 ml of absolute ethanol was then added dropwise over a period of 30 min. The resulting reaction mixture was stirred for a further 1 h at room temperature. After removal of the solvent, the residue was filtered on a short Al₂O₃ column, eluting with hexane-ethyl acetate (7:3). The solvent was removed and the residue crystallized from chloroform to yield (556 mg, 81%) 2-amino-4-methylthiophene-3-carbonitrile (light pink crystals, mp 391–392 K). ¹H NMR (200 MHz, CDCl₃): δ 5.59 (s, 1H, H₅), 4.81 (bs, 2H, NH₂), 2.11 (s, 3H, CH₃); ¹³C NMR (50 MHz, CDCl₃) δ 162.44, 135.91, 115.52, 105.32, 91.03, 15.53. IR (CHCl₃) 3417, 3212, 3097, 2977, 2202, 1627, 1558, 1446, 1300, 1191, 1068, 836.

S3. Refinement

All H atoms were positioned geometrically and refined in riding mode, with methyl C—H = 0.96 Å, other C—H = 0.93 Å, and N—H = 0.86 Å. For methyl H, U_iso values were set equal to 1.5U_eq of the carrier C atom. For other C—H and N—H, U_iso(H) values were set equal to 1.2U_eq of the carrier atom.

Computing details

Data collection: COLLECT (Nonius BV, 1997-2000); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 1997); software used to prepare material for publication: SHELXL97 and WinGX (Farrugia, 1999).

Figures

	Fig. 1. View of the title compound, with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.
	Fig. 2. The hydrogen-bond network in (II), viewed approximately along the [010] direction. Hydrogen bonds are indicated by dashed lines.

2-Amino-4-methyl-thiophene-3-carbonitrile

Crystal data

C6H6N2S	F(000) = 288
Mr = 138.20	Dx = 1.376 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 1153 reflections
a = 11.900 (5) Å	θ = 1.8–25.2°
b = 4.130 (5) Å	µ = 0.39 mm^−1
c = 14.085 (5) Å	T = 293 K
β = 105.562 (5)°	Block, pink
V = 666.9 (9) Å^3	0.20 × 0.15 × 0.10 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	789 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.060
Graphite monochromator	θmax = 25.2°, θmin = 1.8°
Detector resolution: 9.0 pixels mm^-1	h = −13→13
φ and ω scans	k = −4→4
1849 measured reflections	l = −16→16
1135 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.154	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.087P)^2] where P = (Fo^2 + 2Fc^2)/3
1135 reflections	(Δ/σ)max < 0.001
82 parameters	Δρmax = 0.33 e Å^−3
0 restraints	Δρmin = −0.31 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'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 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 > σ(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.

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

	x	y	z	Uiso*/Ueq
S1	0.22387 (8)	0.4859 (2)	0.19442 (6)	0.0548 (4)
N1	0.4040 (3)	0.2476 (9)	0.5560 (2)	0.0705 (13)
N2	0.4211 (2)	0.1820 (7)	0.29110 (19)	0.0569 (10)
C1	0.3527 (3)	0.3217 (9)	0.4774 (2)	0.0492 (11)
C4	0.3236 (3)	0.3380 (8)	0.2982 (2)	0.0443 (11)
C5	0.2886 (3)	0.4118 (8)	0.3817 (2)	0.0438 (10)
C6	0.1794 (3)	0.5838 (8)	0.3609 (2)	0.0476 (11)
C7	0.1362 (3)	0.6384 (9)	0.2635 (2)	0.0569 (12)
C9	0.1231 (3)	0.6872 (10)	0.4390 (3)	0.0666 (14)
H2A	0.47107	0.11444	0.34343	0.0682*
H2B	0.43302	0.15043	0.23424	0.0682*
H7	0.06649	0.74689	0.23638	0.0682*
H9A	0.17089	0.62150	0.50243	0.0995*
H9B	0.04766	0.58798	0.42726	0.0995*
H9C	0.11467	0.91846	0.43761	0.0995*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0595 (7)	0.0625 (7)	0.0379 (5)	0.0033 (4)	0.0054 (4)	0.0032 (4)
N1	0.067 (2)	0.096 (3)	0.0456 (18)	0.0009 (19)	0.0099 (15)	0.0109 (17)
N2	0.0566 (18)	0.069 (2)	0.0454 (15)	0.0089 (17)	0.0140 (13)	0.0038 (14)
C1	0.0479 (19)	0.056 (2)	0.0443 (19)	−0.0050 (17)	0.0132 (15)	−0.0022 (16)
C4	0.0470 (19)	0.0425 (19)	0.0425 (17)	−0.0048 (16)	0.0105 (14)	0.0021 (14)
C5	0.0454 (18)	0.0456 (19)	0.0388 (17)	−0.0067 (15)	0.0084 (14)	0.0013 (14)
C6	0.0461 (19)	0.049 (2)	0.0462 (19)	−0.0053 (16)	0.0096 (15)	−0.0031 (15)
C7	0.051 (2)	0.059 (2)	0.055 (2)	0.0052 (18)	0.0042 (16)	0.0027 (18)
C9	0.063 (2)	0.076 (3)	0.064 (2)	0.005 (2)	0.0226 (18)	−0.006 (2)

Geometric parameters (Å, º)

S1—C4	1.728 (4)	C5—C6	1.440 (5)
S1—C7	1.725 (4)	C6—C9	1.496 (5)
N1—C1	1.153 (4)	C6—C7	1.349 (4)
N2—C4	1.354 (5)	C7—H7	0.9299
N2—H2B	0.8599	C9—H9A	0.9605
N2—H2A	0.8600	C9—H9B	0.9600
C1—C5	1.409 (4)	C9—H9C	0.9600
C4—C5	1.383 (5)
S1···N1^i	3.401 (5)	C1···H2A	2.7756
S1···H9A^ii	3.0699	C1···H9A	2.5976
N1···N2^iii	3.117 (6)	C7···H7^vii	2.9042
N1···S1^iv	3.401 (5)	H2A···C1	2.7756
N1···N2^iv	3.276 (5)	H2A···N1^iii	2.3070
N2···N1^i	3.276 (5)	H2B···N2^v	2.6863
N2···N2^v	3.209 (5)	H2B···N2^vi	2.8798
N2···N2^vi	3.209 (5)	H2B···H2B^v	2.5735
N2···N1^iii	3.117 (6)	H2B···H2B^vi	2.5735
N1···H2A^iii	2.3071	H2B···N1^i	2.4767
N1···H2B^iv	2.4767	H7···C7^viii	2.9042
N2···H2B^vi	2.6863	H9A···C1	2.5976
N2···H2B^v	2.8798	H9A···S1^ix	3.0699
C4—S1—C7	91.95 (15)	C5—C6—C9	123.3 (3)
H2A—N2—H2B	120.01	C7—C6—C9	125.2 (3)
C4—N2—H2A	120.02	S1—C7—C6	112.9 (3)
C4—N2—H2B	119.98	S1—C7—H7	123.50
N1—C1—C5	179.2 (4)	C6—C7—H7	123.57
S1—C4—N2	120.9 (2)	C6—C9—H9A	109.46
S1—C4—C5	110.3 (3)	C6—C9—H9B	109.52
N2—C4—C5	128.8 (3)	C6—C9—H9C	109.52
C4—C5—C6	113.4 (3)	H9A—C9—H9B	109.43
C1—C5—C4	123.1 (3)	H9A—C9—H9C	109.42
C1—C5—C6	123.5 (3)	H9B—C9—H9C	109.48
C5—C6—C7	111.5 (3)
C7—S1—C4—N2	−179.3 (3)	C1—C5—C6—C7	−179.7 (3)
C7—S1—C4—C5	−0.8 (3)	C1—C5—C6—C9	0.5 (5)
C4—S1—C7—C6	0.3 (3)	C4—C5—C6—C9	179.4 (3)
S1—C4—C5—C6	1.1 (4)	C4—C5—C6—C7	−0.8 (4)
N2—C4—C5—C1	−1.7 (6)	C9—C6—C7—S1	180.0 (3)
S1—C4—C5—C1	179.9 (3)	C5—C6—C7—S1	0.2 (4)
N2—C4—C5—C6	179.4 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2B···N1^i	0.86	2.48	3.276 (5)	155
N2—H2A···N1^iii	0.86	2.31	3.117 (6)	157

Symmetry codes: (i) x, −y+1/2, z−1/2; (iii) −x+1, −y, −z+1.