N-[(E)-(5-Methyl­thio­phen-2-yl)methyl­idene]-1H-1,2,4-triazol-3-amine

In the title Schiff base, C₈H₈N₄S, a condensation product of 5-methyl­thio­phene-2-carboxaldehyde and 3-amino-1,2,4-triazole, the dihedral angle between the triazolyl and thienyl rings is 6.44 (14)°. The compound exists as a polymeric chain arising from inter­molecular N—H...N bonding.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.034
• wR factor = 0.097
• Data-to-parameter ratio = 16.5

checkCIF/PLATON results

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Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           28.29
           From the CIF: _reflns_number_total               2206
           Count of symmetry unique reflns         1352
           Completeness (_total/calc)            163.17%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       854
           Fraction of Friedel pairs measured     0.632
           Are heavy atom types Z>Si present        yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   1 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
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Compounds derived from triazole possess antimicrobial, analgesic, anti-inflammatory, local anesthetic, antineoplastic and antimalarial properties (Foroumadi et al., 2003). Some triazole Schiff bases also exhibited antiproliferative and anticancer activity (Manfredini et al., 2000). Due to their significant biological applications they have gained much attention in bioinorganic and metal-based drug discovery. In view of its structural and biological importance, we have synthesized (Chohan et al., 2009), series of triazole derived Schiff bases along with the title compound (I). We report herein, its preperation and crystal structure.

In the molecule of title compound, (Fig 1), the bond lengths and angles are within normal ranges. In this molecule 5-methylthiophen ring is attached to 5-membered ring of triazole moiety through the Schiff bond C=N. The dihedral angle between ring A(S1/C1—C4) and B(C7/N2/N3/C8/N4) is 6.44 (14)°. There exist intramolecular as well as an intermolecular H-bonds as given in Table 1. The molecules are connected to each other through intermolecular H-bonds of N–H···N type in a helical way (Fig 2).

Related literature

For a similar comound, see: Chohan et al. (2009). For the biological properties of such compounds, see: Foroumadi et al. (2003); Manfredini et al. (2000).

S2. Experimental

A mixture of 5-methylthiophene-2-carboxaldehyde (1.09 ml, 0.01 M) and 3-amino-1,2,4-triazole (0.84 g, 0.01 M) in 1:1 molar proportions in methanol (40 ml) was boiled under reflux for 5 h by monitoring through TLC. The reaction mixture was cooled at room temperature and filtered; within an hour a light brown solid product separated from the clear solution. It was filtered, washed with methanol, dried and recrystallized from a mixture of ethanol:methanol (1:1).

S3. Refinement

H-atoms were positioned geometrically, with C—H = 0.96 Å for methyl carbon of thiophene ring and constrained to ride on the parent atom. The coordinates of all other H-atoms were refined. The U_iso(H) = xU_eq(C, N), where x = 1.5 for methyl H and x = 1.2 for all other H atoms.

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999) and PLATON (Spek, 2003)..

Figures

	Fig. 1. ORTEP-3 for Windows (Farrugia, 1997) drawing of the title compound, C8H8N4S, with the atom numbering scheme. The thermal ellipsoids are drawn at the 50% probability level. H-atoms are shown by small circles of arbitrary radii. The intramolecular H-bonding is shown by dashed lines.
	Fig. 2. The partial unit cell packing of (I) (Spek, 2003) showing the interamolecular and intermolecular hydrogen bonding showing that polymeric sheets are formed.

(I)

Crystal data

C8H8N4S	F(000) = 400
Mr = 192.24	Dx = 1.375 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2206 reflections
a = 7.2570 (7) Å	θ = 2.7–28.3°
b = 8.9522 (8) Å	µ = 0.31 mm^−1
c = 14.2930 (15) Å	T = 296 K
V = 928.56 (16) Å^3	Prismatic, light brown
Z = 4	0.24 × 0.16 × 0.14 mm

Data collection

Bruker KAPPA APEXII CCD diffractometer	2206 independent reflections
Radiation source: fine-focus sealed tube	1859 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 7.4 pixels mm^-1	θmax = 28.3°, θmin = 2.7°
ω scans	h = −9→9
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −11→11
Tmin = 0.928, Tmax = 0.956	l = −17→19
5793 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.034	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.097	w = 1/[σ^2(Fo^2) + (0.0562P)^2 + 0.0383P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
2206 reflections	Δρmax = 0.20 e Å^−3
134 parameters	Δρmin = −0.23 e Å^−3
0 restraints	Absolute structure: Flack (1983), 854 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.02 (10)

Special details

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 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	0.48892 (7)	−0.18020 (5)	0.00175 (3)	0.0512 (2)
N1	0.5269 (2)	0.13362 (16)	0.09627 (10)	0.0456 (4)
N2	0.4898 (2)	0.29617 (16)	0.22417 (10)	0.0498 (5)
N3	0.5397 (2)	0.43946 (17)	0.23930 (11)	0.0502 (5)
N4	0.6332 (3)	0.39225 (19)	0.09806 (13)	0.0659 (7)
C1	0.5665 (3)	−0.0136 (2)	−0.04286 (12)	0.0460 (5)
C2	0.6222 (3)	−0.0303 (3)	−0.13344 (14)	0.0565 (7)
C3	0.6008 (3)	−0.1767 (3)	−0.16735 (14)	0.0562 (7)
C4	0.5306 (3)	−0.2720 (2)	−0.10199 (12)	0.0497 (5)
C5	0.4937 (4)	−0.4350 (3)	−0.11161 (16)	0.0737 (9)
C6	0.5724 (3)	0.1226 (2)	0.00957 (13)	0.0473 (5)
C7	0.5491 (3)	0.27297 (19)	0.13780 (12)	0.0432 (5)
C8	0.6228 (3)	0.4940 (3)	0.16478 (17)	0.0654 (8)
H2	0.663 (3)	0.048 (2)	−0.1784 (19)	0.0678*
H3	0.629 (3)	−0.210 (3)	−0.2327 (18)	0.0675*
H3N	0.515 (3)	0.488 (3)	0.2891 (17)	0.0602*
H5A	0.52067	−0.48427	−0.05354	0.1103*
H5B	0.57023	−0.47560	−0.16015	0.1103*
H5C	0.36648	−0.45026	−0.12734	0.1103*
H6	0.621 (3)	0.209 (2)	−0.0237 (15)	0.0567*
H8	0.671 (4)	0.595 (2)	0.1599 (17)	0.0785*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0642 (3)	0.0540 (3)	0.0354 (2)	−0.0070 (2)	0.0078 (2)	−0.0047 (2)
N1	0.0516 (8)	0.0465 (7)	0.0386 (7)	0.0015 (7)	−0.0023 (7)	−0.0011 (6)
N2	0.0668 (10)	0.0434 (7)	0.0392 (7)	0.0024 (7)	0.0000 (8)	0.0002 (5)
N3	0.0644 (10)	0.0439 (8)	0.0422 (8)	0.0024 (7)	−0.0020 (8)	−0.0053 (6)
N4	0.0895 (14)	0.0554 (10)	0.0529 (10)	−0.0181 (9)	0.0184 (10)	−0.0072 (8)
C1	0.0475 (9)	0.0518 (10)	0.0388 (8)	−0.0018 (7)	0.0027 (8)	−0.0017 (7)
C2	0.0641 (13)	0.0637 (13)	0.0418 (10)	−0.0064 (9)	0.0110 (9)	0.0012 (9)
C3	0.0605 (12)	0.0706 (13)	0.0376 (9)	0.0014 (10)	0.0098 (9)	−0.0096 (9)
C4	0.0515 (10)	0.0573 (10)	0.0404 (8)	−0.0008 (8)	0.0011 (8)	−0.0092 (7)
C5	0.100 (2)	0.0629 (12)	0.0582 (12)	−0.0099 (13)	0.0055 (13)	−0.0160 (10)
C6	0.0521 (9)	0.0499 (9)	0.0398 (8)	−0.0004 (8)	−0.0003 (8)	0.0008 (7)
C7	0.0475 (9)	0.0431 (8)	0.0391 (8)	0.0031 (7)	−0.0022 (8)	0.0003 (7)
C8	0.0827 (16)	0.0504 (11)	0.0630 (13)	−0.0152 (11)	0.0126 (12)	−0.0079 (10)

Geometric parameters (Å, º)

S1—C1	1.7169 (19)	C1—C6	1.432 (3)
S1—C4	1.7220 (18)	C2—C3	1.406 (4)
N1—C6	1.286 (2)	C3—C4	1.364 (3)
N1—C7	1.391 (2)	C4—C5	1.490 (3)
N2—N3	1.350 (2)	C2—H2	1.00 (2)
N2—C7	1.324 (2)	C3—H3	1.00 (3)
N3—C8	1.318 (3)	C5—H5A	0.9600
N4—C7	1.355 (3)	C5—H5B	0.9600
N4—C8	1.321 (3)	C5—H5C	0.9600
N3—H3N	0.85 (3)	C6—H6	0.974 (19)
C1—C2	1.365 (3)	C8—H8	0.97 (2)
S1···N1	3.1295 (15)	N4···H5A^vii	2.5700
S1···C4^i	3.647 (2)	N4···H6	2.39 (2)
N1···S1	3.1295 (15)	C1···N4^v	3.419 (3)
N1···N3^ii	2.963 (2)	C4···S1^viii	3.647 (2)
N2···N4	2.252 (2)	C8···N2^iii	3.241 (3)
N2···C8^ii	3.241 (3)	C7···H3^vi	3.03 (2)
N2···N3^ii	3.243 (2)	C7···H3N^ii	2.80 (3)
N3···N1^iii	2.963 (2)	H2···N2^iv	2.83 (2)
N3···N4	2.171 (2)	H2···N3^iv	2.87 (2)
N3···N2^iii	3.243 (2)	H3···N2^ix	2.94 (2)
N4···C1^iv	3.419 (3)	H3···C7^ix	3.03 (2)
N4···N3	2.171 (2)	H3N···N1^iii	2.12 (3)
N1···H3N^ii	2.12 (3)	H3N···N2^iii	2.77 (3)
N2···H8^ii	2.71 (2)	H3N···C7^iii	2.80 (3)
N2···H2^v	2.83 (2)	H5A···N4^x	2.5700
N2···H3^vi	2.94 (2)	H6···N4	2.39 (2)
N2···H3N^ii	2.77 (3)	H8···N2^iii	2.71 (2)
N3···H2^v	2.87 (2)
C1—S1—C4	92.13 (9)	N1—C7—N4	125.46 (16)
C6—N1—C7	116.76 (15)	N2—C7—N4	114.44 (16)
N3—N2—C7	102.19 (14)	N3—C8—N4	110.7 (2)
N2—N3—C8	110.20 (17)	C1—C2—H2	128.6 (14)
C7—N4—C8	102.42 (18)	C3—C2—H2	117.8 (14)
C8—N3—H3N	125.6 (17)	C2—C3—H3	125.2 (15)
N2—N3—H3N	124.1 (17)	C4—C3—H3	121.9 (15)
S1—C1—C6	123.72 (14)	C4—C5—H5A	109.00
C2—C1—C6	125.52 (19)	C4—C5—H5B	109.00
S1—C1—C2	110.75 (16)	C4—C5—H5C	110.00
C1—C2—C3	113.4 (2)	H5A—C5—H5B	109.00
C2—C3—C4	112.85 (18)	H5A—C5—H5C	109.00
S1—C4—C3	110.91 (15)	H5B—C5—H5C	109.00
C3—C4—C5	128.07 (19)	N1—C6—H6	120.2 (12)
S1—C4—C5	121.02 (15)	C1—C6—H6	115.6 (12)
N1—C6—C1	124.19 (17)	N3—C8—H8	124.6 (15)
N1—C7—N2	120.07 (16)	N4—C8—H8	124.7 (15)
C1—S1—C4—C3	−0.12 (18)	C8—N4—C7—N2	−0.4 (3)
C4—S1—C1—C2	−0.28 (18)	C7—N4—C8—N3	0.4 (2)
C4—S1—C1—C6	−179.69 (19)	C8—N4—C7—N1	−178.6 (2)
C1—S1—C4—C5	178.8 (2)	C2—C1—C6—N1	−176.6 (2)
C6—N1—C7—N4	−7.9 (3)	S1—C1—C2—C3	0.6 (2)
C7—N1—C6—C1	177.03 (19)	C6—C1—C2—C3	−180.0 (2)
C6—N1—C7—N2	173.91 (18)	S1—C1—C6—N1	2.7 (3)
C7—N2—N3—C8	0.1 (2)	C1—C2—C3—C4	−0.7 (3)
N3—N2—C7—N1	178.54 (17)	C2—C3—C4—S1	0.5 (2)
N3—N2—C7—N4	0.2 (2)	C2—C3—C4—C5	−178.4 (2)
N2—N3—C8—N4	−0.3 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3n···N1^iii	0.85 (3)	2.12 (3)	2.963 (2)	172 (2)
C6—H6···N4	0.974 (19)	2.39 (2)	2.761 (3)	101.7 (15)

Symmetry code: (iii) −x+1, y+1/2, −z+1/2.