N-[(5-Chloro­thio­phen-2-yl)methyl­ene]-5-methyl­thia­zol-2-amine

The molecule of the title compound, a Schiff base, C₉H₇ClN₂S₂, is roughly planar, with the two rings twisted by only 8.8°. Mol­ecules are inter­connected by weak C—H...S inter­actions leading to the formation of chains parallel to the c axis. Weak slipped π–π stacking between the thio­phene rings may help in further stabilizing the packing (centroid-to-centroid distance = 3.947 Å, inter­planar distance = 3.651 Å and offset angle = 22.3°).

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.022
• wR factor = 0.060
• Data-to-parameter ratio = 14.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT322_ALERT_2_C Check Hybridisation of  S2     in Main Residue .          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H5     ..  S2      ..       2.97 Ang.

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           25.20
           From the CIF: _reflns_number_total               1839
           Count of symmetry unique reflns         1003
           Completeness (_total/calc)            183.35%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       836
           Fraction of Friedel pairs measured     0.833
           Are heavy atom types Z>Si present        yes
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

   0 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
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Schiff base ligands have significant importance in chemistry, especially in the development of Schiff base complexes, (Johnson et al., 1996; Alizadeh et al.,1999; Wang & Zheng, 2007). Schiff bases that have solvent-dependent UV/vis spectra (solvatochromicity) can be suitable NLO (nonlinear optically active) materials (Alemi & Shaabani, 2000). They are also useful in the asymmetric oxidation of methyl phenyl sulfide and are enantioselective (Kim & Shin, 1999). In this paper, we report the synthesis and crystal structure of the title compound, (I).

The title compound is roughly planar with the two thiophene rings twisted by only (Fig. 1). The bond lengths and bond angles are usual for such compounds. The crystal packing is governed by weak C—H···S interactions (Table 1) forming chains parallel to the c axis and very weak slipped π–π stacking between the thiophene rings with centroid to centroid distance of 3.947 Å and interplanar distance of 3.651 Å resulting in an offset angle of 22.3°.

Related literature

For related literature, see: Alemi & Shaabani (2000); Alizadeh et al. (1999); Johnson et al. (1996); Kim & Shin (1999); Wang & Zheng (2007). [Please provide revised scheme with the second S atom shown.]

S2. Experimental

Under nitrogen, a mixture of 5-chlorothiophene-2-carbaldehyde (1.67 g,10 mmol), Na₂SO₄ (3.0 g) and 5-methylthiazol-2-amine (1.58 g, 10 mmol) in absolute ethanol (20 ml) was refluxed for about 12 h to yield a yellow precipitate. The product was collected by vacuum filtration and washed with ethanol. The crude solid was redissolved in CH₂Cl₂ (100 ml) and washed with water (2 x 15 ml) and brine (8 ml). After drying over Na₂SO₄, the solvent was removed under vacuum, and a yellow solid was isolated in 92% yield (3.1 g). Colourless single crystals of the Schiff base, (I), suitable for X-ray analysis were grown from CH₂Cl₂ and absolute ethanol (4:1) by slow evaporation of the solvents at room temperature over a period of about one week.

S3. Refinement

All H atoms were fixed geometrically and treated as riding with C—H = 0.93 Å (aromatic) or 0.98 Å (methyl) with U_iso(H) = xU_eq(C) where x = 1.2 for aromatic H and 1.5 for methyl H.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The molecular structure of (I), showing the atomic numbering scheme. Probability displacement ellipsoids are drawn at the 30% level.

N-[(5-Chlorothiophen-2-yl)methylene]-5-methylthiazol-2-amine

Crystal data

C9H7ClN2S2	F(000) = 248
Mr = 242.74	Dx = 1.499 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1839 reflections
a = 3.9472 (4) Å	θ = 3.5–25.2°
b = 23.281 (2) Å	µ = 0.70 mm^−1
c = 6.0379 (6) Å	T = 298 K
β = 104.214 (1)°	Block, colourless
V = 537.87 (9) Å^3	0.31 × 0.25 × 0.19 mm
Z = 2

Data collection

Bruker APEX area-detector diffractometer	1839 independent reflections
Radiation source: fine-focus sealed tube	1766 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
φ and ω scans	θmax = 25.2°, θmin = 3.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −4→4
Tmin = 0.812, Tmax = 0.878	k = −24→27
3269 measured reflections	l = −7→7

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)] = 0.022	H-atom parameters constrained
wR(F^2) = 0.060	w = 1/[σ^2(Fo^2) + (0.0362P)^2 + 0.0225P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
1839 reflections	Δρmax = 0.18 e Å^−3
128 parameters	Δρmin = −0.12 e Å^−3
1 restraint	Absolute structure: Flack (1983), with 836 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (6)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 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
C1	1.4257 (6)	0.94947 (11)	1.1100 (4)	0.0662 (6)
H1A	1.5326	0.9797	1.0429	0.099*
H1B	1.5992	0.9311	1.2282	0.099*
H1C	1.2463	0.9653	1.1742	0.099*
C2	1.2681 (5)	0.90636 (10)	0.9303 (4)	0.0501 (4)
C3	1.2361 (6)	0.90871 (10)	0.7032 (4)	0.0564 (5)
H3	1.3129	0.9405	0.6359	0.068*
C4	1.0034 (5)	0.82366 (9)	0.7061 (3)	0.0469 (4)
C5	0.7404 (5)	0.75947 (9)	0.4337 (4)	0.0491 (4)
H5	0.7667	0.7873	0.3286	0.059*
C6	0.5772 (5)	0.70562 (9)	0.3507 (4)	0.0486 (5)
C7	0.4437 (7)	0.68890 (11)	0.1310 (4)	0.0634 (6)
H7	0.4465	0.7120	0.0059	0.076*
C8	0.3010 (6)	0.63335 (11)	0.1111 (4)	0.0657 (6)
H8	0.1995	0.6156	−0.0274	0.079*
C9	0.3287 (5)	0.60889 (9)	0.3165 (4)	0.0542 (5)
Cl1	0.18698 (18)	0.54193 (3)	0.36876 (14)	0.0784 (2)
N1	0.8487 (4)	0.77019 (7)	0.6444 (3)	0.0496 (4)
N2	1.0867 (5)	0.86277 (8)	0.5751 (3)	0.0559 (4)
S1	0.52770 (13)	0.65240 (2)	0.53993 (8)	0.05352 (14)
S2	1.10583 (13)	0.84148 (2)	0.99287 (8)	0.05410 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0655 (13)	0.0622 (16)	0.0671 (14)	−0.0105 (11)	0.0090 (11)	−0.0118 (11)
C2	0.0461 (9)	0.0458 (11)	0.0565 (11)	0.0005 (9)	0.0092 (8)	−0.0018 (9)
C3	0.0657 (12)	0.0436 (11)	0.0586 (12)	−0.0054 (10)	0.0127 (10)	0.0040 (9)
C4	0.0496 (10)	0.0436 (11)	0.0476 (10)	0.0025 (8)	0.0120 (8)	0.0017 (8)
C5	0.0520 (10)	0.0441 (11)	0.0520 (11)	0.0007 (8)	0.0139 (8)	0.0065 (8)
C6	0.0501 (10)	0.0447 (12)	0.0503 (11)	0.0024 (8)	0.0113 (8)	0.0041 (8)
C7	0.0821 (14)	0.0542 (14)	0.0505 (12)	−0.0005 (11)	0.0095 (11)	0.0023 (10)
C8	0.0766 (15)	0.0574 (15)	0.0548 (12)	−0.0005 (10)	0.0001 (10)	−0.0081 (10)
C9	0.0478 (10)	0.0431 (11)	0.0702 (13)	0.0012 (8)	0.0118 (9)	−0.0054 (9)
Cl1	0.0752 (4)	0.0445 (3)	0.1166 (5)	−0.0065 (3)	0.0253 (3)	0.0009 (3)
N1	0.0539 (9)	0.0418 (10)	0.0522 (10)	−0.0004 (7)	0.0114 (7)	0.0020 (7)
N2	0.0713 (11)	0.0466 (11)	0.0492 (9)	−0.0048 (8)	0.0134 (8)	0.0021 (7)
S1	0.0612 (3)	0.0480 (3)	0.0502 (3)	−0.0033 (2)	0.0115 (2)	0.0039 (2)
S2	0.0625 (3)	0.0525 (3)	0.0464 (2)	−0.0058 (2)	0.0117 (2)	0.0024 (2)

Geometric parameters (Å, º)

C1—C2	1.496 (3)	C5—N1	1.264 (3)
C1—H1A	0.9600	C5—C6	1.442 (3)
C1—H1B	0.9600	C5—H5	0.9300
C1—H1C	0.9600	C6—C7	1.358 (3)
C2—C3	1.347 (3)	C6—S1	1.729 (2)
C2—S2	1.719 (2)	C7—C8	1.404 (4)
C3—N2	1.366 (3)	C7—H7	0.9300
C3—H3	0.9300	C8—C9	1.345 (3)
C4—N2	1.300 (3)	C8—H8	0.9300
C4—N1	1.396 (3)	C9—Cl1	1.712 (2)
C4—S2	1.729 (2)	C9—S1	1.715 (2)
C2—C1—H1A	109.5	C6—C5—H5	118.9
C2—C1—H1B	109.5	C7—C6—C5	128.4 (2)
H1A—C1—H1B	109.5	C7—C6—S1	111.11 (17)
C2—C1—H1C	109.5	C5—C6—S1	120.45 (16)
H1A—C1—H1C	109.5	C6—C7—C8	113.5 (2)
H1B—C1—H1C	109.5	C6—C7—H7	123.2
C3—C2—C1	129.0 (2)	C8—C7—H7	123.2
C3—C2—S2	108.21 (16)	C9—C8—C7	111.8 (2)
C1—C2—S2	122.77 (17)	C9—C8—H8	124.1
C2—C3—N2	117.6 (2)	C7—C8—H8	124.1
C2—C3—H3	121.2	C8—C9—Cl1	126.84 (18)
N2—C3—H3	121.2	C8—C9—S1	113.16 (17)
N2—C4—N1	128.43 (19)	Cl1—C9—S1	120.00 (14)
N2—C4—S2	114.16 (15)	C5—N1—C4	117.54 (17)
N1—C4—S2	117.41 (14)	C4—N2—C3	110.04 (18)
N1—C5—C6	122.24 (18)	C9—S1—C6	90.44 (11)
N1—C5—H5	118.9	C2—S2—C4	89.94 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···S2^i	0.93	2.97	3.834 (2)	155

Symmetry code: (i) x, y, z−1.