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

The title compound, C₉H₇BrN₂S₂, is a Schiff base. There is an intra­molecular hydrogen bond which stabilizes the structure. The mol­ecules are further assembled into a supra­molecular network via weak C—H...N inter­molecular hydrogen bonds and π–π inter­actions with a distance of 3.15 Å between the thiophene rings.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.034
• wR factor = 0.084
• Data-to-parameter ratio = 16.4

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.922     0.938
            Tmin and Tmax expected:      0.348     0.404
            RR =      1.140
            Please check that your absorption correction is appropriate.
PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.13
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.43
PLAT322_ALERT_2_C Check Hybridisation of  S2     in Main Residue .          ?
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  N1      ..       3.19 Ang.

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.431
            Tmax scaled      0.404 Tmin scaled      0.397

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 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
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 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

Schiff base ligands have significant importance in chemistry, specially in the development of Schiff base complexes, because Schiff base ligands are potentially capable of forming stable complexes with metal ions (Johnson et al., 1996; Alizadeh et al., 1999). Schiff bases that have solvent dependent UV/vis spectra (solvatochromicity) can be suitable NLO (nonlinear optical active) materials (Alemi et al., 2000). They are also useful in asymmetric oxidation of methyl phenyl sulfide and enantioselective (Kim et al., 1999). In this paper, we report the synthesis and crystal structure of the title compound (I).

The molecular structure of the title compound (Fig. 1) contains one intramolecular hydrogen bonds [C5—H5\···S2](Table 1). The C5—N1 bond lengths is 1.277 (3) Å, indicative of standard C=N double bond. The other C—N, C—S and C—C distances show no remarkable features. A supramolecular network is formed by C—H···N intermolecular hydrogen bonding and weak π-π interactions. The centroid-to-centroid and interplanar distances between adjacent rings (Symmetry code: 1 - x, 2 - y, -z) are 3.712 (4) and 3.556 (3) Å, respectively.

Related literature

For general background, see: Johnson et al., 1996; Alizadeh et al., 1999; Alemi et al., 2000; Kim et al., 1999.

S2. Experimental

Under nitrogen, a mixture of 5-methylthiazol-2-amine (1.63 g,8 mmol), Na₂SO₄ (3.0 g) and 5-bromo-2-thiophenecarboxaldehyde(1.52 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*10 ml)and brine(10 ml). After dried over Na₂SO₄, the solvent was removed under vacuum, and yellow solid was isolated in yield 92% (3.1 g). Yellow single crystals of the compound suitable for X-ray analysis were grown from CH₂Cl₂ and absolute ethanol(4:1) by slow evaporation of the solvent at room temperature over a period of about a week.

S3. Refinement

All H atoms were placed in calculated positions, C—H = 0.93Å (C_aromatic) or 0.96 Å (CH₃) and treated as riding on their parent atoms, with U_iso(H) =1.2U_eq(C_aromatic) and U_iso(H) = 1.5U_eq(CH₃).

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 structure of (I), showing the atomic numbering scheme. Non-H atoms are shown as 50% probability displacement ellipsoids.

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

Crystal data

C9H7BrN2S2	F(000) = 568
Mr = 287.20	Dx = 1.753 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2100 reflections
a = 9.5515 (10) Å	θ = 1.7–28.0°
b = 10.9177 (11) Å	µ = 4.12 mm^−1
c = 10.9141 (11) Å	T = 298 K
β = 107.06 (10)°	Block, colourless
V = 1088.03 (19) Å^3	0.36 × 0.22 × 0.22 mm
Z = 4

Data collection

Bruker APEXII area-detector diffractometer	2096 independent reflections
Radiation source: fine-focus sealed tube	1622 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.067
φ and ω scans	θmax = 26.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.922, Tmax = 0.938	k = −12→13
6883 measured reflections	l = −13→13

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.084	H-atom parameters constrained
S = 0.94	w = 1/[σ^2(Fo^2) + (0.0459P)^2] where P = (Fo^2 + 2Fc^2)/3
2096 reflections	(Δ/σ)max < 0.001
128 parameters	Δρmax = 0.73 e Å^−3
0 restraints	Δρmin = −0.53 e Å^−3

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
Br1	0.59314 (4)	1.23977 (3)	0.17687 (4)	0.06274 (16)
C1	0.4366 (3)	1.1433 (3)	0.0801 (3)	0.0458 (7)
C2	0.3745 (3)	1.1446 (3)	−0.0481 (3)	0.0527 (8)
H2	0.4021	1.1968	−0.1042	0.063*
C3	0.2627 (3)	1.0568 (3)	−0.0855 (3)	0.0520 (7)
H3	0.2081	1.0445	−0.1704	0.062*
C4	0.2416 (3)	0.9918 (3)	0.0131 (3)	0.0432 (7)
C5	0.1400 (3)	0.8926 (3)	0.0063 (3)	0.0453 (7)
H5	0.0812	0.8673	−0.0737	0.054*
C6	0.0274 (3)	0.7426 (2)	0.0921 (3)	0.0401 (6)
C7	−0.0887 (3)	0.5910 (3)	0.1508 (3)	0.0568 (8)
H7	−0.1098	0.5375	0.2094	0.068*
C8	−0.1607 (3)	0.5841 (3)	0.0254 (3)	0.0462 (7)
C9	−0.2806 (4)	0.4988 (3)	−0.0419 (3)	0.0684 (9)
H9A	−0.2957	0.4395	0.0179	0.103*
H9B	−0.2541	0.4577	−0.1096	0.103*
H9C	−0.3692	0.5444	−0.0773	0.103*
N1	0.1279 (2)	0.8383 (2)	0.1063 (2)	0.0426 (5)
N2	0.0168 (3)	0.6793 (3)	0.1898 (2)	0.0547 (7)
S1	0.36114 (8)	1.03825 (6)	0.15710 (7)	0.0455 (2)
S2	−0.09293 (8)	0.69442 (7)	−0.05398 (7)	0.0467 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0652 (3)	0.0450 (2)	0.0753 (3)	−0.01064 (14)	0.0164 (2)	−0.00415 (16)
C1	0.0477 (17)	0.0379 (16)	0.0550 (19)	0.0027 (12)	0.0202 (15)	0.0012 (13)
C2	0.064 (2)	0.0484 (18)	0.0535 (19)	0.0008 (15)	0.0297 (17)	0.0066 (15)
C3	0.0604 (19)	0.0592 (19)	0.0378 (16)	−0.0002 (15)	0.0167 (14)	−0.0006 (14)
C4	0.0431 (16)	0.0445 (16)	0.0416 (15)	0.0041 (12)	0.0118 (13)	−0.0020 (13)
C5	0.0427 (16)	0.0500 (18)	0.0411 (17)	0.0009 (13)	0.0093 (14)	−0.0054 (14)
C6	0.0403 (15)	0.0451 (17)	0.0348 (15)	0.0055 (12)	0.0107 (12)	−0.0012 (12)
C7	0.0583 (19)	0.066 (2)	0.052 (2)	−0.0056 (16)	0.0244 (16)	0.0121 (16)
C8	0.0475 (16)	0.0448 (17)	0.0487 (18)	0.0023 (13)	0.0177 (15)	−0.0004 (13)
C9	0.068 (2)	0.062 (2)	0.074 (2)	−0.0127 (17)	0.0188 (19)	−0.0009 (18)
N1	0.0442 (13)	0.0475 (14)	0.0360 (13)	−0.0008 (10)	0.0115 (11)	−0.0016 (11)
N2	0.0578 (16)	0.0718 (18)	0.0350 (14)	−0.0071 (14)	0.0144 (12)	0.0068 (13)
S1	0.0506 (4)	0.0430 (4)	0.0410 (4)	−0.0008 (3)	0.0105 (3)	0.0022 (3)
S2	0.0559 (5)	0.0444 (4)	0.0360 (4)	−0.0034 (3)	0.0074 (3)	0.0011 (3)

Geometric parameters (Å, º)

Br1—C1	1.880 (3)	C6—N2	1.299 (4)
C1—C2	1.350 (4)	C6—N1	1.397 (3)
C1—S1	1.702 (3)	C6—S2	1.750 (3)
C2—C3	1.403 (4)	C7—C8	1.342 (4)
C2—H2	0.9300	C7—N2	1.370 (4)
C3—C4	1.353 (4)	C7—H7	0.9300
C3—H3	0.9300	C8—C9	1.491 (4)
C4—C5	1.442 (4)	C8—S2	1.718 (3)
C4—S1	1.725 (3)	C9—H9A	0.9600
C5—N1	1.277 (3)	C9—H9B	0.9600
C5—H5	0.9300	C9—H9C	0.9600
C2—C1—S1	113.4 (2)	N1—C6—S2	124.9 (2)
C2—C1—Br1	127.7 (2)	C8—C7—N2	117.8 (3)
S1—C1—Br1	118.84 (17)	C8—C7—H7	121.1
C1—C2—C3	111.1 (3)	N2—C7—H7	121.1
C1—C2—H2	124.5	C7—C8—C9	128.8 (3)
C3—C2—H2	124.5	C7—C8—S2	108.6 (2)
C4—C3—C2	113.9 (3)	C9—C8—S2	122.6 (2)
C4—C3—H3	123.1	C8—C9—H9A	109.5
C2—C3—H3	123.1	C8—C9—H9B	109.5
C3—C4—C5	127.5 (3)	H9A—C9—H9B	109.5
C3—C4—S1	110.9 (2)	C8—C9—H9C	109.5
C5—C4—S1	121.6 (2)	H9A—C9—H9C	109.5
N1—C5—C4	122.2 (3)	H9B—C9—H9C	109.5
N1—C5—H5	118.9	C5—N1—C6	119.0 (3)
C4—C5—H5	118.9	C6—N2—C7	110.3 (3)
N2—C6—N1	121.6 (3)	C1—S1—C4	90.63 (14)
N2—C6—S2	113.6 (2)	C8—S2—C6	89.72 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···S2	0.93	2.57	3.034 (3)	112
C5—H5···N2^i	0.93	2.52	3.398 (4)	157

Symmetry code: (i) x, −y+3/2, z−1/2.