Crystal structure of 2-tert-butyl-1,3-thia­zolo[4,5-b]pyridine

The title compound, C₁₀H₁₂N₂S, does not contain any strong hydrogen-bond donors but two long C-H...N contacts are observed in the crystal structure, with the most linear inter­action linking mol­ecules along [010]. The ellipsoids of the tert-butyl group indicate large librational motion.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.033
• wR factor = 0.090
• Data-to-parameter ratio = 16.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT242_ALERT_2_C Low       Ueq as Compared to Neighbors for .....         C7 Check
PLAT480_ALERT_4_C Long H...A H-Bond Reported H4     ..  N1      ..       2.81 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H6     ..  N1      ..       2.72 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          8 Why ?
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          2 Note

Alert level G
PLAT033_ALERT_4_G Flack x Value Deviates > 2*sigma from Zero .....      0.027
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         21 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   5 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   2 ALERT level G = General information/check it is not something unexpected

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

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S1. Structural commentary

Various methods have been reported for the synthesis of substituted thia­zolo­pyridines (Smith et al., 1994, 1995; El-Hiti, 2003; Johnson et al., 2006; Rao et al., 2009; Sahasrabudhe et al., 2009; Lee et al., 2010; Chaban et al., 2013). In a continuation of our research focused on new synthetic routes towards substituted heterocycles we have synthesized the title compound 2-tert-butyl­thia­zolo[4,5-b]pyridine in high yield (Smith et al., 1995; El-Hiti, 2003) and now report its X-ray crystal structure. The X-ray structure for a related compound has been reported previously (Yu et al., 2007). In the title compound (Fig. 1), the ellipsoids of the methyl groups of the tert-butyl group are large which is consistent with librational motion of the group. Assumption of a disordered model did not show significant improvement in the refinement. The molecule does not contain strong hydrogen bond donors. In the crystal, two long C—H···N contacts are observed, the most linear of which links the molecules in chains along [010] (Fig. 2).

S2. Synthesis and crystallization

2-tert-Butyl­thia­zolo[4,5-b]pyridine was obtained in 97% yield from acid hydrolysis of 3-(diiso­propyl­amino­thio­carbonyl­thio)-2-(pivalamido)­pyridine under reflux (Smith et al., 1995). The compound may also be synthesized in 66% yield from reaction of 3-(diiso­propyl­amino­thio­carbonyl­thio)-2-amino­pyridine with 2,2-di­methyl­propionic acid in the presence of phospho­rus oxychloride under reflux (El-Hiti, 2003). Crystallization from a mixture of ethyl acetate and di­ethyl ether (1:3 by volume) gave the title compound as colourless crystals. The NMR and low and high resolution mass spectra for the title compound were consistent with those previously reported (Smith et al., 1995).

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in the crystal data table. The hydrogen atoms were positioned geometrically and refined using a riding model with U_iso(H) = 1.2 times U_eq for the atom to which they are bonded in the case of aromatic rings, NH and CH₂ groups and 1.5 times U_eq for the methyl hydrogens. Crystal data, data collection and structure refinement details are summarized in Table 1. The Flack parameter (Parsons et al., 2013) was 0.027 (7) but is not of any structural relevance with this compound.

Related literature

For related structures, see: Smith et al. (1994, 1995); El-Hiti (2003); Johnson et al. (2006); Rao et al. (2009); Sahasrabudhe et al. (2009); Lee et al. (2010); Chaban et al. (2013). For the X-ray crystal structure for a related compound, see: Yu et al. (2007).

Computing details

Data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014; data reduction: CrysAlis PRO (Agilent, 2014; program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008, 2013); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008, 2013); molecular graphics: CHEMDRAW ultra (Cambridge Soft, 2001); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A molecule of the title compound showing atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. Crystal structure packing with the long linear C—H···N contacts shown as dashed lines.

2-tert-Butyl-1,3-thiazolo[4,5-b]pyridine

Crystal data

C10H12N2S	Dx = 1.239 Mg m^−3
Mr = 192.28	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, P212121	Cell parameters from 1951 reflections
a = 9.4606 (3) Å	θ = 6.0–73.4°
b = 9.7999 (3) Å	µ = 2.42 mm^−1
c = 11.1155 (4) Å	T = 296 K
V = 1030.55 (6) Å^3	Plate, colourless
Z = 4	0.40 × 0.29 × 0.14 mm
F(000) = 408

Data collection

Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer	1951 reflections with I > 2σ(I)
Radiation source: SuperNova (Cu) X-ray Source	Rint = 0.016
ω scans	θmax = 73.4°, θmin = 6.0°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −7→11
Tmin = 0.721, Tmax = 1.000	k = −11→12
3395 measured reflections	l = −13→10
1996 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0513P)^2 + 0.0815P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.090	(Δ/σ)max < 0.001
S = 1.12	Δρmax = 0.16 e Å^−3
1996 reflections	Δρmin = −0.22 e Å^−3
121 parameters	Absolute structure: Flack x determined using 791 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013).
0 restraints	Absolute structure parameter: 0.027 (7)

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.

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

	x	y	z	Uiso*/Ueq
C1	0.8245 (2)	0.2846 (2)	0.37042 (19)	0.0458 (5)
C2	0.6967 (2)	0.4685 (2)	0.33748 (19)	0.0435 (5)
C3	0.7716 (2)	0.5154 (3)	0.4378 (2)	0.0483 (5)
C4	0.7455 (3)	0.6454 (3)	0.4822 (3)	0.0645 (6)
H4	0.7924	0.6789	0.5496	0.077*
C5	0.6470 (3)	0.7218 (3)	0.4218 (3)	0.0677 (7)
H5	0.6260	0.8097	0.4477	0.081*
C6	0.5791 (3)	0.6682 (3)	0.3225 (3)	0.0656 (7)
H6	0.5138	0.7234	0.2833	0.079*
C7	0.8831 (3)	0.1417 (2)	0.3577 (2)	0.0556 (6)
C8	0.8599 (5)	0.0641 (4)	0.4747 (3)	0.0938 (11)
H8A	0.9096	0.1090	0.5387	0.141*
H8B	0.8948	−0.0274	0.4662	0.141*
H8C	0.7608	0.0617	0.4929	0.141*
C9	1.0411 (4)	0.1506 (5)	0.3319 (5)	0.1151 (16)
H9A	1.0560	0.1983	0.2575	0.173*
H9B	1.0798	0.0603	0.3260	0.173*
H9C	1.0871	0.1990	0.3961	0.173*
C10	0.8067 (6)	0.0657 (4)	0.2577 (4)	0.124 (2)
H10A	0.7076	0.0614	0.2758	0.186*
H10B	0.8440	−0.0251	0.2513	0.186*
H10C	0.8203	0.1129	0.1829	0.186*
N1	0.72864 (19)	0.3364 (2)	0.30173 (16)	0.0453 (4)
N2	0.6004 (2)	0.5424 (2)	0.2787 (2)	0.0576 (5)
S1	0.88585 (7)	0.39028 (7)	0.48644 (5)	0.0607 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0431 (10)	0.0571 (12)	0.0371 (10)	0.0007 (10)	−0.0013 (8)	0.0016 (9)
C2	0.0423 (10)	0.0483 (11)	0.0398 (10)	−0.0043 (9)	0.0022 (8)	0.0053 (9)
C3	0.0443 (11)	0.0550 (12)	0.0457 (11)	−0.0048 (9)	0.0022 (9)	−0.0035 (9)
C4	0.0664 (15)	0.0611 (14)	0.0661 (15)	−0.0075 (11)	0.0034 (13)	−0.0160 (13)
C5	0.0707 (17)	0.0500 (13)	0.0823 (19)	−0.0008 (12)	0.0129 (15)	−0.0023 (13)
C6	0.0686 (16)	0.0542 (13)	0.0740 (17)	0.0102 (12)	0.0041 (14)	0.0157 (13)
C7	0.0564 (12)	0.0560 (13)	0.0544 (12)	0.0118 (11)	−0.0010 (11)	0.0012 (10)
C8	0.122 (3)	0.078 (2)	0.081 (2)	0.0248 (19)	0.009 (2)	0.0219 (17)
C9	0.074 (2)	0.097 (3)	0.174 (5)	0.0241 (19)	0.044 (3)	−0.007 (3)
C10	0.187 (5)	0.073 (2)	0.112 (3)	0.052 (3)	−0.072 (3)	−0.034 (2)
N1	0.0468 (9)	0.0492 (9)	0.0401 (9)	0.0001 (8)	−0.0045 (8)	0.0005 (8)
N2	0.0588 (11)	0.0570 (11)	0.0570 (12)	0.0070 (10)	−0.0078 (10)	0.0101 (9)
S1	0.0568 (3)	0.0761 (4)	0.0493 (3)	0.0096 (3)	−0.0161 (3)	−0.0112 (3)

Geometric parameters (Å, º)

C1—N1	1.290 (3)	C6—H6	0.9300
C1—C7	1.512 (3)	C7—C10	1.521 (4)
C1—S1	1.753 (2)	C7—C8	1.522 (4)
C2—N2	1.335 (3)	C7—C9	1.524 (4)
C2—N1	1.387 (3)	C8—H8A	0.9600
C2—C3	1.399 (3)	C8—H8B	0.9600
C3—C4	1.389 (4)	C8—H8C	0.9600
C3—S1	1.722 (3)	C9—H9A	0.9600
C4—C5	1.371 (4)	C9—H9B	0.9600
C4—H4	0.9300	C9—H9C	0.9600
C5—C6	1.380 (4)	C10—H10A	0.9600
C5—H5	0.9300	C10—H10B	0.9600
C6—N2	1.341 (4)	C10—H10C	0.9600
N1—C1—C7	124.6 (2)	C8—C7—C9	109.3 (3)
N1—C1—S1	115.80 (18)	C7—C8—H8A	109.5
C7—C1—S1	119.64 (17)	C7—C8—H8B	109.5
N2—C2—N1	121.0 (2)	H8A—C8—H8B	109.5
N2—C2—C3	123.9 (2)	C7—C8—H8C	109.5
N1—C2—C3	115.1 (2)	H8A—C8—H8C	109.5
C4—C3—C2	119.7 (2)	H8B—C8—H8C	109.5
C4—C3—S1	130.8 (2)	C7—C9—H9A	109.5
C2—C3—S1	109.55 (18)	C7—C9—H9B	109.5
C5—C4—C3	116.6 (3)	H9A—C9—H9B	109.5
C5—C4—H4	121.7	C7—C9—H9C	109.5
C3—C4—H4	121.7	H9A—C9—H9C	109.5
C4—C5—C6	120.0 (3)	H9B—C9—H9C	109.5
C4—C5—H5	120.0	C7—C10—H10A	109.5
C6—C5—H5	120.0	C7—C10—H10B	109.5
N2—C6—C5	124.8 (3)	H10A—C10—H10B	109.5
N2—C6—H6	117.6	C7—C10—H10C	109.5
C5—C6—H6	117.6	H10A—C10—H10C	109.5
C1—C7—C10	110.3 (2)	H10B—C10—H10C	109.5
C1—C7—C8	109.3 (2)	C1—N1—C2	110.6 (2)
C10—C7—C8	108.1 (3)	C2—N2—C6	115.0 (2)
C1—C7—C9	108.9 (3)	C3—S1—C1	88.96 (11)
C10—C7—C9	110.9 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···N1^i	0.93	2.81	3.564 (3)	138
C6—H6···N1^ii	0.93	2.72	3.620 (3)	164

Symmetry codes: (i) −x+3/2, −y+1, z+1/2; (ii) −x+1, y+1/2, −z+1/2.