Crystal structure of 3-[2-(1,3-thia­zol-2-yl)diazen-1-yl]pyridine-2,6-di­amine monohydrate

Chotima, R.; Boonseng, B.; Piyasaengthong, A.; Songsasen, A.; Chainok, K.

doi:10.1107/S2056989018004693

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ISSN: 2056-9890

Volume 74| Part 4| April 2018| Pages 563-565

https://doi.org/10.1107/S2056989018004693

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Crystal structure of 3-[2-(1,3-thiazol-2-yl)diazen-1-yl]pyridine-2,6-diamine monohydrate

Ratanon Chotima,^a ^* Bussaba Boonseng,^a Akkharadet Piyasaengthong,^b Apisit Songsasen ^b and Kittipong Chainok ^c

^aDepartment of Chemistry, Faculty of Science, Naresuan University, Muang, Phitsanulok 65000, Thailand, ^bDepartment of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand, and ^cMaterials and Textile Technology, Faculty of Science and Technology, Thammasat University, Khlong Luang, Pathum Thani 12121, Thailand
^*Correspondence e-mail: ratanonc@nu.ac.th

Edited by M. Weil, Vienna University of Technology, Austria (Received 13 February 2018; accepted 22 March 2018; online 27 March 2018)

In the title hydrated azo compound, C₈H₈N₆S·H₂O, the two aromatic groups are close to coplanar with the dihedral angle between the mean planes of the thiazole and pyridine rings being 2.9 (2)°. The organic molecule adopts an E configuration with respect to the double bond of the azo bridge. In the crystal, molecules are linked by (amine)N—H⋯N(pyridine), (amine)N—H⋯O(water) and (water)O—H⋯N(thiazole) hydrogen bonds along with π–π interactions involving pairs of thiazole rings and pairs of pyridine rings. The plane-to-plane distance between two parallel molecules is 3.7856 (4) Å and corresponds to the length of the a axis. In this way, a layer structure parallel to (010) is formed. The layers are linked by weak C—H⋯S hydrogen bonds, eventually resulting in a three-dimensional network.

Keywords: crystal structure; azo dyes; hydrogen bonding; π–π stacking.

CCDC reference: 1831600

1. Chemical context

Azo compounds are one of the most important organic dyes used in industrial applications to colour various consumer goods such as leather, plastics and cosmetics (Kaur et al., 2018 ). The main characteristic of these compounds is the chromophore of the azo group (–N=N–), which is responsible for the color of the dyes. Compounds with an aromatic thiazolylazo moiety are a subclass of azo dyes, which contain the thiazole group on one side of the azo linkage and are important ligands in coordination chemistry (Kaim, 2001 ). In this regard, zinc complexes with polydentate chelating thiazolylazo ligands have been prepared as luminescence probes for selectively sensing phosphates (Hens et al., 2015 ). Recently, Piyasaengthong et al. (2015 ) reported the synthesis of a gold(III) complex of 3-(2′-thiazolylazo)-2,6-diaminopyridine and investigated its pepsin inhibition.

We report here the crystal structure of 3-(2′-thiazolylazo)-2,6-diaminopyridine monohydrate, C₈H₈N₆S·H₂O, (I), obtained through the diazotization of 2-aminothiazole followed by a coupling reaction with 2,6-diaminopyridine (Montelongo et al., 1982 ).

2. Structural commentary

The molecular entities of (I) with atom labelling are presented in Fig. 1. The organic molecule has an E configuration with respect to the azo bridge (–N2=N3–), and is essentially planar with an r.m.s deviation of the fitted non-hydrogen atoms being 0.033 Å. The amine N5 and N6 atoms are 0.044 (2) and −0.059 (3) Å, respectively, out of this plane. The thiazole ring (C1–C3, N1, S1) makes a dihedral angle of 2.9 (2)° with the pyridine ring (C4–C8, N4). An intramolecular N5—H5A⋯N2 hydrogen bond is observed (Table 1), showing an S(6) ring motif.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯S1ⁱ	0.93	3.02	3.665 (3)	128
N5—H5A⋯N2	0.86 (1)	2.03 (3)	2.645 (4)	128 (3)
N5—H5A⋯O1	0.86 (1)	2.59 (2)	3.314 (4)	143 (3)
N5—H5B⋯N4ⁱⁱ	0.86 (1)	2.14 (1)	2.998 (4)	172 (3)
N6—H6A⋯O1ⁱⁱ	0.86 (1)	2.27 (2)	3.048 (4)	151 (4)
N6—H6B⋯O1ⁱⁱⁱ	0.86 (1)	2.13 (1)	2.988 (4)	177 (4)
O1—H1A⋯N1	0.84 (1)	2.13 (3)	2.923 (4)	158 (6)
O1—H1B⋯N2^iv	0.84 (1)	2.31 (2)	3.143 (4)	170 (9)
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1; (iii) x-1, y, z+1; (iv) x+1, y, z.

Figure 1
The molecular structure of the organic entity and the water molecule in compound (I)

, with the atom labelling and displacement ellipsoids drawn at the 50% probability level.

3. Supramolecular features

In the crystal of (I), extensive (amine)N—H⋯N(pyridine), (amine)N—H⋯O(water) and (water)O—H⋯N(thiazole) hydrogen bonds (Table 1) are present. Together with π–π interactions involving pairs of thiazole rings and pairs of pyridine rings with a plane-to-plane distance between two parallel molecules of 3.7856 (4) Å, a layered structure parallel to the ac plane is formed (Fig. 2). Weak C—H⋯S hydrogen bonds between adjacent thiazole rings further consolidate the crystal packing, thus generating a three-dimensional network.

Figure 2
The unit-cell packing in (I)

, viewed approximately down [100]. The classical O—H⋯N, and N—H⋯O hydrogen bonds are shown as green dashed lines (see Table 1

for numerical details).

4. Database survey

A search of the Cambridge Structural Database (Groom et al., 2016 ) for compounds with the (E)-2-(pyridin-3-yldiazenyl)thiazole moiety gave no hits. However, structures of substituted thiazolylazo derivatives were found, for example, 5-(diethylamino)-2-(2-thiazolylazo)phenol (QAVNAD; Zhang et al., 2005 ), 4-(2′-thiazolylazo)pyrocatechol (TZAZPC; Apinitis, 1978 ), 1-(2-thiazolylazo)-6-bromo-2-naphthol (TAZBRN10; Kurahashi et al., 1976 ) and 1-(2-thiazolylazo)-2-naphthol (TAZNPL10; Kurahashi, 1976 ).

5. Synthesis and crystallization

2-Aminothiazole (1.0 g, 0.009 mol) was dissolved in 6 M hydrochloric acid (16 ml) with sodium nitrite (0.7 g, 0.01 mol). The mixture was stirred at a temperature between 268 and 273 K while a solution of 2,6-diaminopyridine (1.0 g, 0.009 mol) in 40 ml of 4 M hydrochloric acid was added. The reaction mixture was stirred for 1 h and then adjusted to pH 6.0 by 0.001 M sodium hydroxide. The red precipitate formed was filtered through suction and washed with water. Suitable crystals for X-ray analysis were grown by recrystallization using the vapor diffusion technique in a methanol-hexane mixture at 253 K [yield 1.12 g, 51%]. ¹H NMR (400 MHz, 298 K, C₂D₆OS): δ 6.10 (d, m-ArH py, 1H), 7.39 (d, thiazole-H, 1H), 7.55 (d, p-ArH py, 1H), 7.703 (d, thiazole-H, 1H). Mass spec. (ESI) m/z 220.9 (M⁺), 136.2, 108.3, 81.4. IR–KBr (cm⁻¹): 3335 (w), 3217 (w), 3082 (w), 1660 (s), 1631 (s), 1454 (m), 1292 (s), 1159 (m). Analysis calculated for C₈H₁₀N₆OS: C, 43.64; H, 3.66; N, 38.16; 14.56. Found: C, 43.80; H, 3.79; N, 38.45; S,14.78.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms bonded to O and N atoms were located in difference-Fourier maps and refined with distance restraints of 0.84±0.02 Å with U_iso(H) = 1.5U_eq(O) and 0.86±0.02 Å with U_iso(H) = 1.2U_eq(N), respectively. The C-bound H atoms were included in calculated positions and treated as riding atoms: C—H = 0.93 Å with U_iso(H) = 1.2U_eq(C).

Table 2
Experimental details

Crystal data
Chemical formula	C₈H₈N₆S·H₂O
M_r	238.28
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	3.7856 (4), 28.393 (3), 9.6324 (9)
β (°)	93.824 (3)
V (Å³)	1033.02 (17)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.30
Crystal size (mm)	0.28 × 0.08 × 0.04

Data collection
Diffractometer	Bruker D8 QUEST CMOS
Absorption correction	Multi-scan (SADABS; Bruker, 2016 )
T_min, T_max	0.644, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	11837, 2100, 1670
R_int	0.054
(sin θ/λ)_max (Å⁻¹)	0.630

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.061, 0.121, 1.17
No. of reflections	2100
No. of parameters	169
No. of restraints	6
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.26
Computer programs: APEX3 and SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 1831600

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989018004693/wm5438sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018004693/wm5438Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989018004693/wm5438Isup3.cdx

Supporting information file. DOI: https://doi.org/10.1107/S2056989018004693/wm5438Isup4.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

3-[2-(1,3-Thiazol-2-yl)diazen-1-yl]pyridine-2,6-diamine monohydrate top

Crystal data top

C₈H₈N₆S·H₂O	F(000) = 496
M_r = 238.28	D_x = 1.532 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 3.7856 (4) Å	Cell parameters from 4156 reflections
b = 28.393 (3) Å	θ = 3.0–26.6°
c = 9.6324 (9) Å	µ = 0.30 mm⁻¹
β = 93.824 (3)°	T = 296 K
V = 1033.02 (17) Å³	Needle, dark orange
Z = 4	0.28 × 0.08 × 0.04 mm

Data collection top

Bruker D8 QUEST CMOS diffractometer	2100 independent reflections
Radiation source: microfocus sealed x-ray tube, Incoatec Iµus	1670 reflections with I > 2σ(I)
GraphiteDouble Bounce Multilayer Mirror monochromator	R_int = 0.054
Detector resolution: 10.5 pixels mm^-1	θ_max = 26.6°, θ_min = 3.6°
ω and φ scans	h = −4→4
Absorption correction: multi-scan (SADABS; Bruker, 2016)	k = −35→35
T_min = 0.644, T_max = 0.745	l = −12→11
11837 measured reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.061	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.121	w = 1/[σ²(F_o²) + (0.0131P)² + 1.7616P] where P = (F_o² + 2F_c²)/3
S = 1.17	(Δ/σ)_max < 0.001
2100 reflections	Δρ_max = 0.33 e Å⁻³
169 parameters	Δρ_min = −0.26 e Å⁻³
6 restraints

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
S1	0.1445 (2)	0.72666 (3)	0.18385 (9)	0.0377 (2)
N1	0.4021 (8)	0.65791 (9)	0.0492 (3)	0.0356 (6)
N2	0.2953 (7)	0.63596 (9)	0.2749 (3)	0.0317 (6)
N3	0.1805 (7)	0.65155 (9)	0.3905 (3)	0.0310 (6)
N4	0.2611 (7)	0.54434 (8)	0.6116 (3)	0.0299 (6)
N5	0.4246 (8)	0.55257 (10)	0.3899 (3)	0.0379 (7)
N6	0.1041 (9)	0.53404 (10)	0.8343 (3)	0.0437 (8)
C1	0.2378 (10)	0.73517 (12)	0.0133 (4)	0.0415 (8)
H1	0.2022	0.7632	−0.0355	0.050*
C2	0.3691 (10)	0.69560 (12)	−0.0395 (4)	0.0409 (8)
H2	0.4337	0.6939	−0.1308	0.049*
C3	0.2931 (8)	0.66920 (10)	0.1706 (3)	0.0303 (7)
C4	0.1707 (8)	0.62052 (10)	0.4978 (3)	0.0284 (7)
C5	0.2873 (8)	0.57206 (10)	0.4993 (3)	0.0279 (7)
C6	0.1248 (8)	0.56226 (10)	0.7246 (3)	0.0306 (7)
C7	0.0081 (9)	0.60975 (11)	0.7330 (3)	0.0342 (7)
H7	−0.0845	0.6212	0.8134	0.041*
C8	0.0359 (8)	0.63760 (11)	0.6209 (3)	0.0335 (7)
H8	−0.0357	0.6689	0.6250	0.040*
O1	0.7912 (8)	0.56959 (9)	0.0910 (3)	0.0489 (7)
H5A	0.471 (9)	0.5698 (10)	0.320 (2)	0.040 (10)*
H5B	0.504 (9)	0.5242 (6)	0.397 (4)	0.047 (11)*
H6A	0.166 (10)	0.5050 (5)	0.826 (4)	0.058 (12)*
H6B	0.022 (10)	0.5438 (12)	0.910 (2)	0.052 (12)*
H1A	0.647 (12)	0.5905 (15)	0.062 (6)	0.11 (2)*
H1B	0.936 (19)	0.584 (3)	0.145 (8)	0.23 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0472 (5)	0.0283 (4)	0.0375 (5)	0.0039 (4)	0.0011 (4)	−0.0003 (3)
N1	0.0457 (16)	0.0316 (14)	0.0299 (15)	−0.0034 (12)	0.0044 (13)	−0.0004 (11)
N2	0.0362 (15)	0.0295 (13)	0.0295 (15)	0.0017 (11)	0.0028 (12)	0.0031 (11)
N3	0.0332 (14)	0.0286 (13)	0.0313 (15)	0.0013 (11)	0.0018 (12)	0.0008 (11)
N4	0.0342 (14)	0.0265 (13)	0.0292 (14)	0.0033 (11)	0.0048 (12)	0.0011 (10)
N5	0.0555 (19)	0.0264 (14)	0.0331 (16)	0.0100 (13)	0.0127 (14)	0.0034 (12)
N6	0.064 (2)	0.0359 (16)	0.0331 (17)	0.0112 (15)	0.0151 (15)	0.0028 (13)
C1	0.053 (2)	0.0324 (17)	0.037 (2)	−0.0067 (15)	−0.0083 (17)	0.0076 (14)
C2	0.054 (2)	0.0386 (18)	0.0298 (18)	−0.0102 (16)	0.0034 (16)	0.0041 (14)
C3	0.0321 (17)	0.0261 (15)	0.0323 (18)	−0.0027 (12)	0.0002 (14)	−0.0006 (12)
C4	0.0305 (16)	0.0259 (14)	0.0287 (16)	0.0015 (12)	0.0006 (13)	0.0007 (12)
C5	0.0273 (15)	0.0266 (15)	0.0300 (17)	0.0002 (12)	0.0028 (13)	−0.0027 (12)
C6	0.0309 (16)	0.0309 (16)	0.0301 (17)	0.0002 (13)	0.0033 (14)	0.0002 (12)
C7	0.0392 (18)	0.0327 (16)	0.0314 (18)	0.0054 (14)	0.0082 (15)	−0.0043 (13)
C8	0.0376 (18)	0.0272 (15)	0.0355 (19)	0.0065 (13)	0.0021 (15)	−0.0019 (13)
O1	0.0621 (18)	0.0385 (14)	0.0474 (16)	0.0045 (13)	0.0123 (14)	−0.0006 (12)

Geometric parameters (Å, º) top

S1—C1	1.720 (4)	N6—H6A	0.863 (10)
S1—C3	1.733 (3)	N6—H6B	0.860 (10)
N1—C2	1.370 (4)	C1—H1	0.9300
N1—C3	1.305 (4)	C1—C2	1.342 (5)
N2—N3	1.300 (3)	C2—H2	0.9300
N2—C3	1.379 (4)	C4—C5	1.445 (4)
N3—C4	1.360 (4)	C4—C8	1.408 (4)
N4—C5	1.347 (4)	C6—C7	1.423 (4)
N4—C6	1.336 (4)	C7—H7	0.9300
N5—C5	1.326 (4)	C7—C8	1.348 (4)
N5—H5A	0.858 (10)	C8—H8	0.9300
N5—H5B	0.861 (10)	O1—H1A	0.841 (10)
N6—C6	1.333 (4)	O1—H1B	0.840 (10)

C1—S1—C3	88.47 (16)	N1—C3—N2	119.9 (3)
C3—N1—C2	110.2 (3)	N2—C3—S1	125.2 (2)
N3—N2—C3	113.9 (2)	N3—C4—C5	126.9 (3)
N2—N3—C4	117.2 (2)	N3—C4—C8	116.5 (3)
C6—N4—C5	119.0 (2)	C8—C4—C5	116.5 (3)
C5—N5—H5A	120 (2)	N4—C5—C4	121.7 (3)
C5—N5—H5B	119 (2)	N5—C5—N4	116.6 (3)
H5A—N5—H5B	121 (3)	N5—C5—C4	121.7 (3)
C6—N6—H6A	118 (3)	N4—C6—C7	123.0 (3)
C6—N6—H6B	122 (3)	N6—C6—N4	117.6 (3)
H6A—N6—H6B	120 (4)	N6—C6—C7	119.3 (3)
S1—C1—H1	124.8	C6—C7—H7	121.0
C2—C1—S1	110.4 (3)	C8—C7—C6	118.0 (3)
C2—C1—H1	124.8	C8—C7—H7	121.0
N1—C2—H2	122.0	C4—C8—H8	119.2
C1—C2—N1	116.0 (3)	C7—C8—C4	121.6 (3)
C1—C2—H2	122.0	C7—C8—H8	119.2
N1—C3—S1	114.9 (2)	H1A—O1—H1B	104 (7)

S1—C1—C2—N1	−0.1 (4)	C2—N1—C3—N2	178.4 (3)
N2—N3—C4—C5	2.5 (5)	C3—S1—C1—C2	0.0 (3)
N2—N3—C4—C8	−178.2 (3)	C3—N1—C2—C1	0.2 (5)
N3—N2—C3—S1	−1.5 (4)	C3—N2—N3—C4	179.2 (3)
N3—N2—C3—N1	−180.0 (3)	C5—N4—C6—N6	−179.6 (3)
N3—C4—C5—N4	−179.3 (3)	C5—N4—C6—C7	−0.7 (5)
N3—C4—C5—N5	0.5 (5)	C5—C4—C8—C7	−1.8 (5)
N3—C4—C8—C7	178.8 (3)	C6—N4—C5—N5	179.9 (3)
N4—C6—C7—C8	0.3 (5)	C6—N4—C5—C4	−0.3 (4)
N6—C6—C7—C8	179.3 (3)	C6—C7—C8—C4	1.0 (5)
C1—S1—C3—N1	0.1 (3)	C8—C4—C5—N4	1.4 (4)
C1—S1—C3—N2	−178.5 (3)	C8—C4—C5—N5	−178.8 (3)
C2—N1—C3—S1	−0.2 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···S1ⁱ	0.93	3.02	3.665 (3)	128
N5—H5A···N2	0.86 (1)	2.03 (3)	2.645 (4)	128 (3)
N5—H5A···O1	0.86 (1)	2.59 (2)	3.314 (4)	143 (3)
N5—H5B···N4ⁱⁱ	0.86 (1)	2.14 (1)	2.998 (4)	172 (3)
N6—H6A···O1ⁱⁱ	0.86 (1)	2.27 (2)	3.048 (4)	151 (4)
N6—H6B···O1ⁱⁱⁱ	0.86 (1)	2.13 (1)	2.988 (4)	177 (4)
O1—H1A···N1	0.84 (1)	2.13 (3)	2.923 (4)	158 (6)
O1—H1B···N2^iv	0.84 (1)	2.31 (2)	3.143 (4)	170 (9)

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

Funding information

RC and BB thank the Faculty of Science, Naresuan University for financial support. AS thanks the Development and Promotion of Science and Technology Talents Project (DPST) for a scholarship. The authors thank the Faculty of Science and Technology, Thammasat University, for funds to purchase the X-ray diffractometer.

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