Ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxyl­ate and 6-methylimidazo­[2,1-b]­thia­zole–2-amino-1,3-thia­zole (1/1)

Lynch, D.E.; McClenaghan, I.

doi:10.1107/S0108270104015471

organic compounds

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 60| Part 8| August 2004| Pages o592-o594

doi:10.1107/S0108270104015471

Ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate and 6-methylimidazo[2,1-b]thiazole–2-amino-1,3-thiazole (1/1)

Daniel E. Lynch ^a ^* and Ian McClenaghan ^b

^aSchool of Science and the Environment, Coventry University, Coventry CV1 5FB, England, and ^bKey Organics Ltd, Highfield Industrial Estate, Camelford, Cornwall PL32 9QZ, England
^*Correspondence e-mail: apx106@coventry.ac.uk

(Received 17 June 2004; accepted 24 June 2004; online 21 July 2004)

The structure of ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate, C₁₀H₁₆N₂O₂S, (I), and the structure of the 1:1 adduct 6-methylimidazo[2,1-b]thiazole–2-amino-1,3-thiazole (1/1), C₆H₆N₂S·C₃H₄N₂S, (II), have been determined. The molecules in (I) associate via a hydrogen-bonded R $[{_2^2}]$ (8) dimer consisting of N—H⋯N interactions, with the hydrogen-bonding array additionally involving N—H⋯O interactions to one of the carboxylate O atoms. The 2-aminothiazole molecules in (II) also associate via an N—H⋯N hydrogen-bonded R $[{_2^2}]$ (8) dimer, with an additional N—H⋯N interaction to the Nsp² atom of the imidazothiazole moiety, creating hydrogen-bonded quartets.

Comment

Aminothiazoles have been extensively studied for a range of biological and industrial applications (Lynch et al., 1999 ; Toplak et al., 2003 ). 2-Amino-1,3-thiazole, the structure of which was reported in 1982 (Caranoni & Reboul, 1982 ), is itself listed as a thyroid inhibitor (Merck, 2001 ). A search of the Cambridge Structural Database (CSD, Version 5.25 of April 2004; Allen, 2002 ) reveals that there are 73 crystal structures containing the 2-aminothiazole moiety, with 51 of those being pure organics. The present authors have recently published a paper on the packing modes of 2-amino-4-phenyl-1,3-thiazole derivatives (Lynch et al., 2002 ) and have been investigating the structural aspects of 2-aminothiazole derivatives for the last six years. One such compound reported during this time was ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate (Lynch & McClenaghan, 2002 ), which is currently the only structure of a 4-tert-butyl-5-ester derivative of an aminothiazole. However, we have recently determined the structure of ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate, (I), and report it here.

Another aminothiazole derivative is imidazo[2,1-b]thiazole, which has 11 analogues whose structures have previously been reported in the CSD. This bicyclic ring system can be prepared by refluxing a halomethyl ketone with 2-aminothiazole in ethanol. In an attempt to do so, using chloroacetone, an incomplete reaction yielded a mixture of the imidazo[2,1-b]thiazole derivative with the starting thiazole. The crystals that formed from the impure product were subsequently found to contain the 1:1 adduct of 6-methylimidazo[2,1-b]thiazole with 2-aminothiazole, (II), the structure of which is also reported here.

The structure of (I) consists of a single molecule (Fig. 1) which associates, via hydrogen-bonding interactions, to three symmetry-equivalent molecules (Fig. 2). One symmetry-equivalent molecule forms a hydrogen-bonded R $[{_2^2}]$ (8) graph-set dimer (Etter, 1990 ) with (I) through an N—H⋯N interaction (Table 1), a feature common for 2-aminothiazole derivatives, while the other two associate to and from (I) through an N—H⋯O interaction. A similar packing mode has previously been observed in the structure of ethyl 2-amino-4-phenyl-1,3-thiazole-5-carboxylate (Lynch et al., 2002), but is not observed in any other 5-ester-substituted 2-aminothiazole. This is probably due to the fact that, in each of these other structures, there are alternative exocyclic hydrogen-bonding acceptor atoms in addition to the two carboxylate O atoms. The ethyl chain twists out of the plane of the thiazole ring, with the C51—O52—C53—C54 torsion angle being 85.5 (2)°, compared with −168.5 (3)° in ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate (Lynch & McClenaghan, 2002). One of the methyl groups in the tert-butyl moiety is aligned with the thiazole ring, with the N3—C4—C41—C42 torsion angle being −1.8 (2)°, similar to what was observed in ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate [comparative torsion angle = 7.2 (5)°].

The structure of (II) comprises two adduct molecules associated by a single hydrogen-bonding interaction from one of the 2-amino H atoms to the Nsp² atom in the imidazothiazole system (Fig. 3). Although one of the present authors (DEL) has determined 16 co-crystal structures containing 2-aminothiazole derivatives, there are only two previously reported co-crystals containing 2-aminothiazole itself (Kuz'mina & Struchkov, 1984 ; Moers et al., 2000 ), and both of these are organic salts. The structure of (II) is unique in that it is the first adduct (not an organic salt) of 2-aminothiazole. The molecules in (II) pack across an inversion centre to construct an associated quartet, with the 2-aminothiazoles forming a hydrogen-bonded R $[{_2^2}]$ (8) graph-set dimer (Fig. 4). Hydrogen-bonding associations are listed in Table 2. A C—H⋯N close contact is also observed between atom C2A and the 2-amino N atom. The distance between atoms N7A and S1B is 3.294 (3) Å.

The determination of the structure of (II) and examination of the packing associations may now lead to a series of adducts containing 2-aminothiazole and heterocyclic bases, as opposed to continuing to try to obtain co-crystals (either adducts or organic salts) with organic acids.

Figure 1
The molecular configuration and atom-numbering scheme for (I

). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.

Figure 2
A packing diagram for (I

). [Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) $[{3 \over 2}]$ − x, y + $[{1 \over 2}]$ , $[{3 \over 2}]$ − z.]

Figure 3
The molecular configuration and atom-numbering scheme for (II

). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.

Figure 4
A packing diagram for (II

). [Symmetry code: (i) −x, 1 − y, 1 − z.]

Experimental

Compound (I) was obtained from Key Organics Ltd and was crystallized from ethanol. Compound (II) was prepared by refluxing equimolar amounts of 2-amino-1,3-thiazole and chloroacetone in ethanol for 16 h. Upon removal of the reaction solvent, the product was washed with aqueous NaOH and then extracted into dichloromethane. Crystals of (II) grew from the resultant liquid after removal of the extraction solvent.

Compound (I)

Crystal data

C₁₀H₁₆N₂O₂S
M_r = 228.31
Monoclinic, P2₁/n
a = 10.6248 (8) Å
b = 8.6055 (5) Å
c = 13.0135 (9) Å
β = 92.977 (4)°
V = 1188.24 (14) Å³
Z = 4
D_x = 1.276 Mg m⁻³
Mo Kα radiation
Cell parameters from 3289 reflections
θ = 2.9–27.5°
μ = 0.26 mm⁻¹
T = 120 (2) K
Prism, colourless
0.42 × 0.32 × 0.08 mm

Data collection

Bruker–Nonius KappaCCD area-detector diffractometer
φ and ω scans
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ) T_min = 0.913, T_max = 0.977
9227 measured reflections
2093 independent reflections
1668 reflections with I > 2σ(I)
R_int = 0.082
θ_max = 25.0°
h = −12 → 12
k = −10 → 10
l = −15 → 15

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.041
wR(F²) = 0.106
S = 1.08
2093 reflections
140 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0601P)² + 0.0328P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.34 e Å⁻³

Table 1
Hydrogen-bonding geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N21—H21⋯N3ⁱ	0.88	2.14	3.016 (2)	173
N21—H22⋯O51ⁱⁱ	0.88	2.02	2.858 (2)	158
Symmetry codes: (i) 1-x,1-y,1-z; (ii) $[{\script{3\over 2}}-x,{\script{1\over 2}}+y,{\script{3\over 2}}-z]$ .

Compound (II)

Crystal data

C₆H₆N₂S·C₃H₄N₂S
M_r = 238.33
Triclinic, $[P\overline 1]$
a = 6.9195 (2) Å
b = 9.1860 (2) Å
c = 9.6953 (3) Å
α = 69.5204 (17)°
β = 71.4823 (16)°
γ = 74.2770 (17)°
V = 538.48 (3) Å³
Z = 2
D_x = 1.470 Mg m⁻³
Mo Kα radiation
Cell parameters from 9410 reflections
θ = 2.9–27.5°
μ = 0.47 mm⁻¹
T = 120 (2) K
Plate, colourless
0.26 × 0.08 × 0.04 mm

Data collection

Bruker–Nonius KappaCCD area-detector diffractometer
φ and ω scans
Absorption correction: multi-scan (SORTAV; Blessing, 1995) T_min = 0.885, T_max = 0.982
12 593 measured reflections
2472 independent reflections
2224 reflections with I > 2σ(I)
R_int = 0.072
θ_max = 27.6°
h = −8 → 9
k = −11 → 11
l = −12 → 12

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.040
wR(F²) = 0.105
S = 1.05
2472 reflections
137 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0468P)² + 0.3904P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.44 e Å⁻³

Table 2
Hydrogen-bonding geometry (Å, °) for (II)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N21B—H21B⋯N3Bⁱ	0.88	2.14	3.010 (2)	170
N21B—H22B⋯N7A	0.88	2.10	2.933 (2)	159
C2A—H2A⋯N21Bⁱⁱ	0.95	2.59	3.531 (2)	174
Symmetry codes: (i) -x,1-y,1-z; (ii) x,y-1,z.

All H atoms were included in the refinement at calculated positions in the riding-model approximation, with N—H distances of 0.88 Å, and C—H distances of 0.95 (aromatic H atoms), 0.98 (CH₃ H atoms) and 0.99 Å (CH₂ H atoms), and with U_iso(H) = 1.25U_eq(C,N).

For both compounds, data collection: DENZO (Otwinowski & Minor, 1997 ) and COLLECT (Nonius, 1998 ); cell refinement: DENZO and COLLECT; data reduction: DENZO, SCALEPACK (Otwinowski & Minor, 1997) and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLUTON94 (Spek, 1994 ) and PLATON97 (Spek, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, II, global. DOI: 10.1107/S0108270104015471/sk1738sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270104015471/sk1738Isup2.hkl

Structure factors: contains datablock II. DOI: 10.1107/S0108270104015471/sk1738IIsup3.hkl

Comment top

Aminothiazoles have been extensively studied for a range of biological and industrial applications (Lynch et al., 1999; Toplak et al., 2003). 2-Amino-1,3-thiazole, the structure of which was reported in 1982 (Caranoni & Reboul, 1982), is itself listed as a thyroid inhibitor (Merck Index, 2001). A search of the Cambridge Structural Database (CSD, Version?; Allen, 2002) reveals that there are 73 crystal structures containing the 2-aminothiazole moiety, with 51 of those being pure organics. The present authors have recently published a paper on the packing modes of 2-amino-4-phenyl-1,3-thiazole derivatives (Lynch et al., 2002) and have been investigating the structural aspects of 2-aminothiazole derivatives for the last six years. One such compound reported during this time was ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate (Lynch & McClenaghan, 2002), which is currently the only structure of a 4-tert-butyl-5-ester derivative of an aminothiazole. However, we have recently determined the structure of ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate, (I), and report it here.

Another aminothiazole derivative is imidazo[2,1-b]thiazole, which has 11 analogues whose structures have been previously reported in the CSD. This bicyclic ring system can be prepared by refluxing a halomethylketone with 2-aminothiazole in ethanol. In an attempt to do so, using chloroacetone, an incomplete reaction yielded a mixture of the imidazo[2,1-b]thiazole derivative with the starting thiazole. The crystals that formed from the impure product were subsequently found to contain the 1:1 adduct of 6-methylimidazo[2,1-b]thiazole with 2-aminothiazole, (II), the structure of which is also reported here. \sch

The structure of (I) consists of a single molecule (Fig. 1) which associates, via hydrogen-bonding interactions, to three symmetry-equivalent molecules (Fig. 2). One symmetry-equivalent molecule forms a hydrogen-bonded R₂²(8) graph-set dimer (Etter, 1990) with (I) through an N—H···N interaction (Table 1), a feature common for 2-aminothiazole derivatives, while the other two associate to and from (I) through an N—H···O interaction. A similar packing mode has previously been observed in the structure of ethyl 2-amino-4-phenyl-1,3-thiazole-5-carboxylate (Lynch et al., 2002), but is not observed in any other 5-ester substituted 2-aminothiazole. This is probably due to the fact that, in each of these other structures, there are alternative exocyclic hydrogen-bonding acceptor atoms in addition to the two carboxylate O atoms. The ethyl chain twists out of the plane of the thiazole ring, with the C51—O52—C53—C54 torsion angle being 85.5 (2)°, compared with −168.5 (3)° in ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate (Lynch & McClenaghan, 2002). One of the methyl groups in the tert-butyl moiety is aligned with the thiazole ring, with the N3—C4—C41—C42 torsion angle being −1.8 (2)°, similar to what was observed in ethyl 4-tert-butyl-2-(3-phenylureido)-1,3-thiazole-5-carboxylate [comparative torsion angle 7.2 (5)°].

The structure of (II) comprises two adduct molecules associated by a single hydrogen-bonding interaction from one of the 2-amino H atoms to the Nsp² atom in the imidazothiazole (Fig. 3). Although one of the present authors (DEL) has determined 16 co-crystal structures containing 2-aminothiazole derivatives, there are only two previously reported co-crystals containing 2-aminothiazole itself (Kuz'mina & Struchkov, 1984; Moers et al., 2000), and both of these are organic salts. The structure of (II) is unique in that it is the first adduct (not an organic salt) of 2-aminothiazole. The molecules in (II) pack across an inversion centre to construct an associated quartet, with the 2-aminothiazoles forming a hydrogen-bonded R₂²(8) graph-set dimer (Fig. 4). Hydrogen-bonding associations are listed in Table 2. A C—H···N close contact is also observed between atom C2A and the 2-amino N atom. The distance between atoms N7A and S1B is 3.294 (3) Å.

The determination of the structure of (II), and examination of the packing associations, may now lead to a series of adducts containing 2-aminothiazole and heterocyclic bases, as opposed to continuing to try to obtain co-crystals (either adducts or organic salts) with organic acids.

Experimental top

Compound (I) was obtained from Key Organics Ltd. and was crystallized from ethanol. Compound (II) was prepared by refluxing equimolar amounts of 2-amino-1,3-thiazole and chloroacetone in ethanol for 16 h. Upon removal of the reaction solvent, the product was washed with aqueous NaOH and then extracted into dichloromethane. Crystals of (II) grew from the resultant liquid after removal of the extraction solvent.

Computing details top

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1998) for (I); DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998) for (II). For both compounds, cell refinement: DENZO and COLLECT; data reduction: DENZO, SCALEPACK (Otwinowski & Minor, 1997) and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLUTON94 (Spek, 1994) and PLATON97 (Spek, 1997); software used to prepare material for publication: SHELXL97.

Figures top

	Fig. 1. The molecular configuration and atom-numbering scheme for (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A packing diagram for (I). [Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) 3/2 − x, y + 1/2, 3/2 − z.]
	Fig. 3. The molecular configuration and atom-numbering scheme for (II). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 4. A packing diagram for (II). [Symmetry code: (i) −x, 1 − y, 1 − z.]

(I) Ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate top

Crystal data top

C₁₀H₁₆N₂O₂S	F(000) = 488
M_r = 228.31	D_x = 1.276 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3289 reflections
a = 10.6248 (8) Å	θ = 2.9–27.5°
b = 8.6055 (5) Å	µ = 0.26 mm⁻¹
c = 13.0135 (9) Å	T = 120 K
β = 92.977 (4)°	Prism, colourless
V = 1188.24 (14) Å³	0.42 × 0.32 × 0.08 mm
Z = 4

Data collection top

Bruker-Nonius KappaCCD area-detector diffractometer	2093 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	1668 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.082
Detector resolution: 9.091 pixels mm^-1	θ_max = 25.0°, θ_min = 3.1°
ϕ and ω scans	h = −12→12
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −10→10
T_min = 0.913, T_max = 0.977	l = −15→15
9227 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.106	H-atom parameters constrained
S = 1.08	w = 1/[σ²(F_o²) + (0.0601P)² + 0.0328P] where P = (F_o² + 2F_c²)/3
2093 reflections	(Δ/σ)_max < 0.001
140 parameters	Δρ_max = 0.20 e Å⁻³
0 restraints	Δρ_min = −0.34 e Å⁻³

Crystal data top

C₁₀H₁₆N₂O₂S	V = 1188.24 (14) Å³
M_r = 228.31	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 10.6248 (8) Å	µ = 0.26 mm⁻¹
b = 8.6055 (5) Å	T = 120 K
c = 13.0135 (9) Å	0.42 × 0.32 × 0.08 mm
β = 92.977 (4)°

Data collection top

Bruker-Nonius KappaCCD area-detector diffractometer	2093 independent reflections
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	1668 reflections with I > 2σ(I)
T_min = 0.913, T_max = 0.977	R_int = 0.082
9227 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.041	0 restraints
wR(F²) = 0.106	H-atom parameters constrained
S = 1.08	Δρ_max = 0.20 e Å⁻³
2093 reflections	Δρ_min = −0.34 e Å⁻³
140 parameters

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

	x	y	z	U_iso*/U_eq
S1	0.73102 (5)	0.23587 (6)	0.65724 (3)	0.02690 (19)
C2	0.62597 (18)	0.3504 (2)	0.58627 (14)	0.0256 (5)
N21	0.57163 (16)	0.47329 (19)	0.62767 (12)	0.0318 (4)
H21	0.5186	0.5309	0.5900	0.040*
H22	0.5887	0.4969	0.6927	0.040*
N3	0.60506 (15)	0.30740 (18)	0.48900 (11)	0.0242 (4)
C4	0.67079 (18)	0.1747 (2)	0.46746 (14)	0.0233 (4)
C41	0.64797 (18)	0.1044 (2)	0.35997 (14)	0.0260 (5)
C42	0.5490 (2)	0.1988 (3)	0.29758 (15)	0.0366 (5)
H41	0.4713	0.2036	0.3348	0.046*
H42	0.5316	0.1491	0.2306	0.046*
H43	0.5807	0.3043	0.2873	0.046*
C43	0.7696 (2)	0.1048 (2)	0.30173 (15)	0.0326 (5)
H44	0.8007	0.2116	0.2964	0.041*
H45	0.7526	0.0622	0.2326	0.041*
H46	0.8333	0.0411	0.3389	0.041*
C44	0.5958 (2)	−0.0610 (2)	0.37003 (15)	0.0306 (5)
H47	0.6590	−0.1266	0.4064	0.038*
H48	0.5759	−0.1039	0.3013	0.038*
H49	0.5191	−0.0581	0.4088	0.038*
C5	0.74610 (18)	0.1188 (2)	0.54923 (14)	0.0249 (4)
C51	0.83058 (18)	−0.0117 (2)	0.56901 (14)	0.0261 (5)
O51	0.87845 (14)	−0.03732 (17)	0.65452 (10)	0.0345 (4)
O52	0.85479 (13)	−0.09931 (15)	0.48804 (9)	0.0288 (3)
C53	0.9321 (2)	−0.2367 (2)	0.50785 (16)	0.0312 (5)
H51	0.9964	−0.2144	0.5637	0.039*
H52	0.9764	−0.2640	0.4452	0.039*
C54	0.8522 (3)	−0.3706 (2)	0.5382 (2)	0.0484 (6)
H53	0.8094	−0.3440	0.6008	0.060*
H54	0.9055	−0.4621	0.5512	0.060*
H55	0.7893	−0.3933	0.4825	0.060*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0291 (3)	0.0302 (3)	0.0211 (3)	0.0021 (2)	−0.0018 (2)	−0.0009 (2)
C2	0.0268 (11)	0.0267 (10)	0.0232 (10)	−0.0036 (8)	−0.0002 (8)	0.0000 (8)
N21	0.0404 (11)	0.0325 (9)	0.0220 (8)	0.0094 (8)	−0.0049 (7)	−0.0022 (8)
N3	0.0277 (9)	0.0246 (8)	0.0203 (8)	−0.0001 (7)	−0.0004 (7)	−0.0006 (7)
C4	0.0235 (10)	0.0247 (10)	0.0219 (9)	−0.0045 (8)	0.0031 (8)	0.0015 (8)
C41	0.0264 (11)	0.0305 (11)	0.0213 (9)	0.0015 (8)	0.0012 (8)	0.0005 (8)
C42	0.0438 (14)	0.0413 (12)	0.0237 (10)	0.0090 (10)	−0.0068 (9)	−0.0071 (9)
C43	0.0385 (13)	0.0374 (12)	0.0225 (10)	0.0001 (10)	0.0071 (9)	0.0011 (9)
C44	0.0306 (12)	0.0337 (11)	0.0276 (10)	−0.0024 (9)	0.0029 (9)	−0.0067 (9)
C5	0.0272 (11)	0.0270 (10)	0.0208 (9)	−0.0024 (8)	0.0030 (8)	0.0006 (8)
C51	0.0255 (11)	0.0292 (11)	0.0239 (10)	−0.0035 (8)	0.0039 (8)	0.0021 (9)
O51	0.0395 (9)	0.0393 (9)	0.0241 (7)	0.0101 (7)	−0.0042 (6)	0.0016 (6)
O52	0.0315 (8)	0.0315 (8)	0.0233 (7)	0.0067 (6)	0.0017 (6)	−0.0011 (6)
C53	0.0293 (12)	0.0332 (11)	0.0315 (11)	0.0087 (9)	0.0046 (9)	0.0010 (9)
C54	0.0551 (16)	0.0331 (12)	0.0583 (15)	0.0020 (11)	0.0163 (13)	0.0017 (12)

Geometric parameters (Å, º) top

S1—C2	1.7214 (19)	C43—H45	0.98
S1—C5	1.7434 (18)	C43—H46	0.98
C2—N3	1.327 (2)	C44—H47	0.98
C2—N21	1.332 (2)	C44—H48	0.98
N21—H21	0.88	C44—H49	0.98
N21—H22	0.88	C5—C51	1.452 (3)
N3—C4	1.375 (2)	C51—O51	1.219 (2)
C4—C5	1.384 (3)	C51—O52	1.332 (2)
C4—C41	1.532 (2)	O52—C53	1.455 (2)
C41—C42	1.529 (3)	C53—C54	1.496 (3)
C41—C43	1.532 (3)	C53—H51	0.99
C41—C44	1.535 (3)	C53—H52	0.99
C42—H41	0.98	C54—H53	0.98
C42—H42	0.98	C54—H54	0.98
C42—H43	0.98	C54—H55	0.98
C43—H44	0.98

C2—S1—C5	88.99 (9)	H44—C43—H46	109.5
N3—C2—N21	123.57 (17)	H45—C43—H46	109.5
N3—C2—S1	115.09 (14)	C41—C44—H47	109.5
N21—C2—S1	121.34 (14)	C41—C44—H48	109.5
C2—N21—H21	120.0	H47—C44—H48	109.5
C2—N21—H22	120.0	C41—C44—H49	109.5
H21—N21—H22	120.0	H47—C44—H49	109.5
C2—N3—C4	111.38 (15)	H48—C44—H49	109.5
N3—C4—C5	114.28 (16)	C4—C5—C51	137.07 (18)
N3—C4—C41	117.14 (15)	C4—C5—S1	110.22 (14)
C5—C4—C41	128.52 (17)	C51—C5—S1	112.69 (13)
C42—C41—C4	110.29 (16)	O51—C51—O52	122.07 (17)
C42—C41—C43	108.08 (16)	O51—C51—C5	121.76 (18)
C4—C41—C43	110.68 (16)	O52—C51—C5	116.15 (16)
C42—C41—C44	107.26 (17)	C51—O52—C53	116.77 (14)
C4—C41—C44	109.21 (15)	O52—C53—C54	110.44 (17)
C43—C41—C44	111.25 (16)	O52—C53—H51	109.6
C41—C42—H41	109.5	C54—C53—H51	109.6
C41—C42—H42	109.5	O52—C53—H52	109.6
H41—C42—H42	109.5	C54—C53—H52	109.6
C41—C42—H43	109.5	H51—C53—H52	108.1
H41—C42—H43	109.5	C53—C54—H53	109.5
H42—C42—H43	109.5	C53—C54—H54	109.5
C41—C43—H44	109.5	H53—C54—H54	109.5
C41—C43—H45	109.5	C53—C54—H55	109.5
H44—C43—H45	109.5	H53—C54—H55	109.5
C41—C43—H46	109.5	H54—C54—H55	109.5

C5—S1—C2—N3	−1.16 (16)	C41—C4—C5—C51	2.1 (4)
C5—S1—C2—N21	179.29 (17)	N3—C4—C5—S1	1.1 (2)
N21—C2—N3—C4	−178.48 (18)	C41—C4—C5—S1	−176.03 (16)
S1—C2—N3—C4	2.0 (2)	C2—S1—C5—C4	0.00 (15)
C2—N3—C4—C5	−2.0 (2)	C2—S1—C5—C51	−178.60 (15)
C2—N3—C4—C41	175.51 (16)	C4—C5—C51—O51	−174.3 (2)
N3—C4—C41—C42	−1.8 (2)	S1—C5—C51—O51	3.8 (2)
C5—C4—C41—C42	175.29 (19)	C4—C5—C51—O52	7.1 (3)
N3—C4—C41—C43	117.77 (19)	S1—C5—C51—O52	−174.81 (13)
C5—C4—C41—C43	−65.2 (3)	O51—C51—O52—C53	5.6 (3)
N3—C4—C41—C44	−119.42 (18)	C5—C51—O52—C53	−175.82 (16)
C5—C4—C41—C44	57.7 (3)	C51—O52—C53—C54	85.5 (2)
N3—C4—C5—C51	179.2 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N21—H21···N3ⁱ	0.88	2.14	3.016 (2)	173
N21—H22···O51ⁱⁱ	0.88	2.02	2.858 (2)	158

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

(II) 6-Methylimidazo[2,1-b]thiazole 2-amino-1,3-thiazole top

Crystal data top

C₆H₆N₂S·C₃H₄N₂S	Z = 2
M_r = 238.33	F(000) = 248
Triclinic, P1	D_x = 1.470 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.9195 (2) Å	Cell parameters from 9410 reflections
b = 9.1860 (2) Å	θ = 2.9–27.5°
c = 9.6953 (3) Å	µ = 0.47 mm⁻¹
α = 69.5204 (17)°	T = 120 K
β = 71.4823 (16)°	Plate, colourless
γ = 74.2770 (17)°	0.26 × 0.08 × 0.04 mm
V = 538.48 (3) Å³

Data collection top

Bruker-Nonius KappaCCD area-detector diffractometer	2472 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	2224 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.072
Detector resolution: 9.091 pixels mm^-1	θ_max = 27.6°, θ_min = 3.2°
ϕ and ω scans	h = −8→9
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −11→11
T_min = 0.885, T_max = 0.982	l = −12→12
12593 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.105	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0468P)² + 0.3904P] where P = (F_o² + 2F_c²)/3
2472 reflections	(Δ/σ)_max < 0.001
137 parameters	Δρ_max = 0.26 e Å⁻³
0 restraints	Δρ_min = −0.44 e Å⁻³

Crystal data top

C₆H₆N₂S·C₃H₄N₂S	γ = 74.2770 (17)°
M_r = 238.33	V = 538.48 (3) Å³
Triclinic, P1	Z = 2
a = 6.9195 (2) Å	Mo Kα radiation
b = 9.1860 (2) Å	µ = 0.47 mm⁻¹
c = 9.6953 (3) Å	T = 120 K
α = 69.5204 (17)°	0.26 × 0.08 × 0.04 mm
β = 71.4823 (16)°

Data collection top

Bruker-Nonius KappaCCD area-detector diffractometer	2472 independent reflections
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	2224 reflections with I > 2σ(I)
T_min = 0.885, T_max = 0.982	R_int = 0.072
12593 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.040	0 restraints
wR(F²) = 0.105	H-atom parameters constrained
S = 1.05	Δρ_max = 0.26 e Å⁻³
2472 reflections	Δρ_min = −0.44 e Å⁻³
137 parameters

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

	x	y	z	U_iso*/U_eq
S1A	0.00960 (8)	−0.08327 (6)	0.30204 (5)	0.03224 (15)
C2A	0.1187 (3)	−0.2132 (2)	0.1913 (2)	0.0286 (4)
H2A	0.1030	−0.3207	0.2263	0.036*
C3A	0.2265 (3)	−0.1461 (2)	0.0524 (2)	0.0243 (4)
H3A	0.2955	−0.1999	−0.0225	0.030*
N4A	0.2258 (2)	0.01230 (17)	0.03015 (16)	0.0202 (3)
C5A	0.3102 (3)	0.1371 (2)	−0.0801 (2)	0.0233 (4)
H5A	0.3949	0.1379	−0.1790	0.029*
C6A	0.2462 (3)	0.2595 (2)	−0.0171 (2)	0.0226 (4)
C61A	0.2951 (3)	0.4226 (2)	−0.0846 (2)	0.0301 (4)
H61A	0.3603	0.4435	−0.0190	0.038*
H62A	0.1670	0.4996	−0.0937	0.038*
H63A	0.3902	0.4316	−0.1855	0.038*
N7A	0.1235 (2)	0.21473 (18)	0.12958 (17)	0.0249 (3)
C8A	0.1169 (3)	0.0656 (2)	0.15266 (19)	0.0226 (4)
S1B	0.43793 (7)	0.20121 (5)	0.32915 (5)	0.02753 (15)
C2B	0.2352 (3)	0.3412 (2)	0.39595 (19)	0.0214 (3)
N21B	0.0592 (2)	0.38726 (19)	0.34887 (18)	0.0271 (3)
H21B	−0.0415	0.4574	0.3837	0.034*
H22B	0.0448	0.3473	0.2832	0.034*
N3B	0.2716 (2)	0.39372 (18)	0.49329 (17)	0.0240 (3)
C4B	0.4678 (3)	0.3223 (2)	0.5168 (2)	0.0256 (4)
H4B	0.5206	0.3462	0.5841	0.032*
C5B	0.5789 (3)	0.2182 (2)	0.4401 (2)	0.0294 (4)
H5B	0.7148	0.1621	0.4457	0.037*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1A	0.0402 (3)	0.0267 (3)	0.0227 (2)	−0.0067 (2)	−0.0004 (2)	−0.00468 (19)
C2A	0.0265 (9)	0.0212 (9)	0.0359 (10)	−0.0024 (7)	−0.0074 (8)	−0.0073 (8)
C3A	0.0220 (8)	0.0198 (8)	0.0329 (10)	−0.0007 (7)	−0.0073 (7)	−0.0115 (7)
N4A	0.0189 (7)	0.0199 (7)	0.0216 (7)	−0.0012 (5)	−0.0053 (5)	−0.0073 (6)
C5A	0.0209 (8)	0.0242 (9)	0.0224 (8)	−0.0043 (7)	−0.0031 (6)	−0.0058 (7)
C6A	0.0225 (8)	0.0205 (8)	0.0257 (9)	−0.0028 (6)	−0.0098 (7)	−0.0051 (7)
C61A	0.0314 (10)	0.0210 (9)	0.0369 (11)	−0.0039 (7)	−0.0116 (8)	−0.0052 (8)
N7A	0.0302 (8)	0.0223 (7)	0.0232 (7)	−0.0025 (6)	−0.0080 (6)	−0.0082 (6)
C8A	0.0244 (8)	0.0230 (8)	0.0198 (8)	−0.0021 (7)	−0.0059 (7)	−0.0069 (7)
S1B	0.0291 (3)	0.0251 (3)	0.0274 (3)	0.00164 (18)	−0.00392 (18)	−0.01401 (19)
C2B	0.0247 (8)	0.0162 (8)	0.0204 (8)	−0.0027 (6)	−0.0013 (6)	−0.0065 (6)
N21B	0.0271 (8)	0.0276 (8)	0.0316 (8)	0.0007 (6)	−0.0084 (6)	−0.0176 (7)
N3B	0.0262 (8)	0.0217 (7)	0.0246 (8)	−0.0019 (6)	−0.0052 (6)	−0.0102 (6)
C4B	0.0294 (9)	0.0230 (9)	0.0238 (9)	−0.0054 (7)	−0.0069 (7)	−0.0052 (7)
C5B	0.0272 (9)	0.0271 (9)	0.0308 (10)	−0.0011 (7)	−0.0069 (7)	−0.0077 (8)

Geometric parameters (Å, º) top

S1A—C8A	1.7324 (18)	C61A—H62A	0.98
S1A—C2A	1.743 (2)	C61A—H63A	0.98
C2A—C3A	1.334 (3)	N7A—C8A	1.319 (2)
C2A—H2A	0.95	S1B—C5B	1.732 (2)
C3A—N4A	1.393 (2)	S1B—C2B	1.7518 (17)
C3A—H3A	0.95	C2B—N3B	1.312 (2)
N4A—C8A	1.363 (2)	C2B—N21B	1.345 (2)
N4A—C5A	1.381 (2)	N21B—H21B	0.88
C5A—C6A	1.368 (3)	N21B—H22B	0.88
C5A—H5A	0.95	N3B—C4B	1.391 (2)
C6A—N7A	1.388 (2)	C4B—C5B	1.340 (3)
C6A—C61A	1.495 (3)	C4B—H4B	0.95
C61A—H61A	0.98	C5B—H5B	0.95

C8A—S1A—C2A	89.74 (9)	H61A—C61A—H63A	109.5
C3A—C2A—S1A	113.09 (14)	H62A—C61A—H63A	109.5
C3A—C2A—H2A	123.5	C8A—N7A—C6A	104.09 (14)
S1A—C2A—H2A	123.5	N7A—C8A—N4A	112.88 (15)
C2A—C3A—N4A	111.98 (16)	N7A—C8A—S1A	136.17 (14)
C2A—C3A—H3A	124.0	N4A—C8A—S1A	110.93 (13)
N4A—C3A—H3A	124.0	C5B—S1B—C2B	89.06 (9)
C8A—N4A—C5A	106.52 (14)	N3B—C2B—N21B	124.61 (16)
C8A—N4A—C3A	114.26 (15)	N3B—C2B—S1B	114.35 (13)
C5A—N4A—C3A	139.17 (15)	N21B—C2B—S1B	121.04 (13)
C6A—C5A—N4A	105.51 (15)	C2B—N21B—H21B	120.0
C6A—C5A—H5A	127.2	C2B—N21B—H22B	120.0
N4A—C5A—H5A	127.2	H21B—N21B—H22B	120.0
C5A—C6A—N7A	110.99 (16)	C2B—N3B—C4B	109.87 (15)
C5A—C6A—C61A	128.64 (17)	C5B—C4B—N3B	116.87 (17)
N7A—C6A—C61A	120.35 (16)	C5B—C4B—H4B	121.6
C6A—C61A—H61A	109.5	N3B—C4B—H4B	121.6
C6A—C61A—H62A	109.5	C4B—C5B—S1B	109.85 (15)
H61A—C61A—H62A	109.5	C4B—C5B—H5B	125.1
C6A—C61A—H63A	109.5	S1B—C5B—H5B	125.1

C8A—S1A—C2A—C3A	−0.24 (15)	C3A—N4A—C8A—N7A	178.36 (14)
S1A—C2A—C3A—N4A	0.2 (2)	C5A—N4A—C8A—S1A	−178.08 (11)
C2A—C3A—N4A—C8A	0.0 (2)	C3A—N4A—C8A—S1A	−0.15 (19)
C2A—C3A—N4A—C5A	176.93 (19)	C2A—S1A—C8A—N7A	−177.8 (2)
C8A—N4A—C5A—C6A	−0.15 (18)	C2A—S1A—C8A—N4A	0.22 (14)
C3A—N4A—C5A—C6A	−177.26 (19)	C5B—S1B—C2B—N3B	−0.48 (14)
N4A—C5A—C6A—N7A	−0.16 (19)	C5B—S1B—C2B—N21B	179.75 (16)
N4A—C5A—C6A—C61A	178.67 (17)	N21B—C2B—N3B—C4B	−179.87 (17)
C5A—C6A—N7A—C8A	0.4 (2)	S1B—C2B—N3B—C4B	0.36 (19)
C61A—C6A—N7A—C8A	−178.53 (16)	C2B—N3B—C4B—C5B	0.0 (2)
C6A—N7A—C8A—N4A	−0.5 (2)	N3B—C4B—C5B—S1B	−0.4 (2)
C6A—N7A—C8A—S1A	177.48 (16)	C2B—S1B—C5B—C4B	0.45 (15)
C5A—N4A—C8A—N7A	0.4 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N21B—H21B···N3Bⁱ	0.88	2.14	3.010 (2)	170
N21B—H22B···N7A	0.88	2.10	2.933 (2)	159
C2A—H2A···N21Bⁱⁱ	0.95	2.59	3.531 (2)	174

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

Experimental details

	(I)	(II)
Crystal data
Chemical formula	C₁₀H₁₆N₂O₂S	C₆H₆N₂S·C₃H₄N₂S
M_r	228.31	238.33
Crystal system, space group	Monoclinic, P2₁/n	Triclinic, P1
Temperature (K)	120	120
a, b, c (Å)	10.6248 (8), 8.6055 (5), 13.0135 (9)	6.9195 (2), 9.1860 (2), 9.6953 (3)
α, β, γ (°)	90, 92.977 (4), 90	69.5204 (17), 71.4823 (16), 74.2770 (17)
V (Å³)	1188.24 (14)	538.48 (3)
Z	4	2
Radiation type	Mo Kα	Mo Kα
µ (mm⁻¹)	0.26	0.47
Crystal size (mm)	0.42 × 0.32 × 0.08	0.26 × 0.08 × 0.04

Data collection
Diffractometer	Bruker-Nonius KappaCCD area-detector diffractometer	Bruker-Nonius KappaCCD area-detector diffractometer
Absorption correction	Multi-scan (SORTAV; Blessing, 1995)	Multi-scan (SORTAV; Blessing, 1995)
T_min, T_max	0.913, 0.977	0.885, 0.982
No. of measured, independent and observed [I > 2σ(I)] reflections	9227, 2093, 1668	12593, 2472, 2224
R_int	0.082	0.072
(sin θ/λ)_max (Å⁻¹)	0.595	0.653

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.106, 1.08	0.040, 0.105, 1.05
No. of reflections	2093	2472
No. of parameters	140	137
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.34	0.26, −0.44

Computer programs: DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1998), DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998), DENZO and COLLECT, DENZO, SCALEPACK (Otwinowski & Minor, 1997) and COLLECT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLUTON94 (Spek, 1994) and PLATON97 (Spek, 1997), SHELXL97.

Hydrogen-bond geometry (Å, º) for (I) top

D—H···A	D—H	H···A	D···A	D—H···A
N21—H21···N3ⁱ	0.88	2.14	3.016 (2)	173
N21—H22···O51ⁱⁱ	0.88	2.02	2.858 (2)	158

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

Hydrogen-bond geometry (Å, º) for (II) top

D—H···A	D—H	H···A	D···A	D—H···A
N21B—H21B···N3Bⁱ	0.88	2.14	3.010 (2)	170
N21B—H22B···N7A	0.88	2.10	2.933 (2)	159
C2A—H2A···N21Bⁱⁱ	0.95	2.59	3.531 (2)	174

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

Acknowledgements

The authors thank the EPSRC National Crystallography Service, Southampton, England.

References

Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Blessing, R. H. (1995). Acta Cryst. A51, 33–37. CrossRef CAS Web of Science IUCr Journals Google Scholar
Caranoni, P. C. & Reboul, J. P. (1982). Acta Cryst. B38, 1255–1259. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Etter, M. C. (1990). Acc. Chem. Res. 23, 120–126. CrossRef CAS Web of Science Google Scholar
Kuz'mina, L. G. & Struchkov, Y. T. (1984). Zh. Strukt. Khim. 25, 88–92. (In Russian.) CAS Google Scholar
Lynch, D. E. & McClenaghan, I. (2002). Acta Cryst. E58, o733–o734. Web of Science CSD CrossRef IUCr Journals Google Scholar
Lynch, D. E., McClenaghan, I., Light, M. E. & Coles, S. J. (2002). Cryst. Eng. 5, 123–136. Web of Science CSD CrossRef CAS Google Scholar
Lynch, D. E., Nicholls, L. J., Smith, G., Byriel, K. A. & Kennard, C. H. L. (1999). Acta Cryst. B55, 758–766. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Merck (2001). The Merck Index, 13th ed. New York: John Wiley & Sons. Google Scholar
Moers, O., Wijaya, K., Lange, I., Blaschette, A. & Jones, P. G. (2000). Z. Naturforsch. Teil B, 55, 738–752. CAS Google Scholar
Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
Spek, A. L. (1994). PLUTON94. University of Utrecht, The Netherlands. Google Scholar
Spek, A. L. (1997). PLATON97. University of Utrecht, The Netherlands. Google Scholar
Toplak, R., Lah, N., Volmajer, J., Leban, I. & Le Maréchal, A. M. (2003). Acta Cryst. C59, o502–o505. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar

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ISSN: 2053-2296

Volume 60| Part 8| August 2004| Pages o592-o594

doi:10.1107/S0108270104015471

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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxyl­ate and 6-methylimidazo­[2,1-b]­thia­zole–2-amino-1,3-thia­zole (1/1)

Comment

Experimental

Compound (I)

Crystal data

Data collection

Refinement

Compound (II)

Crystal data

Data collection

Refinement

Supporting information

Acknowledgements

References

organic compounds

Ethyl 2-amino-4-tert-butyl-1,3-thiazole-5-carboxylate and 6-methylimidazo[2,1-b]thiazole–2-amino-1,3-thiazole (1/1)