Unexpected formation of a thia­zolo[3,2-a]pyridinium methide: a novel subclass of mesoionic compounds

While trying to prepare mesoionic thia­zolo[3,2-a]pyridinium-2-thiol­ate by reaction of 2-bromo-1-(ethoxy­carbonyl­meth­yl)pyridinium bromide with CS₂, an unexpected product was formed, namely (ethoxy­carbon­yl)[3-(ethoxy­carbon­yl)-1,3-thia­­zolo[3,2-a]pyridin-4-ium-2-­yl](2-thioxo-1,2-dihydro­pyridin-1-yl)methanide, C₁₉H₁₈N₂O₄S₂. The structure of the product corresponds to a previously unknown subclass of mesoionic thia­zolo[3,2-a]pyridinium-2-methyl­ides.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.032
• wR factor = 0.077
• Data-to-parameter ratio = 17.5

checkCIF/PLATON results

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Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

(ethoxycarbonyl)[3-(ethoxycarbonyl)-1,3-thiazolo[3,2-a]pyridin-4-ium-2- yl](2-thioxo-1,2-dihydropyridin-1-yl)methanide

Crystal data

C19H18N2O4S2	Z = 2
Mr = 402.47	F(000) = 420
Triclinic, P1	Dx = 1.508 Mg m^−3
Hall symbol: -P 1	Melting point: 465 K
a = 6.8600 (14) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.0710 (18) Å	Cell parameters from 6851 reflections
c = 14.634 (3) Å	θ = 3.5–31°
α = 82.66 (3)°	µ = 0.33 mm^−1
β = 80.06 (3)°	T = 100 K
γ = 84.11 (3)°	Plate, dark-red
V = 886.6 (3) Å^3	0.40 × 0.40 × 0.14 mm

Data collection

Stoe IPDS diffractometer	3810 reflections with I > 2σ(I)
Radiation source: Fine-focus sealed tube	Rint = 0.020
Graphite monochromator	θmax = 29.1°, θmin = 3.4°
ω scans	h = −8→9
6851 measured reflections	k = −12→12
4780 independent reflections	l = −20→20

Refinement

Refinement on F^2	Primary atom site location: Direct
Least-squares matrix: Full	Secondary atom site location: Difmap
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: Geom
wR(F^2) = 0.077	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0359P)^2 + 0.5422P] where P = (Fo^2 + 2Fc^2)/3
4308 reflections	(Δ/σ)max = 0.002
246 parameters	Δρmax = 0.46 e Å^−3
0 restraints	Δρmin = −0.29 e Å^−3

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

	x	y	z	Uiso*/Ueq
N1	0.73931 (17)	0.06684 (12)	0.43307 (7)	0.0117 (2)
C2	0.7116 (2)	0.17442 (14)	0.35650 (8)	0.0118 (2)
C3	0.71296 (19)	0.10997 (13)	0.27377 (8)	0.0103 (2)
S4	0.72642 (5)	−0.08644 (3)	0.29787 (2)	0.01191 (8)
C5	0.7457 (2)	−0.07683 (14)	0.41281 (9)	0.0123 (2)
C6	0.7664 (2)	−0.19789 (15)	0.48086 (9)	0.0158 (3)
H6	0.7701	−0.2970	0.4657	0.019*
C7	0.7814 (2)	−0.17233 (16)	0.57020 (9)	0.0171 (3)
H7	0.7968	−0.2531	0.6173	0.021*
C8	0.7736 (2)	−0.02521 (16)	0.58988 (9)	0.0164 (3)
H8	0.7826	−0.0060	0.6513	0.020*
C9	0.7531 (2)	0.09251 (15)	0.52230 (9)	0.0144 (3)
H9	0.7484	0.1919	0.5372	0.017*
C10	0.7207 (2)	0.17242 (13)	0.18132 (8)	0.0109 (2)
C11	0.71795 (19)	0.07723 (13)	0.11059 (8)	0.0107 (2)
O11	0.69820 (15)	−0.05712 (10)	0.12827 (6)	0.01452 (19)
O12	0.74345 (15)	0.14595 (10)	0.02199 (6)	0.01253 (19)
C13	0.7638 (2)	0.04543 (13)	−0.04991 (8)	0.0122 (2)
H13A	0.6475	−0.0143	−0.0398	0.015*
H13B	0.8849	−0.0236	−0.0477	0.015*
C14	0.7777 (2)	0.13942 (15)	−0.14321 (9)	0.0166 (3)
H14A	0.6575	0.2076	−0.1445	0.025*
H14B	0.7906	0.0745	−0.1929	0.025*
H14C	0.8941	0.1972	−0.1528	0.025*
C15	0.6679 (2)	0.33087 (14)	0.37343 (9)	0.0144 (3)
O15	0.7262 (2)	0.38675 (12)	0.43391 (8)	0.0270 (3)
O16	0.54618 (16)	0.40277 (10)	0.31738 (7)	0.0161 (2)
C17	0.4825 (2)	0.55892 (14)	0.32733 (10)	0.0203 (3)
H17A	0.5449	0.6233	0.2725	0.024*
H17B	0.5225	0.5875	0.3841	0.024*
C18	0.2601 (3)	0.57815 (16)	0.33466 (11)	0.0234 (3)
H18A	0.2204	0.5324	0.2843	0.035*
H18B	0.2160	0.6847	0.3293	0.035*
H18C	0.1991	0.5299	0.3951	0.035*
N19	0.76306 (17)	0.32462 (11)	0.15110 (7)	0.0108 (2)
C20	0.9490 (2)	0.37005 (13)	0.15285 (8)	0.0115 (2)
S20	1.13386 (5)	0.25380 (3)	0.19116 (2)	0.01423 (8)
C21	0.9756 (2)	0.52220 (14)	0.11827 (9)	0.0151 (3)
H21	1.0980	0.5607	0.1208	0.018*
C22	0.8313 (2)	0.61450 (14)	0.08165 (9)	0.0174 (3)
H22	0.8550	0.7147	0.0580	0.021*
C23	0.6475 (2)	0.56066 (15)	0.07906 (9)	0.0171 (3)
H23	0.5467	0.6229	0.0527	0.021*
C24	0.6171 (2)	0.41725 (14)	0.11514 (9)	0.0139 (2)
H24	0.4921	0.3806	0.1154	0.017*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0112 (5)	0.0138 (5)	0.0100 (5)	−0.0027 (4)	−0.0006 (4)	−0.0016 (4)
C2	0.0146 (6)	0.0117 (5)	0.0092 (5)	−0.0028 (4)	−0.0009 (5)	−0.0012 (4)
C3	0.0097 (6)	0.0097 (5)	0.0119 (5)	−0.0023 (4)	−0.0007 (4)	−0.0024 (4)
S4	0.01615 (17)	0.00926 (13)	0.01042 (14)	−0.00289 (10)	−0.00121 (11)	−0.00123 (10)
C5	0.0118 (6)	0.0130 (5)	0.0119 (5)	−0.0027 (4)	−0.0005 (5)	−0.0013 (4)
C6	0.0160 (7)	0.0151 (6)	0.0160 (6)	−0.0041 (5)	−0.0029 (5)	0.0020 (5)
C7	0.0150 (7)	0.0212 (6)	0.0143 (6)	−0.0038 (5)	−0.0034 (5)	0.0040 (5)
C8	0.0134 (7)	0.0248 (7)	0.0110 (5)	−0.0033 (5)	−0.0021 (5)	−0.0009 (5)
C9	0.0135 (7)	0.0198 (6)	0.0104 (5)	−0.0022 (5)	−0.0015 (5)	−0.0036 (4)
C10	0.0137 (6)	0.0086 (5)	0.0109 (5)	−0.0025 (4)	−0.0010 (5)	−0.0025 (4)
C11	0.0101 (6)	0.0119 (5)	0.0104 (5)	−0.0012 (4)	−0.0017 (4)	−0.0025 (4)
O11	0.0196 (5)	0.0107 (4)	0.0141 (4)	−0.0037 (3)	−0.0026 (4)	−0.0030 (3)
O12	0.0188 (5)	0.0107 (4)	0.0088 (4)	−0.0016 (3)	−0.0023 (4)	−0.0033 (3)
C13	0.0156 (6)	0.0114 (5)	0.0106 (5)	−0.0014 (4)	−0.0019 (5)	−0.0050 (4)
C14	0.0241 (8)	0.0144 (6)	0.0110 (5)	0.0000 (5)	−0.0020 (5)	−0.0030 (4)
C15	0.0186 (7)	0.0137 (5)	0.0108 (5)	−0.0033 (5)	0.0001 (5)	−0.0030 (4)
O15	0.0479 (8)	0.0165 (5)	0.0219 (5)	−0.0020 (5)	−0.0170 (5)	−0.0072 (4)
O16	0.0225 (5)	0.0097 (4)	0.0173 (4)	0.0013 (3)	−0.0051 (4)	−0.0055 (3)
C17	0.0326 (9)	0.0090 (5)	0.0198 (6)	0.0004 (5)	−0.0041 (6)	−0.0054 (5)
C18	0.0327 (9)	0.0168 (6)	0.0213 (7)	0.0071 (6)	−0.0089 (6)	−0.0057 (5)
N19	0.0144 (6)	0.0089 (4)	0.0094 (4)	−0.0017 (4)	−0.0013 (4)	−0.0023 (3)
C20	0.0146 (6)	0.0112 (5)	0.0092 (5)	−0.0027 (4)	−0.0008 (5)	−0.0033 (4)
S20	0.01343 (17)	0.01290 (14)	0.01683 (15)	−0.00174 (11)	−0.00421 (12)	−0.00047 (11)
C21	0.0195 (7)	0.0112 (5)	0.0151 (6)	−0.0048 (5)	−0.0016 (5)	−0.0026 (4)
C22	0.0265 (8)	0.0101 (5)	0.0153 (6)	−0.0019 (5)	−0.0018 (5)	−0.0020 (4)
C23	0.0225 (7)	0.0133 (6)	0.0151 (6)	0.0039 (5)	−0.0045 (5)	−0.0018 (4)
C24	0.0149 (7)	0.0146 (6)	0.0128 (5)	0.0003 (4)	−0.0034 (5)	−0.0033 (4)

Geometric parameters (Å, º)

N1—C5	1.3677 (16)	C14—H14A	0.9800
N1—C9	1.3758 (16)	C14—H14B	0.9800
N1—C2	1.4143 (17)	C14—H14C	0.9800
C2—C3	1.4082 (17)	C15—O15	1.2160 (17)
C2—C15	1.4636 (17)	C15—O16	1.3356 (18)
C3—C10	1.3928 (17)	O16—C17	1.4567 (16)
C3—S4	1.7675 (13)	C17—C18	1.504 (2)
S4—C5	1.7237 (14)	C17—H17A	0.9900
C5—C6	1.3983 (18)	C17—H17B	0.9900
C6—C7	1.3793 (19)	C18—H18A	0.9800
C6—H6	0.9500	C18—H18B	0.9800
C7—C8	1.395 (2)	C18—H18C	0.9800
C7—H7	0.9500	N19—C24	1.3717 (18)
C8—C9	1.373 (2)	N19—C20	1.3852 (17)
C8—H8	0.9500	C20—C21	1.4268 (17)
C9—H9	0.9500	C20—S20	1.6897 (15)
C10—C11	1.4337 (17)	C21—C22	1.366 (2)
C10—N19	1.4381 (15)	C21—H21	0.9500
C11—O11	1.2295 (15)	C22—C23	1.406 (2)
C11—O12	1.3557 (15)	C22—H22	0.9500
O12—C13	1.4581 (14)	C23—C24	1.3626 (19)
C13—C14	1.5081 (18)	C23—H23	0.9500
C13—H13A	0.9900	C24—H24	0.9500
C13—H13B	0.9900
C5—N1—C9	119.24 (11)	C13—C14—H14B	109.5
C5—N1—C2	113.37 (11)	H14A—C14—H14B	109.5
C9—N1—C2	127.35 (11)	C13—C14—H14C	109.5
C3—C2—N1	112.66 (11)	H14A—C14—H14C	109.5
C3—C2—C15	128.68 (12)	H14B—C14—H14C	109.5
N1—C2—C15	118.38 (11)	O15—C15—O16	124.07 (12)
C10—C3—C2	131.70 (11)	O15—C15—C2	124.55 (13)
C10—C3—S4	118.39 (9)	O16—C15—C2	111.28 (11)
C2—C3—S4	109.70 (9)	C15—O16—C17	118.33 (11)
C5—S4—C3	91.55 (7)	O16—C17—C18	107.97 (12)
N1—C5—C6	121.32 (12)	O16—C17—H17A	110.1
N1—C5—S4	112.47 (10)	C18—C17—H17A	110.1
C6—C5—S4	126.20 (10)	O16—C17—H17B	110.1
C7—C6—C5	119.50 (12)	C18—C17—H17B	110.1
C7—C6—H6	120.3	H17A—C17—H17B	108.4
C5—C6—H6	120.3	C17—C18—H18A	109.5
C6—C7—C8	118.49 (13)	C17—C18—H18B	109.5
C6—C7—H7	120.8	H18A—C18—H18B	109.5
C8—C7—H7	120.8	C17—C18—H18C	109.5
C9—C8—C7	121.33 (13)	H18A—C18—H18C	109.5
C9—C8—H8	119.3	H18B—C18—H18C	109.5
C7—C8—H8	119.3	C24—N19—C20	122.52 (11)
C8—C9—N1	120.12 (12)	C24—N19—C10	116.97 (11)
C8—C9—H9	119.9	C20—N19—C10	120.35 (11)
N1—C9—H9	119.9	N19—C20—C21	115.31 (12)
C3—C10—C11	119.18 (11)	N19—C20—S20	122.81 (9)
C3—C10—N19	122.55 (11)	C21—C20—S20	121.88 (11)
C11—C10—N19	117.51 (11)	C22—C21—C20	122.31 (13)
O11—C11—O12	122.22 (11)	C22—C21—H21	118.8
O11—C11—C10	122.90 (12)	C20—C21—H21	118.8
O12—C11—C10	114.87 (10)	C21—C22—C23	119.75 (12)
C11—O12—C13	114.42 (9)	C21—C22—H22	120.1
O12—C13—C14	107.74 (10)	C23—C22—H22	120.1
O12—C13—H13A	110.2	C24—C23—C22	118.59 (13)
C14—C13—H13A	110.2	C24—C23—H23	120.7
O12—C13—H13B	110.2	C22—C23—H23	120.7
C14—C13—H13B	110.2	C23—C24—N19	121.43 (13)
H13A—C13—H13B	108.5	C23—C24—H24	119.3
C13—C14—H14A	109.5	N19—C24—H24	119.3
C5—N1—C2—C3	−4.91 (16)	N19—C10—C11—O11	174.38 (12)
C9—N1—C2—C3	177.33 (12)	C3—C10—C11—O12	−174.49 (12)
C5—N1—C2—C15	169.58 (12)	N19—C10—C11—O12	−4.18 (18)
C9—N1—C2—C15	−8.2 (2)	O11—C11—O12—C13	−5.43 (18)
N1—C2—C3—C10	−169.10 (14)	C10—C11—O12—C13	173.14 (11)
C15—C2—C3—C10	17.1 (2)	C11—O12—C13—C14	176.47 (11)
N1—C2—C3—S4	5.39 (14)	C3—C2—C15—O15	−156.16 (15)
C15—C2—C3—S4	−168.39 (12)	N1—C2—C15—O15	30.4 (2)
C10—C3—S4—C5	171.73 (12)	C3—C2—C15—O16	27.39 (19)
C2—C3—S4—C5	−3.60 (10)	N1—C2—C15—O16	−146.08 (12)
C9—N1—C5—C6	−0.2 (2)	O15—C15—O16—C17	1.6 (2)
C2—N1—C5—C6	−178.12 (12)	C2—C15—O16—C17	178.04 (11)
C9—N1—C5—S4	−179.99 (10)	C15—O16—C17—C18	−129.94 (13)
C2—N1—C5—S4	2.05 (14)	C3—C10—N19—C24	−117.42 (14)
C3—S4—C5—N1	0.92 (10)	C11—C10—N19—C24	72.62 (15)
C3—S4—C5—C6	−178.90 (13)	C3—C10—N19—C20	66.97 (17)
N1—C5—C6—C7	−0.2 (2)	C11—C10—N19—C20	−102.99 (14)
S4—C5—C6—C7	179.57 (11)	C24—N19—C20—C21	2.59 (17)
C5—C6—C7—C8	0.6 (2)	C10—N19—C20—C21	177.95 (10)
C6—C7—C8—C9	−0.5 (2)	C24—N19—C20—S20	−176.29 (9)
C7—C8—C9—N1	0.2 (2)	C10—N19—C20—S20	−0.94 (16)
C5—N1—C9—C8	0.2 (2)	N19—C20—C21—C22	−3.16 (18)
C2—N1—C9—C8	177.84 (13)	S20—C20—C21—C22	175.74 (10)
C2—C3—C10—C11	−179.37 (14)	C20—C21—C22—C23	1.3 (2)
S4—C3—C10—C11	6.53 (18)	C21—C22—C23—C24	1.23 (19)
C2—C3—C10—N19	10.8 (2)	C22—C23—C24—N19	−1.82 (19)
S4—C3—C10—N19	−163.27 (10)	C20—N19—C24—C23	−0.19 (18)
C3—C10—C11—O11	4.1 (2)	C10—N19—C24—C23	−175.69 (11)