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The title compound, C6H6N4O2S, was prepared for structural comparison with diazoxide (7-chloro-3-methyl-4H-1,2,4-benzo­thia­diazine 1,1-dioxide) and other 3-alkyl­amino­pyrido­thia­diazine 1,1-dioxides known to be potassium channel openers. Particular attention was paid to the tautomeric conformation adopted by the compound in the crystalline state, which is found to be the 4H-form.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801009904/cf6076sup1.cif
Contains datablocks I, sm0109

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801009904/cf6076Isup2.hkl
Contains datablock I

CCDC reference: 170767

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.004 Å
  • R factor = 0.032
  • wR factor = 0.090
  • Data-to-parameter ratio = 8.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Red Alert Alert Level A:
THETM_01 Alert A The value of sine(theta_max)/wavelength is less than 0.550 Calculated sin(theta_max)/wavelength = 0.5465
Author response: This should involve additional measurements. But the diffraction data were collected in 1991. The results could not be published earlier because of pharmaceutical requirements related to the hypothetical activity of the product. And now I cannot retrieve the compound to recrystallize it and to complete the measurements. I think it should be well if this study could be published because it is a rare example with the nitrogen atom in the 5-position (see the comment section above), and most of the data-validation tests are good.

Yellow Alert Alert Level C:
REFNR_01 Alert C Ratio of reflections to parameters is < 10 for a centrosymmetric structure sine(theta)/lambda 0.5465 Proportion of unique data used 1.0000 Ratio reflections to parameters 8.4141
1 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check

Comment top

Although most of the published X-ray data on pyridothiadiazine dioxides are related to compounds with the pyridinic nitrogen in the 7-position of the pyridothiadiazine ring, this example, (I), of a compound with the N atom in the 5-position will complete our information on the influence of this position on the tautomeric behavior of pyridothiadiazine dioxides. It confirms the predominance of the 4H-tautomeric form. These results may help to establish in such molecules which are the important chemical and geometrical parameters required (pharmacophore) for their biological activity.

Experimental top

The title compound was synthesized at the Laboratory of Medicinal Chemistry of Liège, according to the method of Kotovskaya et al. (1979). Cystals were obtained by slow evaporation of a methanol solution.

Refinement top

H atoms were constrained (included as riding atoms) except those on N4 and N11, which were refined, with isotropic displacement parameters fixed at 1.2Ueq of the parent atom.

Computing details top

Data collection: DIF4 (Stoe & Cie, 1987); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1.  
3-amino-4H-pyrido[2,3-e]-1,2,4-thiadiazine 1,1-dioxide top
Crystal data top
C6H6N4O2SDx = 1.657 Mg m3
Mr = 198.21Cu Kα radiation, λ = 1.54180 Å
Orthorhombic, PbcaCell parameters from 34 reflections
a = 9.7545 (6) Åθ = 24.7–40.7°
b = 12.0427 (9) ŵ = 3.43 mm1
c = 13.5242 (18) ÅT = 293 K
V = 1588.7 (3) Å3Prism, colourless
Z = 80.34 × 0.23 × 0.11 mm
F(000) = 816
Data collection top
Stoe-Siemens AED four-circle
diffractometer
829 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 57.4°, θmin = 6.6°
ω scansh = 010
Absorption correction: ψ-scan
(EMPIR; Stoe & Cie, 1987)
k = 013
Tmin = 0.388, Tmax = 0.704l = 014
1077 measured reflections2 standard reflections every 60 min
1077 independent reflections intensity decay: 3%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: H atoms were placed at standard calculated positions, except atoms H(N4) and H(N11), which were obtained from difference map.
R[F2 > 2σ(F2)] = 0.032H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.090 w = 1/[σ2(Fo2) + (0.056P)2 + 0.7861P]
where P = (Fo2 + 2Fc2)/3
S = 0.96(Δ/σ)max < 0.001
1077 reflectionsΔρmax = 0.26 e Å3
128 parametersΔρmin = 0.23 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0043 (4)
Crystal data top
C6H6N4O2SV = 1588.7 (3) Å3
Mr = 198.21Z = 8
Orthorhombic, PbcaCu Kα radiation
a = 9.7545 (6) ŵ = 3.43 mm1
b = 12.0427 (9) ÅT = 293 K
c = 13.5242 (18) Å0.34 × 0.23 × 0.11 mm
Data collection top
Stoe-Siemens AED four-circle
diffractometer
829 reflections with I > 2σ(I)
Absorption correction: ψ-scan
(EMPIR; Stoe & Cie, 1987)
Rint = 0.000
Tmin = 0.388, Tmax = 0.704θmax = 57.4°
1077 measured reflections2 standard reflections every 60 min
1077 independent reflections intensity decay: 3%
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.090H atoms treated by a mixture of independent and constrained refinement
S = 0.96Δρmax = 0.26 e Å3
1077 reflectionsΔρmin = 0.23 e Å3
128 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
S10.25128 (6)0.15663 (5)0.15784 (4)0.0349 (3)
N20.2634 (2)0.23379 (17)0.06191 (16)0.0375 (6)
C30.3872 (2)0.2671 (2)0.03169 (17)0.0342 (6)
N40.5058 (2)0.21512 (17)0.05706 (17)0.0365 (6)
H40.579 (3)0.233 (2)0.0290 (19)0.044*
C50.5073 (2)0.1097 (2)0.10053 (17)0.0327 (6)
N60.6239 (2)0.05258 (17)0.09079 (14)0.0362 (5)
C70.6238 (3)0.0509 (2)0.12950 (19)0.0390 (6)
H70.70440.09190.12550.047*
C80.5124 (3)0.0996 (2)0.17444 (19)0.0417 (7)
H80.51770.17170.19880.050*
C90.3936 (3)0.0398 (2)0.18253 (19)0.0399 (6)
H90.31580.07100.21100.048*
C100.3920 (3)0.06849 (19)0.14730 (17)0.0323 (6)
N110.3949 (3)0.35321 (18)0.02874 (18)0.0446 (6)
H1110.316 (3)0.381 (2)0.044 (2)0.054*
H1120.474 (3)0.369 (2)0.063 (2)0.054*
O10.12740 (19)0.09326 (15)0.14953 (14)0.0489 (5)
O20.26608 (18)0.21993 (15)0.24652 (13)0.0471 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0324 (4)0.0353 (4)0.0369 (4)0.0001 (3)0.0012 (3)0.0056 (3)
N20.0336 (11)0.0383 (12)0.0406 (12)0.0034 (10)0.0021 (10)0.0110 (10)
C30.0324 (13)0.0344 (13)0.0357 (13)0.0016 (12)0.0001 (11)0.0011 (12)
N40.0325 (12)0.0343 (12)0.0426 (13)0.0029 (9)0.0013 (10)0.0065 (11)
C50.0356 (14)0.0319 (14)0.0306 (13)0.0020 (11)0.0055 (11)0.0037 (11)
N60.0351 (12)0.0366 (12)0.0368 (13)0.0026 (10)0.0053 (9)0.0015 (9)
C70.0438 (15)0.0353 (14)0.0379 (14)0.0095 (13)0.0095 (12)0.0052 (11)
C80.0500 (17)0.0325 (14)0.0425 (15)0.0005 (12)0.0039 (13)0.0014 (12)
C90.0431 (15)0.0353 (13)0.0411 (15)0.0029 (13)0.0004 (12)0.0067 (12)
C100.0338 (14)0.0322 (13)0.0311 (13)0.0012 (11)0.0036 (10)0.0020 (10)
N110.0356 (13)0.0431 (14)0.0552 (15)0.0048 (11)0.0055 (11)0.0190 (11)
O10.0344 (10)0.0504 (11)0.0620 (13)0.0066 (9)0.0048 (8)0.0180 (9)
O20.0537 (11)0.0494 (10)0.0382 (10)0.0061 (9)0.0043 (9)0.0031 (10)
Geometric parameters (Å, º) top
S1—O21.4285 (19)C5—C101.382 (3)
S1—O11.4336 (19)N6—C71.351 (3)
S1—N21.600 (2)C7—C81.377 (4)
S1—C101.741 (2)C7—H70.930
N2—C31.336 (3)C8—C91.369 (4)
C3—N111.323 (3)C8—H80.930
C3—N41.359 (3)C9—C101.389 (4)
N4—C51.399 (3)C9—H90.930
N4—H40.84 (3)N11—H1110.86 (3)
C5—N61.335 (3)N11—H1120.92 (3)
O2—S1—O1115.79 (12)C5—N6—C7115.9 (2)
O2—S1—N2111.31 (12)N6—C7—C8124.4 (2)
O1—S1—N2107.94 (11)N6—C7—H7117.8
O2—S1—C10108.32 (11)C8—C7—H7117.8
O1—S1—C10109.49 (12)C9—C8—C7118.6 (2)
N2—S1—C10103.25 (11)C9—C8—H8120.7
C3—N2—S1119.27 (16)C7—C8—H8120.7
N11—C3—N2118.4 (2)C8—C9—C10118.5 (2)
N11—C3—N4117.9 (2)C8—C9—H9120.8
N2—C3—N4123.6 (2)C10—C9—H9120.8
C3—N4—C5122.2 (2)C5—C10—C9119.0 (2)
C3—N4—H4119.4 (19)C5—C10—S1117.40 (18)
C5—N4—H4115 (2)C9—C10—S1123.6 (2)
N6—C5—C10123.6 (2)C3—N11—H111114 (2)
N6—C5—N4115.8 (2)C3—N11—H112121.3 (19)
C10—C5—N4120.6 (2)H111—N11—H112123 (3)
O2—S1—N2—C377.8 (2)C7—C8—C9—C101.7 (4)
O1—S1—N2—C3154.1 (2)N6—C5—C10—C93.1 (4)
C10—S1—N2—C338.2 (2)N4—C5—C10—C9174.8 (2)
S1—N2—C3—N11161.57 (19)N6—C5—C10—S1177.35 (18)
S1—N2—C3—N420.6 (3)N4—C5—C10—S14.8 (3)
N11—C3—N4—C5164.7 (2)C8—C9—C10—C53.6 (4)
N2—C3—N4—C513.2 (4)C8—C9—C10—S1176.82 (19)
C3—N4—C5—N6157.7 (2)O2—S1—C10—C587.7 (2)
C3—N4—C5—C1020.3 (4)O1—S1—C10—C5145.21 (19)
C10—C5—N6—C70.3 (3)N2—S1—C10—C530.4 (2)
N4—C5—N6—C7177.6 (2)O2—S1—C10—C992.8 (2)
C5—N6—C7—C81.8 (4)O1—S1—C10—C934.4 (2)
N6—C7—C8—C91.1 (4)N2—S1—C10—C9149.1 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4···N2i0.84 (3)2.22 (3)3.047 (3)172 (3)
N11—H112···O1i0.92 (3)1.96 (3)2.868 (3)173 (3)
N11—H111···N6ii0.86 (3)2.13 (3)2.997 (3)177 (3)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formulaC6H6N4O2S
Mr198.21
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)293
a, b, c (Å)9.7545 (6), 12.0427 (9), 13.5242 (18)
V3)1588.7 (3)
Z8
Radiation typeCu Kα
µ (mm1)3.43
Crystal size (mm)0.34 × 0.23 × 0.11
Data collection
DiffractometerStoe-Siemens AED four-circle
diffractometer
Absorption correctionψ-scan
(EMPIR; Stoe & Cie, 1987)
Tmin, Tmax0.388, 0.704
No. of measured, independent and
observed [I > 2σ(I)] reflections
1077, 1077, 829
Rint0.000
θmax (°)57.4
(sin θ/λ)max1)0.546
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.090, 0.96
No. of reflections1077
No. of parameters128
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.26, 0.23

Computer programs: DIF4 (Stoe & Cie, 1987), DIF4, REDU4 (Stoe & Cie, 1987), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996), SHELXL97.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H4···N2i0.84 (3)2.22 (3)3.047 (3)172 (3)
N11—H112···O1i0.92 (3)1.96 (3)2.868 (3)173 (3)
N11—H111···N6ii0.86 (3)2.13 (3)2.997 (3)177 (3)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x1/2, y+1/2, z.
 

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