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The title compound, C6H7NS, is planar, with endo-C-N-C bond angles of 118.7 (2) and 118.8 (2)°, and C-S bond lengths of 1.697 (2) and 1.692 (2) Å for the two symmetrically independent mol­ecules. 1-Methylpyridinium-4-thiol­ate is the major contributor to the molecular structure in the solid state.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101018029/gg1079sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101018029/gg1079Isup2.hkl
Contains datablock I

CCDC reference: 180164

Comment top

Insight into the nature of the thiocarbonyl group in thiolactams is important, i.e. for the evaluation of biological significance of pyrimidinethiones and pyrimidine-dithiones as rare-bases in RNA or purinethiones (e.g. thioguanine) as anticancer drugs (Reynolds, 1989). The synthetic application of thiolactams also seems to depend on their structural features. Due to electronic interactions expressed by mesomerism of the thiocarbonyl group in thioamides: the length of carbon sulfur bonds in thioamides are a little longer than those in thiones (Rozsondai, 1993) and vary from 1.622 (2) Å in thiocarbonylo-1,1'-bis(2-methylbenzimidazole) (II) (Dolling et al., 1995) to 1.692 (2) or 1.698 (2) Å in 2(1H)-pyridinethione (III) (Ohms et al., 1982), or from 1.677 (3) Å up to 1.691 (4) Å for 3-substituted 1-methyl-2(1H)-pyridinethiones (IVa,b) (Dupont et al., 1983, Dupont et al., 1984). γ-azinethiones can be considered as vinylogous analogs of thiolactams. Several papers deal with the study on dibenzo- and benzo-γ-pyridinethiones, i.e. on derivatives of 9(10H)-acridinethione (VI) (Jaud et al., 1995) or 4(1H)-quinolinethione (V) (Maślankiewicz et al., 1998), respectively. This paper presents the data for the parent γ-pyridinethione as exemplified by the title 1-methyl-4(1H)-pyridinethione (I).

The atom-numbering scheme is shown in the ORTEPII drawing in Fig. 1 (Johnson, 1976) with selected bond lengths and angles are given in Table 1. There are two symmetrically independent molecules in the unit cell which exhibit similar values of bond lengths and angles at the 2σ level. The pyridine rings of (I) are planar for both independent molecules (r.m.s. deviations of the ring atoms are 0.004 (3) and 0.005 (3) Å for molecules A and B, respectively); exo-substituents S41A, C11A and S41B are in plane of the appropriate rings within 3σ except for C11B which deviates out of the plane by 0.030 (4) Å. The two planar molecules are inclined by the angle 67.75 (7)°. There is one intermolecular C—H···π interaction between molecules A and B, C5B—H5B···(N1A/C2A/C3A/C4A/C5A/C6A)i and a H···Cg distance of 2.69 Å where Cg1 is the aromatic ring centroid and symmetry operator (i) = -1 - x,2y,1 - z.

The most interesting molecular feature of (I) is the planarity around the endocyclic-N atom indicating sp2 hybridization of the N1 atom. Thus, the planar tricoordinated N1 atom should bear a positive charge and, furthermore, a pyridinium-type resonance form (Ia) should be the major contributor to the true molecular structure of (I).

It is well known (Witanowski et al., 1973) that a N atom bearing a formal positive charge tends to produce a relatively sharp 14N NMR signal. In fact the 14N NMR spectrum (in CDCl3 solution) of the title compound 1-methyl-4(1H)-pyridinethione (I) reveals an N atom signal at δ = -220 p.p.m. with half-height of linewidths Δν1/2 = 286 Hz (Zi\,eba & Maślankiewicz, 1996). It has led us to the conclusion that for compound (I), a pyridinium-type resonance form (Ia) is the major contributor to the real molecular structure of (I). The occurrence of a positively charged endocyclic N atom should be accompanied by elongation of the C–S bond of the thiocarbonyl group as shown in formula (Ia). However, the value of the the endocyclic C–N–C bond angle of 118.7 (2) and 118.8 (2)° in (I) is below the generally accepted limit (120°) (Pauling, 1960) for the endocyclic C–N–C bond angle in pyridinium salts.

Experimental top

Compound (1) was synthesized and purified by the method of Albert & Barlin (1959). Single crystals suitable for X-ray data collection were obtained on slow evaporation from a ethyl acetate solution.

Refinement top

The H atoms were treated as riding atoms using the SHELXL97 (Sheldrick, 1997) defaults, d(C—H) = 0.93 Å for the aromatic and 0.96 Å for methyl-H atoms.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software (Enraf-Nonius, 1989); data reduction: SDP (B. A. Frenz & Associates Inc., 1985); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1]
SCHEME 1

SCHEME 2

Fig. 1. Molecular structures of the two symmetrically independent molecules of compound (I) at the 50% probability level (Farrugia, 1997).

SCHEME 3
'1-Methyl-4(1H)-pyridinethione' top
Crystal data top
C6H7NSZ = 4
Mr = 125.19F(000) = 264
Triclinic, P1Dx = 1.312 Mg m3
a = 7.544 (1) ÅCu Kα radiation, λ = 1.54178 Å
b = 9.085 (1) ÅCell parameters from 25 reflections
c = 9.302 (1) Åθ = 7–19°
α = 89.84 (1)°µ = 3.59 mm1
β = 84.03 (1)°T = 293 K
γ = 87.98 (1)°Block, yellow
V = 633.7 (1) Å30.32 × 0.28 × 0.26 mm
Data collection top
Enraf-Nonius CAD4
diffractometer
Rint = 0.022
Radiation source: fine-focus sealed tubeθmax = 78.2°, θmin = 4.8°
Graphite monochromatorh = 09
ω–2θ scansk = 1111
2861 measured reflectionsl = 1111
2654 independent reflections3 standard reflections every 60 min
2012 reflections with I > 2σ(I) intensity decay: <1%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.135 w = 1/[σ2(Fo2) + (0.0893P)2 + 0.0559P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.018
2654 reflectionsΔρmax = 0.47 e Å3
148 parametersΔρmin = 0.37 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.012 (2)
Crystal data top
C6H7NSγ = 87.98 (1)°
Mr = 125.19V = 633.7 (1) Å3
Triclinic, P1Z = 4
a = 7.544 (1) ÅCu Kα radiation
b = 9.085 (1) ŵ = 3.59 mm1
c = 9.302 (1) ÅT = 293 K
α = 89.84 (1)°0.32 × 0.28 × 0.26 mm
β = 84.03 (1)°
Data collection top
Enraf-Nonius CAD4
diffractometer
Rint = 0.022
2861 measured reflections3 standard reflections every 60 min
2654 independent reflections intensity decay: <1%
2012 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.135H-atom parameters constrained
S = 1.04Δρmax = 0.47 e Å3
2654 reflectionsΔρmin = 0.37 e Å3
148 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
N1A0.2188 (2)0.64031 (19)0.38365 (18)0.0449 (4)
C2A0.0653 (3)0.6837 (2)0.4314 (2)0.0474 (5)
H2A0.07080.74900.50870.057*
C3A0.0951 (3)0.6346 (2)0.3697 (2)0.0471 (4)
H3A0.19740.66650.40610.057*
C4A0.1131 (3)0.5359 (2)0.2512 (2)0.0429 (4)
C5A0.0512 (3)0.4955 (2)0.2038 (2)0.0522 (5)
H5A0.05030.43180.12560.063*
C6A0.2091 (3)0.5474 (2)0.2697 (3)0.0532 (5)
H6A0.31410.51830.23560.064*
S41A0.31282 (8)0.47185 (6)0.17014 (7)0.0587 (2)
C11A0.3913 (3)0.6968 (3)0.4530 (3)0.0637 (6)
H11A0.48560.66020.40280.095*
H11B0.39510.80250.44980.095*
H11C0.40620.66480.55190.095*
N1B0.7288 (2)0.9911 (2)1.10807 (17)0.0470 (4)
C2B0.6816 (3)0.8587 (2)1.0474 (2)0.0512 (5)
H2B0.63890.78391.10440.061*
C3B0.6946 (3)0.8321 (2)0.9061 (2)0.0512 (5)
H3B0.65830.74010.86800.061*
C4B0.7621 (3)0.9408 (2)0.8143 (2)0.0435 (4)
C5B0.8102 (3)1.0766 (2)0.8837 (2)0.0494 (5)
H5B0.85571.15310.83040.059*
C6B0.7923 (3)1.0991 (2)1.0248 (2)0.0505 (5)
H6B0.82441.19081.06570.061*
S41B0.78108 (9)0.91137 (8)0.63710 (6)0.0669 (2)
C11B0.7161 (4)1.0181 (4)1.2623 (2)0.0708 (7)
H11D0.82871.00051.31640.106*
H11E0.68521.11841.27580.106*
H11F0.62590.95311.29560.106*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N1A0.0404 (9)0.0451 (8)0.0498 (9)0.0043 (7)0.0076 (7)0.0022 (7)
C2A0.0496 (11)0.0475 (10)0.0469 (10)0.0056 (8)0.0125 (8)0.0079 (8)
C3A0.0440 (10)0.0464 (10)0.0534 (10)0.0059 (8)0.0149 (8)0.0066 (8)
C4A0.0429 (10)0.0363 (8)0.0510 (10)0.0043 (7)0.0107 (8)0.0003 (7)
C5A0.0494 (12)0.0508 (10)0.0586 (12)0.0065 (9)0.0138 (9)0.0164 (9)
C6A0.0447 (11)0.0547 (11)0.0631 (12)0.0091 (9)0.0161 (9)0.0116 (9)
S41A0.0464 (3)0.0529 (3)0.0766 (4)0.0024 (2)0.0067 (2)0.0151 (2)
C11A0.0464 (12)0.0706 (15)0.0726 (15)0.0004 (11)0.0000 (10)0.0113 (12)
N1B0.0467 (9)0.0561 (10)0.0389 (8)0.0082 (7)0.0058 (7)0.0029 (7)
C2B0.0515 (12)0.0478 (10)0.0553 (11)0.0024 (9)0.0102 (9)0.0078 (9)
C3B0.0542 (12)0.0382 (9)0.0609 (12)0.0005 (8)0.0059 (9)0.0084 (8)
C4B0.0411 (10)0.0477 (10)0.0419 (9)0.0083 (8)0.0038 (7)0.0060 (7)
C5B0.0590 (12)0.0409 (9)0.0485 (10)0.0002 (9)0.0074 (9)0.0022 (8)
C6B0.0587 (12)0.0420 (9)0.0502 (11)0.0028 (9)0.0027 (9)0.0090 (8)
S41B0.0719 (4)0.0870 (5)0.0437 (3)0.0132 (3)0.0108 (2)0.0170 (3)
C11B0.0709 (16)0.102 (2)0.0407 (11)0.0151 (15)0.0086 (10)0.0077 (12)
Geometric parameters (Å, º) top
N1A—C6A1.351 (3)N1B—C2B1.351 (3)
N1A—C2A1.354 (3)N1B—C6B1.353 (3)
N1A—C11A1.468 (3)N1B—C11B1.470 (3)
C2A—C3A1.346 (3)C2B—C3B1.351 (3)
C2A—H2A0.9300C2B—H2B0.9300
C3A—C4A1.415 (3)C3B—C4B1.419 (3)
C3A—H3A0.9300C3B—H3B0.9300
C4A—C5A1.418 (3)C4B—C5B1.412 (3)
C4A—S41A1.697 (2)C4B—S41B1.6922 (19)
C5A—C6A1.352 (3)C5B—C6B1.350 (3)
C5A—H5A0.9300C5B—H5B0.9300
C6A—H6A0.9300C6B—H6B0.9300
C11A—H11A0.9600C11B—H11D0.9600
C11A—H11B0.9600C11B—H11E0.9600
C11A—H11C0.9600C11B—H11F0.9600
C6A—N1A—C2A118.71 (19)C2B—N1B—C6B118.80 (17)
C6A—N1A—C11A121.21 (19)C2B—N1B—C11B121.2 (2)
C2A—N1A—C11A120.07 (19)C6B—N1B—C11B120.0 (2)
C3A—C2A—N1A121.57 (18)N1B—C2B—C3B121.77 (19)
C3A—C2A—H2A119.2N1B—C2B—H2B119.1
N1A—C2A—H2A119.2C3B—C2B—H2B119.1
C2A—C3A—C4A122.11 (18)C2B—C3B—C4B121.76 (19)
C2A—C3A—H3A118.9C2B—C3B—H3B119.1
C4A—C3A—H3A118.9C4B—C3B—H3B119.1
C3A—C4A—C5A114.18 (19)C5B—C4B—C3B113.95 (18)
C3A—C4A—S41A123.53 (16)C5B—C4B—S41B122.90 (16)
C5A—C4A—S41A122.29 (15)C3B—C4B—S41B123.14 (15)
C6A—C5A—C4A121.52 (19)C6B—C5B—C4B122.29 (19)
C6A—C5A—H5A119.2C6B—C5B—H5B118.9
C4A—C5A—H5A119.2C4B—C5B—H5B118.9
N1A—C6A—C5A121.90 (19)C5B—C6B—N1B121.40 (18)
N1A—C6A—H6A119.1C5B—C6B—H6B119.3
C5A—C6A—H6A119.1N1B—C6B—H6B119.3
N1A—C11A—H11A109.5N1B—C11B—H11D109.5
N1A—C11A—H11B109.5N1B—C11B—H11E109.5
H11A—C11A—H11B109.5H11D—C11B—H11E109.5
N1A—C11A—H11C109.5N1B—C11B—H11F109.5
H11A—C11A—H11C109.5H11D—C11B—H11F109.5
H11B—C11A—H11C109.5H11E—C11B—H11F109.5
C6A—N1A—C2A—C3A1.1 (3)C6B—N1B—C2B—C3B0.6 (3)
C11A—N1A—C2A—C3A179.6 (2)C11B—N1B—C2B—C3B179.3 (2)
N1A—C2A—C3A—C4A0.4 (3)N1B—C2B—C3B—C4B1.3 (4)
C2A—C3A—C4A—C5A0.5 (3)C2B—C3B—C4B—C5B0.9 (3)
C2A—C3A—C4A—S41A179.83 (16)C2B—C3B—C4B—S41B179.77 (18)
C3A—C4A—C5A—C6A0.7 (3)C3B—C4B—C5B—C6B0.1 (3)
S41A—C4A—C5A—C6A179.92 (18)S41B—C4B—C5B—C6B179.19 (18)
C2A—N1A—C6A—C5A0.9 (3)C4B—C5B—C6B—N1B0.8 (4)
C11A—N1A—C6A—C5A179.4 (2)C2B—N1B—C6B—C5B0.5 (3)
C4A—C5A—C6A—N1A0.1 (4)C11B—N1B—C6B—C5B178.2 (2)

Experimental details

Crystal data
Chemical formulaC6H7NS
Mr125.19
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)7.544 (1), 9.085 (1), 9.302 (1)
α, β, γ (°)89.84 (1), 84.03 (1), 87.98 (1)
V3)633.7 (1)
Z4
Radiation typeCu Kα
µ (mm1)3.59
Crystal size (mm)0.32 × 0.28 × 0.26
Data collection
DiffractometerEnraf-Nonius CAD4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2861, 2654, 2012
Rint0.022
(sin θ/λ)max1)0.635
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.135, 1.04
No. of reflections2654
No. of parameters148
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.47, 0.37

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), SDP (B. A. Frenz & Associates Inc., 1985), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976).

Selected geometric parameters (Å, º) top
N1A—C6A1.351 (3)N1B—C2B1.351 (3)
N1A—C2A1.354 (3)N1B—C6B1.353 (3)
N1A—C11A1.468 (3)N1B—C11B1.470 (3)
C2A—C3A1.346 (3)C2B—C3B1.351 (3)
C3A—C4A1.415 (3)C3B—C4B1.419 (3)
C4A—C5A1.418 (3)C4B—C5B1.412 (3)
C4A—S41A1.697 (2)C4B—S41B1.6922 (19)
C5A—C6A1.352 (3)C5B—C6B1.350 (3)
C6A—N1A—C2A118.71 (19)C2B—N1B—C11B121.2 (2)
C6A—N1A—C11A121.21 (19)C6B—N1B—C11B120.0 (2)
C2A—N1A—C11A120.07 (19)N1B—C2B—C3B121.77 (19)
C3A—C2A—N1A121.57 (18)C2B—C3B—C4B121.76 (19)
C2A—C3A—C4A122.11 (18)C5B—C4B—C3B113.95 (18)
C3A—C4A—C5A114.18 (19)C5B—C4B—S41B122.90 (16)
C3A—C4A—S41A123.53 (16)C3B—C4B—S41B123.14 (15)
C5A—C4A—S41A122.29 (15)C6B—C5B—C4B122.29 (19)
C6A—C5A—C4A121.52 (19)C5B—C6B—N1B121.40 (18)
C2B—N1B—C6B118.80 (17)
 

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