1,3,4-Thia­diazo­lium-2-thiol­ate

Mol­ecules of the title compound, C₂H₂N₂S₂, exist in the crystal structure in the zwitterionic form with the thiol group deprotonated. Hydrogen bonds between the protonated N atoms and the thiol­ate S atoms link the mol­ecules in a zigzag packing arrangement parallel to the ac plane.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](N-C) = 0.002 Å
• R factor = 0.021
• wR factor = 0.056
• Data-to-parameter ratio = 19.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT322_ALERT_2_C Check Hybridisation of  S1     in Main Residue .          ?

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Thiadiazoles have attracted increasing attention because of their potential applications in pharmaceutial, agricultural, industrial, coordination and polymer chemistry (Coyanis et al., 2002; Wang & Cao, 2005).

Molecules of the title compound, (I), exist in the crystal structure in a zwitterionic form, with the thiadiazole atom N1 protonated and the thiol substituent deprotonated (Fig. 1). The thiodiazole ring is planar, with a maximum deviation from the ring plane of 0.0082 (7) Å for atom N1. The thiolate atom S2 lies 0.018 (6) Å from that plane.

N1—H1···S2 hydrogen bonds link adjacent molecules in a zigzag network parallel to the ac plane (Figs. 2 and 3).

S2. Experimental

Dilute hydrochloric acid (Volume?) was added to a solution of 2-mercapto-1,3,4-thiadiazole (1 g) in water (20 ml). Subsequent crystallization over 2 weeks gave colourless needle-like crystals of (I) suitable for X-ray diffraction analysis.

S3. Refinement

H atoms were treated as riding, with C—H = 0.93 Å and N—H = 0.86 Å, and with U_iso(H) = 1.2U_eq(C,N).

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2; data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2004); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A view of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. The one-dimensional chain structure of (I) formed by N—H···S hydrogen bonds (dashed lines) along the c axis.
	Fig. 3. The zigzag packing arrangement of (I) in the ac plane. Hydrogen bonds are drawn as dashed lines.

1,3,4-Thiadiazolium-2-thiolate

Crystal data

C2H2N2S2	F(000) = 480
Mr = 118.18	Dx = 1.688 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 4625 reflections
a = 8.623 (2) Å	θ = 3.1–28.3°
b = 8.249 (2) Å	µ = 0.97 mm^−1
c = 13.075 (3) Å	T = 296 K
V = 930.0 (4) Å^3	Needle, colourless
Z = 8	0.32 × 0.13 × 0.13 mm

Data collection

Bruker APEX-2 CCD area-detector diffractometer	1066 independent reflections
Radiation source: fine-focus sealed tube	1000 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
ϕ and ω scans	θmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.747, Tmax = 0.884	k = −10→10
7289 measured reflections	l = −16→16

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.021	H-atom parameters constrained
wR(F^2) = 0.056	w = 1/[σ^2(Fo^2) + (0.0291P)^2 + 0.2499P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
1066 reflections	Δρmax = 0.26 e Å^−3
56 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.069 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
S1	0.09586 (4)	0.15440 (4)	0.60840 (2)	0.03849 (13)
S2	0.21697 (4)	−0.03176 (4)	0.79383 (2)	0.04018 (14)
N1	0.37514 (12)	0.09299 (14)	0.63640 (8)	0.0365 (2)
H1	0.4600	0.0562	0.6620	0.044*
N2	0.37633 (13)	0.17856 (15)	0.54651 (8)	0.0431 (3)
C1	0.23979 (14)	0.06778 (14)	0.68338 (9)	0.0307 (2)
C2	0.23609 (15)	0.21803 (17)	0.52344 (10)	0.0408 (3)
H2	0.2121	0.2769	0.4649	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.03080 (19)	0.0484 (2)	0.0362 (2)	0.00549 (12)	−0.00182 (11)	0.00581 (13)
S2	0.0376 (2)	0.0481 (2)	0.0349 (2)	0.00590 (13)	0.00539 (11)	0.01104 (13)
N1	0.0294 (5)	0.0484 (6)	0.0317 (5)	0.0021 (4)	0.0011 (4)	0.0060 (4)
N2	0.0400 (6)	0.0561 (7)	0.0332 (6)	−0.0003 (5)	0.0047 (4)	0.0093 (5)
C1	0.0303 (5)	0.0329 (5)	0.0289 (5)	0.0023 (4)	−0.0001 (4)	−0.0018 (4)
C2	0.0449 (7)	0.0486 (7)	0.0290 (6)	0.0035 (6)	0.0005 (5)	0.0057 (5)

Geometric parameters (Å, º)

S1—C2	1.7238 (14)	N1—N2	1.3709 (15)
S1—C1	1.7356 (12)	N1—H1	0.8600
S2—C1	1.6727 (13)	N2—C2	1.2882 (17)
N1—C1	1.3353 (16)	C2—H2	0.9300
C2—S1—C1	89.30 (6)	N1—C1—S1	107.52 (9)
C1—N1—N2	118.76 (10)	S2—C1—S1	127.28 (7)
C1—N1—H1	120.6	N2—C2—S1	115.51 (10)
N2—N1—H1	120.6	N2—C2—H2	122.2
C2—N2—N1	108.89 (10)	S1—C2—H2	122.2
N1—C1—S2	125.20 (9)
C1—N1—N2—C2	−0.94 (17)	C2—S1—C1—S2	179.59 (9)
N2—N1—C1—S2	−179.26 (9)	N1—N2—C2—S1	−0.02 (16)
N2—N1—C1—S1	1.39 (14)	C1—S1—C2—N2	0.66 (12)
C2—S1—C1—N1	−1.08 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···S2^i	0.86	2.40	3.2527 (13)	170

Symmetry code: (i) x+1/2, y, −z+3/2.