Bis(1,3,4-thia­diazol-2-yl) di­sulfide

The title compound, C₄H₂N₄S₄, lies about a twofold rotation axis situated at the mid-point of the central S—S bond. Each of two thia­diazole rings is essentially planar, with an rms deviation for the unique thia­diazole ring plane of 0.0019 (7) Å. C—H⋯N hydrogen bonds link adjacent mol­ecules, forming zigzag chains along the c axis. In addition, these chains are connected by inter­molecular S⋯S inter­actions [S⋯S = 3.5153 (11) Å] , forming corrugated sheets, and further fabricate a three-dimensional supra­molecular structure by inter­molecular N⋯S contacts [S⋯N = 3.1941 (17) Å].

Related literature

For potential applications of thia­diazo­les, see: Coyanis et al. (2002); Wang & Cao (2005). For their use as ligands in transition-metal coordination chemistry, see: Huang et al. (2004); Zheng et al. (2005). For the structure of bis­(2-methyl-1,3,4-thia­diazol­yl)-5,5′-disulfide, see: Hipler et al. (2003).

Experimental

Crystal data

• C₄H₂N₄S₄

• M_r = 234.34

• Monoclinic, C 2/c

• a = 9.706 (2) Å

• b = 4.8980 (12) Å

• c = 18.008 (5) Å

• β = 100.074 (3)°

• V = 842.9 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 1.07 mm⁻¹

• T = 291 K

• 0.29 × 0.20 × 0.11 mm

Data collection

• Bruker SMART CCD area detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 1997) T_min = 0.746, T_max = 0.889

• 2915 measured reflections

• 783 independent reflections

• 727 reflections with I > 2σ(I)

• R_int = 0.017

Refinement

• R[F² > 2σ(F²)] = 0.021

• wR(F²) = 0.055

• S = 1.11

• 783 reflections

• 55 parameters

• H-atom parameters constrained

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.26 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯N2^i	0.93	2.52	3.249 (2)	136
Symmetry code: (i) -x+1, -y+2, -z+1.

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

Thiadiazoles have attracted increasing attention because of their potential applications in pharmaceutical, agricultural, industrial, coordination and polymer chemistry (Coyanis et al., 2002, Wang & Cao, 2005). Ligands involving thiadiazole group have also shown interesting coordination chemistry with transition metal ions (Huang et al., 2004; Zheng et al., 2005). Exploring the applications of thiadiazole derivatives as ligands for metal complexation, we report here the synthesis and structure of bis(1,3,4-thiadiazolyl)5,5'-disulfide (I), a new and potentially multi-functional ligand (Fig. 1).

The title compound,C₄H₂N₄S₄, lies about a twofold rotation axis situated at the mid-point of the central S–S bond. Each of the thiadiazole rings is essentially planar, with an rms deviation for the unique thiadiazole ring plane of 0.0019 (7)Å. The dihedral angle and centroid-centroid distance between the two thiadaizole rings are 86.64 (44)° and 5.25 (14) Å, respectively. The N1-C1 and N2-C2 bond lengths, 1.298 (2) Å and 1.290 (2) Å, respectively, indicate significant double bond character, which is very similar to the structure of bis(2-methyl-1,3,4-thiadiazolyl)-5,5'-disulfide (Hipler, et al., 2003).

In the crystal structure, molecules of (I) form 1-dimensional zigzag chains by way of weak intermolecular C-H···N hydrogen bonds along the c axis (Fig.3). In addition, these chains are linked by intermolecular S···S interactions [S2···S1 = 3.5153 (11) Å] to form corrugated sheets (Fig. 3). Further intermolecular N···S interactions (S2···N1 = 3.1941 (17) Å] generate a 3-dimensional supramolecular network structure (Fig. 4).

Related literature

For potential applications of thiadiazoles, see: Coyanis et al. (2002); Wang & Cao (2005). For their use as ligands in transition-metal coordination chemistry, see: Huang et al. (2004); Zheng et al. (2005). For the structure of bis(2-methyl-1,3,4-thiadiazolyl)-5,5'-disulfide, see: Hipler et al. (2003).

S2. Experimental

The title compound was prepared by adding hydrogen peroxide (30%, 10.4 mL) drop-wise to a solution of 2-mercapto-1,3,4-thiadiazole (0.2 mol) in ethanol (30 mL) and water (20 mL) at room temperature. The mixture was then refluxed for 6 h. The reaction mixture was taken up in hexane (100 mL), washed with water and brine, and dried with Na₂SO₄. The solvent was removed under reduced pressure, and the crude product was recrystallised from ethanol to give the title compound as colourless solid in 85% yield. Colorless block-like single crystals were obtained by slow evaporation from ethanol at room temperature.

S3. Refinement

The H atoms were positioned geometrically and treated as riding with d(C-H) = 0.93Å, U_iso=1.2U_eq (C)

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. View of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. The 1-dimensional zigzag chain formed by intermolecular C-H···N interactions, shown as dashed lines.
	Fig. 3. Corrugated sheets formed by intermolecular C-H···N and S···S interactions, shown as dashed lines.
	Fig. 4. The 3-dimensional network structure formed by intermolecular C–H···N, S···S and N···S interactions, shown as dashed lines.

Bis(1,3,4-thiadiazol-2-yl) disulfide

Crystal data

C4H2N4S4	F(000) = 472
Mr = 234.34	Dx = 1.847 Mg m^−3
Monoclinic, C2/c	Melting point: 384 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 9.706 (2) Å	Cell parameters from 1881 reflections
b = 4.8980 (12) Å	θ = 2.3–28.3°
c = 18.008 (5) Å	µ = 1.07 mm^−1
β = 100.074 (3)°	T = 291 K
V = 842.9 (4) Å^3	Block, colorless
Z = 4	0.29 × 0.20 × 0.11 mm

Data collection

Bruker SMART CCD area detector diffractometer	783 independent reflections
Radiation source: fine-focus sealed tube	727 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
ϕ and ω scans	θmax = 25.5°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 1997)	h = −11→11
Tmin = 0.746, Tmax = 0.889	k = −5→5
2915 measured reflections	l = −21→21

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.021	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.055	H-atom parameters constrained
S = 1.11	w = 1/[σ^2(Fo^2) + (0.0269P)^2 + 0.5364P] where P = (Fo^2 + 2Fc^2)/3
783 reflections	(Δ/σ)max = 0.001
55 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.26 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes)

are estimated using the full covariance matrix. The cell esds are taken

into account individually in the estimation of esds in distances, angles

and torsion angles; correlations between esds in cell parameters are only

used when they are defined by crystal symmetry. An approximate (isotropic)

treatment of cell esds is used for estimating esds 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 > 2sigma(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	0.58334 (4)	0.20034 (8)	0.72250 (2)	0.03599 (15)
S2	0.37175 (4)	0.60103 (10)	0.63157 (3)	0.04226 (16)
C1	0.53518 (15)	0.4548 (3)	0.65306 (8)	0.0291 (3)
C2	0.43894 (19)	0.7877 (4)	0.56554 (9)	0.0393 (4)
H2	0.3858	0.9153	0.5347	0.047*
N1	0.62594 (14)	0.5425 (3)	0.61357 (8)	0.0388 (3)
N2	0.56803 (16)	0.7391 (3)	0.56152 (8)	0.0414 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0434 (3)	0.0342 (3)	0.0334 (2)	0.00958 (17)	0.01497 (18)	0.00365 (16)
S2	0.0290 (2)	0.0495 (3)	0.0495 (3)	0.00302 (18)	0.01012 (19)	0.0138 (2)
C1	0.0310 (8)	0.0296 (8)	0.0274 (7)	0.0002 (6)	0.0072 (6)	−0.0023 (6)
C2	0.0433 (10)	0.0400 (10)	0.0333 (9)	−0.0019 (7)	0.0034 (7)	0.0067 (7)
N1	0.0358 (8)	0.0441 (8)	0.0390 (8)	0.0026 (6)	0.0137 (6)	0.0069 (6)
N2	0.0463 (9)	0.0443 (8)	0.0354 (7)	−0.0022 (7)	0.0118 (6)	0.0079 (6)

Geometric parameters (Å, º)

S1—C1	1.7695 (16)	C1—N1	1.298 (2)
S1—S1^i	2.0393 (9)	C2—N2	1.290 (2)
S2—C2	1.7164 (17)	C2—H2	0.9300
S2—C1	1.7217 (16)	N1—N2	1.392 (2)
C1—S1—S1^i	102.08 (5)	N2—C2—S2	115.54 (13)
C2—S2—C1	86.01 (8)	N2—C2—H2	122.2
N1—C1—S2	115.22 (12)	S2—C2—H2	122.2
N1—C1—S1	119.96 (12)	C1—N1—N2	111.40 (13)
S2—C1—S1	124.81 (9)	C2—N2—N1	111.82 (14)
C2—S2—C1—N1	−0.11 (13)	S2—C1—N1—N2	−0.16 (18)
C2—S2—C1—S1	−179.53 (11)	S1—C1—N1—N2	179.30 (11)
S1^i—S1—C1—N1	169.70 (12)	S2—C2—N2—N1	−0.5 (2)
S1^i—S1—C1—S2	−10.90 (11)	C1—N1—N2—C2	0.4 (2)
C1—S2—C2—N2	0.38 (15)

Symmetry code: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···N2^ii	0.93	2.52	3.249 (2)	136

Symmetry code: (ii) −x+1, −y+2, −z+1.