5,5′-[Methylenebis(sulfanediyl)]bis(1,3,4-thiadiazol-2-amine)

In the crystal structure of the title compound, C5H6N6S4, the molecules are linked by strong N—H⋯N hydrogen bonds into a two-dimensional network and an intramolecular C—H⋯S interaction also occurs.

In the crystal structure of the title compound, C 5 H 6 N 6 S 4 , the molecules are linked by strong N-HÁ Á ÁN hydrogen bonds into a two-dimensional network and an intramolecular C-HÁ Á ÁS interaction also occurs.

Related literature
For the multiple coordination environment of this ligand, see: Ma et al. (2007).

S2. Experimental
5-amino-1,3,4-thiadiazole-2-thiol(2 mmol), and sodium ethanolate were dissolved in ethanol, and the mixture was stirred for 4 h at 323 K. After cooling at room temperature, the solution was filtered. The solvent was removed from the filtrate under vacuum, and the solid residue was recrystallized from diethylether; colorless crystals suitable for X-Ray diffraction study were obtained. Yield, 81%. m.p. 368 K. Analysis, calculated for C 5 H 6 N 6 S 4 : C 21.57, H 2.17, N 30.19; found: C 21.36, H 2.43, N 30.32. The elemental analyses were performed with a Perkine Elemer PE2400II instrument.

S3. Refinement
The amido H atoms were placed in idealized positions and constrained to ride on their parent atoms, with amido N-H = 0.86 Å. The U iso (H) values were set at 1.2U eq (N) for the amido H atoms. The methylene H atoms could be located in difference Fourier maps. It was refined with distance restraints of C-H = 0.97 Å and U iso (H)= 1.2U eq (C).  The structure of the title complex, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
The H atoms are omitted for clarity.  The crystal packing of (I), viewed along the a axis. Dashed lines show intermolecular hydrogen bonds. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.47 e Å −3 Δρ min = −0.65 e Å −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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 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 (Å 2 )
x y z U iso */U eq N1 0.7436 (