Crystal structure of 3-carbamothioylpyridinium thiocyanate

In the cation of the title salt, C6H7N2S+·SCN−, the C=S bond is oriented trans with respect to the C—C=N fragment in the pyridine ring. The planes of the aromatic ring and the thioamide fragment of the cation make a dihedral angle of 38.31 (4)°. In the crystal, the components are linked by N—H⋯S and N—H⋯N, hydrogen bonds, forming a two-dimensional network parallel to (10-1).

In the title compound, (I), the asymmetric unit contains one 3-3-carbamothioylpyridinium and one thiocyanate ions. The molecular geometry and the atom-numbering scheme are shown in Fig 1. In the cation moiety, the C=S bond is oriented trans with respect to the C-C-N fragment in the pyridine ring. The aromatic ring and the thioamide fragment of the thionicotinamide molecule make a dihedral angle of 38.31 (4)° similar to that found in 3-carbamothioylpyridinium iodide (trans) (30.02 (3)°) (Sharif et al., 2009) and 3-thioamido-pyridine (cis) (33.76 (7)°) (Form et al. 1973). The crystal packing is stabilized by weak N-H···N and N-H···S hydrogen bonds forming a two-dimensional network (Fig. 2).

S2. Experimental
3-Thionicotinamide (690 mg, 0.5 mmol) was added dropwise to a solution of KSCN (48.6 mg, 0.5 mmol) in water/ethanol (10 ml/10 ml). The mixture was then refluxed with stirring for 3 h and the resulting solution was left to stand at room temperature. After several days, single crystals suitable for X-ray diffraction were obtained.

S3. Refinement
Approximate positions for all H atoms were first obtained from the difference electron density map. However, the H atoms were situated into idealized positions and the H-atoms have been refined within the riding atom approximation.
The applied constraints were as follow: C-H = 0.93 Å and N-H = 0.86 Å with U iso = 1.2U eq (C or N).

Figure 1
The molecular structure of, (I), with displacement ellipsoids drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii.

Figure 2
Packing diagram of (I) viewed along the b axis showing hydrogen bond as dashed lines [N-H···S in red and N-H···N in black]

3-Carbamothioylpyridinium thiocyanate
Crystal data 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.