Dichlorido{(2E)-2-[phenyl(pyridin-2-yl)methylidene]hydrazinecarbothioamide}cadmium(II) methanol monosolvate

In the title compound, [CdCl2(C13H12N4S)]·CH3OH, the coordination geometry of the CdII ion is slightly distorted square-pyramidal, as indicated by the τ index of 0.36 (8). The S atom, two N atoms from the pyridyl-azomethine moiety and one of the Cl atoms comprise the basal plane, while the other Cl atom occupies the apical position. The hydrazinecarbothioamide moiety adopts an E conformation with respect to the azomethine bond. The solvate molecule in the crystal lattice plays a major role in interconnecting adjacent molecules by means of O—H⋯Cl and N—H⋯O hydrogen-bonding interactions. A supramolecular three-dimensional architecture is sustained in terms of further N—H⋯Cl and C—H⋯Cl hydrogen-bonding interactions.

In the title compound, [CdCl 2 (C 13 H 12 N 4 S)]ÁCH 3 OH, the coordination geometry of the Cd II ion is slightly distorted square-pyramidal, as indicated by the index of 0.36 (8). The S atom, two N atoms from the pyridyl-azomethine moiety and one of the Cl atoms comprise the basal plane, while the other Cl atom occupies the apical position. The hydrazinecarbothioamide moiety adopts an E conformation with respect to the azomethine bond. The solvate molecule in the crystal lattice plays a major role in interconnecting adjacent molecules by means of O-HÁ Á ÁCl and N-HÁ Á ÁO hydrogenbonding interactions. A supramolecular three-dimensional architecture is sustained in terms of further N-HÁ Á ÁCl and C-HÁ Á ÁCl hydrogen-bonding interactions.

S1. Comment
The importance of hydrazinecarbothioamide is increasing in various fields due to its wide range of medicinal applications (Joseph et al., 2004) and structural diversity due to their variable coordinative abilities (Sreekanth et al., 2004) arising from thioamido-thioiminol tautomerism. Moreover it also found to serve as a corrosion inhibitor on mild steel in HCl (Kumar et al., 2011). Recently a new heterocyclic hydrazinecarbothioamide has been developed as colorimetric and turn on fluorescent sensors for fluoride anion (Kumar et al., 2013).
The title complex [C 13 H 12 CdCl 2 N 4 S]·(CH 4 O) adopts an E configuration with respect to C6═N2 bond and the tridentate ligand has its coordinating entities disposed in a cis fashion to each other (Fig. 1). The Cd atom in the complex is N,N ′ ,S chelated by the thioamido form of the hydrazinecarbothioamide ligand. The C6═N2 [1.278 (3) Å] and C13=S1 [1.690 (2) Å] bond distances, very close to the formal C═N and C═S bond lengths respectively confirm the azomethine bond formation and the coordination via thioamido form. The coordination geometry around Cd(II) ion is almost square pyramidal (Addison et al., 1984) with a slight distortion (τ = 0.36 (8)). The S1 atom of the hydrazinecarbothioamide moiety, the imino N2 atom, pyridine N1 atom and the Cl1 atom comprise the basal plane while the apical position is occupied by the Cl2 atom (Kunnath et al., 2012). However, the deviation from the ideal square pyramidal geometry is observed by the displacement of Cd atom from the basal plane and the trans angle of the basal atoms (Table 1).
There are four classical O-H···Cl, N-H···O and N-H···Cl and one non-classical C-H···Cl intermolecular hydrogen bonding interactions (Table 1

S2. Experimental
The potentialy tridentate ligand (2E)-2-[phenyl(pyridin-2-yl)methylidene]hydrazinecarbothioamide was synthesized in situ by mixing equimolar methanolic solutions of phenyl(pyridin-2-yl)methanone (0.0916 g, 0.5 mmol), hydrazinecarbothioamide (0.0455 g, 0.5 mmol) and 5 drops of glacial acetic acid for 2 h. The title complex was prepared by adapting a reported procedure (Philip et al., 2006) by refluxing the above ligand solution and CdCl 2 ·2.5H 2 O (0.1141 g, 0.5 mmol) for 3 h. The resulting solution was cooled at room temperature. Upon slow evaporation, yellow coloured product formed were collected, washed with few drops of methanol and dried over P 4 O 10 in vacuo. Yellow blocked shaped single crystals of the title compound suitable for X-ray analysis were obtained by recrystallization from methanol. The compound was obtained in 56%, yield (0.1320 g).

Figure 1
ORTEP view of the compound, drawn with 50% probability displacement ellipsoids for the non-H atoms.     A view of the unit cell along a axis.