Bis{benzyl 3-[(1H-indol-3-yl)methylidene]dithiocarbazato-κ2 N 3,S}palladium(II) pyridine disolvate

The PdII ion in the title compound, [Pd(C17H14N3S2)2]·2C5H5N, is located on an inversion center and is four-coordinated by two of the deprotonated N,S-bidentate Schiff base ligands in a square-planar geometry. The dihedral angle between the aromatic ring planes within the ligand is 71.12 (9)°. The indole NH groups are bonded to the pyridine solvent molecules via an N—H⋯N interaction. The crystal structure is consolidated by intermolecular C—H⋯S interactions.

The Pd II ion in the title compound, [Pd(C 17 H 14 N 3 S 2 ) 2 ]Á-2C 5 H 5 N, is located on an inversion center and is fourcoordinated by two of the deprotonated N,S-bidentate Schiff base ligands in a square-planar geometry. The dihedral angle between the aromatic ring planes within the ligand is 71.12 (9) . The indole NH groups are bonded to the pyridine solvent molecules via an N-HÁ Á ÁN interaction. The crystal structure is consolidated by intermolecular C-HÁ Á ÁS interactions.

Related literature
For the analogous DMF disolvate Pd II complex, see: Khaledi & Mohd Ali (2011). For a discussion of the coordination chemistry of indole-based S-benzyldithiocarbazones, see: Khaledi et al. (2011).

Experimental
Crystal data [Pd(C 17 Table 1 Hydrogen-bond geometry (Å , ). The crystal of the title compound was obtained from a pyridine solution of the Pd II complex of indole-3-carbaldehyde S-benzyldithiocarbazone. Upon deprotonation, the Schiff base chelates the Pd II ion in an N,S-bidentate bonding mode to form a five-membered ring with the metal center. The Pd II ion, located on an inversion center, is four-coordinated by two of the Schiff base ligands in a square-planar geometry. The pyridine solvent molecules remain uncoordinated to the metal ion and are hydrogen bonded to indole NH groups. This is similar to what was observed in the structure of the analogous DMF solvate Pd II complex (Khaledi & Mohd Ali, 2011). In contrast, the cadmium(II) complex of the Schiff base ligand in a pyridine solution gave an octahedral complex wherein two trans-pyridine molecules are coordinated to the metal center (Khaledi et al., 2011). In the present structure, the aromatic ring planes within the ligand make a dihedral angle of 71.12 (9)°.
The pyridine solvent ring is nearly coplanar with the indole ring, the dihedral angle between them being 11.39 (19)°. The structure is further consolidated by intramolecular interactions of the types C-H···S and C-H···N (Table 1).

Experimental
The Schiff base ligand was prepared as reported previously (Khaledi et al., 2011). A solution of palladium(II) acetate (0.224 g, 1 mmol) in ethanol (30 ml) was added to an ethanolic solution (30 ml) of the ligand (0.65 g, 2 mmol) containing a few drops of triethylamine. The mixture was refluxed for an hour, then cooled to room temperature. The resulting brown solid was filtered, washed with cold ethanol and dried over siliga-gel. The crystals of the title compound were obtained by slow evaporation of a solution of the solid in pyridine.

Refinement
The C-bound H atoms were placed at calculated positions (C-H 0.95-0.99 Å) and were treated as riding on their parent C atoms. The N-bound H atom was located in a difference Fourier map, and was refined with a distance restraint of N-H 0.88±0.02. For all H atoms, U iso (H) was set to 1.2 U eq (carrier atom). Fig. 1. Thermal ellipsoid plot of the title compound at the 50% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius. The unlabeled atoms are related to the labeled atoms by symmetry operation: -x, -y, -z.

Figures
Crystal data [Pd(C 17