Crystal Structure of [Pd(Imt) 4 ]Cl 2 and DFT Studies of [Pd(Imt) 4 ]Cl 2 and [Pd(Imt) 2 (CN) 2 ] (Imt = Imidazolidine-2-Thione)

The crystal structure of a palladium(II) complex of imidazolidine-2-thione (Imt), [Pd(Imt)4]Cl2 (I) was determined by X-ray crystallography (CIF file CCDC no. 1946290). The structure of complex I is ionic consisting of [Pd(Imt)4]2+ cation and two chloride counter ions. The palladium atom in the complex ion assumes a distorted square planar geometry. The complex cation and non-coordinated chloride ions are connected to each other through electrostatic and hydrogen bonding interactions. To compare the stability of I with its corresponding non-ionic species [Pd(Imt)2Cl2] . 2Imt (Ia), DFT calculations were performed in the gas phase as well as in the DMSO solvent. The IR spectra of the ligand Imt and complex I were reliably interpreted theoretically. The structures of two related cyanide complexes; [Pd(Imt)2(CN)2]2 (II) and [Pd(Imt)4][Pd(CN)4] (IIa) were also predicted by DFT calculations in terms of geometries and stability. The DFT results reveal that in the gas phase, the structure I is less stable in comparison to the calculated structure Ia by 11.26 kcal/mol (ΔG) but reverse is true when the DMSO solvent is included in the quantum chemical calculations. For the cyanide analogues, the ionic dinuclear form IIa is more stable than the dimer II of the mononuclear complex [Pd(Imt)2(CN)2] in gas phase by 13.37 kcal/mol but is less stable in calculations with DMSO by 6.86 kcal/mol.