PALLADIUM(II) COMPLEXES OF TRIDENTATE LIGANDS - THE CRYSTAL-STRUCTURE OF CHLORO[2,6-DI(2-IMIDAZOLIN-2-YL)PYRIDINE]PALLADIUM(II) CHLORIDE

Mono(ligand) palladium(II) complexes of 2,6-di-(thiazol-2-yl)pyridine (1a), 2,6-di(4-methylthiazol-2-yl) pyridine (1b), 2,6-di(thiazol-4-yl)pyridine (2a), 2,6-di(imidazolin-2-yl)pyridine (3) and 2,6-di(benzimidazol-2-yl)pyridine (4a) of the general formula [PdLCl]Cl have been prepared. Stoichiometries have been confirmed by C, H, N and Pd analyses; the presence of solvate molecules has been confirmed by thermogravimetry. The crystal structure of [PdLCl]Cl.H2O, L = (3), has been determined by single-crystal X-ray diffractometry. The compound crystallizes in an orthorhombic space group, Pna 2(1), a 7.427(2), b 21.932(3), c 8.935(1) angstrom. The geometry of the complex cation is approximately square planar. The imidazolinyl rings closely approach planarity which is imposed by the delocalization of pi-density in the NCN moiety. A hydrogen-bonding scheme involving the imino hydrogens of the ligand, chloride ions and the water molecule is present. The structure was refined by least-squares methods to a residual of 0.018 for 1273 reflections.