NOVEL DINUCLEAR PALLADIUM(II) COMPLEXES WITH THE CHELATING LIGAND BIS(1-METHYLIMIDAZOL-2-YL) KETONE (BMIK) AND PYRIDINE-2-THIOLATE, PYRIMIDINE-2-THIOLATE, AND 1-METHYLIMIDAZOLE-2-THIOLATE AS BRIDGING SECONDARY LIGANDS

Three novel dinuclear palladium(II) complexes with the chelating ligand bis(1-methylimidazol-2-yl) ketone (bmik) as well as pyridine-2-thiolate (pyt), pyrimidine-2-thiolate (pymt), and 1-methylimidazole-2-thiolate (meimt) as bridging secondary ligands were prepared by reactions of diaqua[bis(1-methylimidazol-2-yl) ketone]palladium(II) nitrate with ligands in aqueous solution. The thiolates bridge the two metal atoms in the mu-N,S mode. The structures of the following compounds were analyzed by single crystal X-ray diffraction: Bis(mu-pyridine-2-thiolato-N,S)-bis'[bis(1-methyl-imidazol-2-yl) ketone]palladium(II)'nitrate [Pd-2(bmik)(2)-(pyt)(2)](NO3)(2).5H(2)O (1), bis (mu-pyrimidine-2-thiolato-N-1,S)-bis'[bis(1-methylimidazol-2-yl) ketone]palladium(II)' nitrate [Pd-2(bmik)(2)(pymt)(2)](NO3)(2).5H(2)O (2), and bis(mu-1-methylimidazole-2-thiolato-N-3,S)-bis'[bis(1-methylimidazol-2-yl) ketone]palladium(II)' nitrate [Pd-2(bmik)(2)(meimt)(2)](NO3)(2).4.5 H2O (3). In the cases of 1 and 3 the bridging thiolate ligands show head-to-head orientation. For complex 2 a head-to-tail orientation of the pyrimidine-2-thiolates was found. The metal-metal distances vary from 2.963 Angstrom in complex 3 and 2.915 Angstrom in 1 to the shortest of 2.886 Angstrom in 2. In addition to the x-ray crystallography the three compounds were characterized by H-1-NMR and IR spectroscopy.