MMINE(PYRAZINE-2,3-DICARBOXYLATO-N,O)PALLADIUM(II) - SYNTHESIS, CRYSTAL-STRUCTURE, SPECTROSCOPIC AND THERMAL-PROPERTIES

The synthesis, crystal structure and spectroscopic (IR, XPS) character ization of a new Pd complex with 2,3-pyrazinedicarboxylic acid (2,3-H( 2)pzdc), Pd(2,3-pzdc)(NH3)(2) (1), are reported. This compound crystal lizes in the monoclinic space group P2(1)/c with four molecules in the unit cell. Using 2697 independent reflections up to 2 theta=60 degree s, the structure was refined to R = 0.044. The lattice is formed of is olated zwitterionic moieties in which the square-planar coordination o f palladium is ensured by three nitrogen atoms and one oxygen from a c arboxylate group attached to the pyrazine ring. Both the structural an d the infrared data confirm the absence of a polymeric network. Therma l degradation under nitrogen produces a mixture of palladium metal and PdO at 773 K. The XPS data of 1 are discussed together with those of a related compound with 3,5-pyrazoledicarboxylic acid (H(3)Dcp), (NBu4 )(2)[Pd-2(Dcp)(2)] (2) and suggest the presence of a delocalized posit ive charge in the pyrazine ring.