Structure and property of unsymmetrical binuclear [(3,5-dimethylpyrazole)2Pd2(μ-3,5-dimethylpyrazolate)2(2,6-dipicolinate)] and mononuclear [Na2(H2O)4Pd(2,6-dipicolinate)2] complexes

Article abstract of DOI:10.1016/j.poly.2006.05.030

This work describes the synthesis and characterization of two Pd(II) complexes [(3,5-Hdmpz)₂Pd₂(μ-3,5-dmpz)₂(2,6-dipic)] (1) and [Na₂(H₂O)₄Pd(2,6-dipic)₂] (2) (3,5-Hdmpz = 3,5-dimethylpyrazole and 2,6-dipic = 2,6-pyridinedicarboxylate). The X-ray molecular structure determination shows that 1 is a binuclear complex bridged by two 3,5-dmpz units and is completely unsymmetric since one palladium atom contains two protonated 3,5-Hdmpz ligands and the other one contains the 2,6-dipic^2- unit that coordinates in a bidentate fashion. The central six-member Pd₂N₄ core shows a boat-like conformation where the palladium atoms are positioned at the vertices of the boat. The molecules are assembled in an extended zigzag one-dimensional network formed through 3,5-Hdmpz-carboxylate (2,6-dipic^2-) hydrogen bonds. The packing of complex 2 is constructed of cationic Na⁺-H₂O and anionic Pd-2,6-dipic^2- units joined together to form an extended two dimensional network. Alternate short and long Na-Na distances are observed in the cationic layer. A detailed quantum-chemical calculation on the Na-chains in 2 has been made. Complex 1 shows a luminescence property and antimicrobial activity against Bacillus subtilis, Escherichia coli and Aspergillus niger where the MIC has been found to be 100 μg/mL for all three species.