Pyrazolyl Pd(II) complexes containing triphenylphosphine: Synthesis and antimycobacterial activity

Abstract Complexes of the type trans -[PdCl 2 (HL)(PPh 3 )], where HL = pyrazole ( 1 ); 3,5-dimethylpyrazole ( 2 ); 4-nitropyrazole ( 3 ); 4-iodopyrazole ( 4 ) and PPh 3  = triphenylphosphine, were synthesized and characterized by elemental analyses, infrared and 1 H NMR spectroscopies. Single-crystal X-ray diffraction determination on 3 ·0.9 CHCl 3 and 4 showed that the coordination geometry around Pd(II) is nearly square-planar, with the chloro ligands in a trans configuration. In vitro antimycobacterial evaluation demonstrated that compound 4 displayed a minimum inhibitory concentration (MIC) of 7.61 ± 2.18 μM, being superior to the values observed for some commonly used antituberculosis drugs and other metal-based complexes.