Spectroscopic Elucidation, Conductivity and Activation Thermodynamic Parameters Studies on Pt(IV), Au(III) and Pd(II) 1,5-Dimethyl-2-phenyl-4-[(thiophen-2-ylmethylene)-amino]-1,2-dihydro-pyrazol-3-one Schiff Base Complexes

Noble metal complexes of Schiff bases derived from 2-thiophenecarboxaldehyde and 4-aminoantipyrine (4APT) are discussed and characterized based on elemental analyses, IR, Raman, H-1-NMR, molar conductance, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy and thermal analysis (TGA). The complexes are found to have the formulas [Pt(4APT)Cl]Cl-3, [Pd(4APT)(Cl)(2)] and [Au(4APT)(Cl)(2)]Cl. The molar conductance data reveal that all the metal chelates of the 4APT ligand are non-to-electrolytes with difference degree of ionizable chloride ions. IR spectra show that 4APT is coordinated to the metal ions in a tridentate manner, with SNO donor sites of azomethine-N and thiophene-S in case of platinum(IV) complex, whereas the palladium(II) and gold(III) complexes are coordinated to the 4APT in a bidentate manner with SN donor sites of azomethine-N and thiophene-S. From the Raman spectra, it is found that the fluorescence natures of these complexes are displayed upon the broadening and scattering spectra. The thermal features of these chelates shows that the Pt(IV) hydrated complex lose water molecules of hydration in the first step and is immediately followed by decomposition of the anions and ligand moieties in the subsequent steps. The activation thermodynamic parameters of E*, Delta H*, Delta S*, and Delta G*, are calculated from the DrTG curves using the Coats-Redfern isothermal method. The synthesized ligand was also checked using mass spectroscopy and the fragmentation patterns are assigned.