Synthesis, Spectroscopic and Thermal Investigations of O‐Phd and P‐Phd Bridged Binuclear Manganese (III) Schiff Base Complexes Derived from Pyrazolone Base Ligands

Abstract

Acyl pyrazolone and their derivatives are an important class of chelating compounds called heterocyclic β‐diketones. β‐diketones have played, and continue to play, a key role in coordination compounds that have found wide application in several fields, from new materials to catalysts, as precursors for CVD in the microelectronic industry and as potential antitumourals. Due to variety of application of this class of ligand, there are studies on metal complexes of many researchers, including ours. We herein report the structural variability of pyrazolone moiety and its chelating nature with manganese (III) ions, in mononuclear and binuclear complexes. The mononuclear complex [Mn(PMFP)(bipy)(OAc)]ClO4 and [Mn(PMFP‐Me) (bipy)(OAc)]ClO4 was prepped by reaction of Mn(OAc)3 · 2H2O with ligand PMFP or PMFP‐Me (where PMFP=5‐Hydroxy‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde; PMFP‐Me=5‐hydroxy‐3‐methyl‐1‐p‐tolyl‐1H‐pyrazole‐4‐carbaldehyde; bipy=2,2′bipyridyl). The corresponding binuclear complexes were prepared by bridging molecule, o‐phD or p‐phD (o‐phD= where o‐phenelene diamine or p‐phD=p‐phenelen diamine). Both the ligand PMFP and PMFP‐Me were characterized by elemental analysis and 1H‐NMR, GC‐MS, FT‐IR spectroscopic study. The resulting complexes have been characterized by elemental analysis, magnetic susceptibility and conductometry measurements and spectroscopic methods FT‐IR, electronic spectra and mass spectrometry. All the complexes were electrolytic in nature and consist of 1∶2 electrolytes in solution. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese (III) ion. TGA and DSC determined thermal stability, heat capacity and activation energy of thermal degradation for these complexes.