Synthesis, spectral, crystallography and thermal investigations of novel Schiff base complexes of manganese (III) derived from heterocyclic β-diketone with aromatic and aliphatic diamine

The Schiff base tetradentate ligands N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H2L1), N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H2L2), N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H2L3) and N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H2L4) were prepared from the reaction between 5-oxo-3-methyl-1-p-tolyl-1H-pyrazole-4-carbaldehyde or 4-(4-formyl-5-oxo-3-methyl-pyrazol-1-yl)-benzenesulfonic acid and o-phenylenediamine or ethylenediamine. And these are characterized by elemental analysis, FT-IR, 1H NMR and GC–MS. The corresponding Schiff base complexes of Mn(III) were prepared by condensation of [Mn3(μ3-O)(OAc)6(H2O)3]·3H2O with ligands H2L1, H2L2, H2L3 and H2L4. All these complexes have been characterized by elemental analysis, magnetic susceptibility, X-ray crystallography, conductometry measurement, FT-IR, electronic spectra and mass (FAB) spectrometry. Thermal behaviour of the complexes has been studied by TGA, DTA and DSC. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry of manganese (III) complexes, while non-electrolytic behaviour complexes indicate the absence of counter ion.