Synthesis and spectroscopic identification of new iron(III) complexes with 5-methyl-3-formylpyrazole-3-piperidinylthiosemicarbazone (HMP z3Pi): X-ray structure of [Fe(MP z3Pi) 2]ClO 4·2H 2O

Abstract

New iron(III) complexes of 5-methyl-3-formylpyrazole-3-piperidinylthiosemicarbazone (HMP z 3Pi), [Fe(MP z 3Pi) 2]X·2H 2O (X=Cl, ClO 4 and NO 3) have been synthesised and physico-chemically characterised by magnetic data (polycrystalline state), electronic, IR and EPR spectral studies. Each of the reported species is a cationic complex (1:1 electrolyte) containing two moles of monodeprotonated title ligand and an anionic counterpart. IR spectra (4000–200 cm −1) indicate coordination to the central iron(III) ion via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atoms of the primary ligand molecule. EPR data (RT and LNT) show the presence of a low spin iron(III) cation with d 2 xz d 2 yz d 1 xy configuration. X-ray crystallographic data of [Fe(MP z 3Pi) 2]ClO 4·2H 2O ( P 1 ̄ , triclinic) have authenticated a FeN 4S 2 octahedral coordination as envisaged from spectral data. In the complex species, the two azomethine nitrogen atoms are trans to each other, while the pyrazolyl ring nitrogens and the thiolato sulfurs are in cis positions.