Synthesis, EPR and Mössbauer spectral studies of new iron(III) complexes with 2-benzoylpyridine-N(4), N(4)-(butane-1,4-diyl) thiosemicarbazone (HBpypTsc): X-ray structure of [Fe(BpypTsc) 2]FeCl 4 · 2H 2O and the free ligand

Abstract

Three novel iron(III) complexes of 2-benzoylpyridine N(4), N(4)-(butyl-1,4-diyl) thiosemicarbazone (HBpypTsc), [Fe(BpypTsc) 2]ClO 4 ( 1), [Fe(BpypTsc) 2]NO 3 ( 2) and [Fe(BpypTsc) 2]FeCl 4 ( 3) were synthesized and physico-chemically characterized by means of partial elemental analyses, magnetic measurements (polycrystalline state), UV–Vis and IR spectroscopies. The spin Hamiltonian parameters, isomer shifts and quadrupolar splitting values of the complexes were assigned by variable temperature EPR and Mössbauer spectra. The presence of a spin-paired iron(III) cation with d xz 2d yz 2d xy 1 ground state is revealed by the simulated EPR spectral data. The structures of the free ligand HBpypTsc and one of the complexes [Fe(BpypTsc) 2]FeCl 4 ( 3) were solved by single crystal X-ray diffraction which authenticated a FeN 4S 2 octahedral coordination in the complex, as envisaged from the spectral data. All complexes except [Fe(BpypTsc) 2]FeCl 4 ( 3) were found to be low-spin S=1/2 ( 2T 2g), whereas 3 was found to have both low-spin ( 2T 2g) and high-spin ( 6A 1) centres.