Synthesis and spectroscopic studies on iron(III) complexes of 1-benzotriazol-1-yl-1-[(p-X-phenyl)hydrazono]propan-2-one

A new series of iron(III) complexes are synthesized from the reaction of the polyfunctional ligands 1-benzotriazol-1-yl-1-[p-X-phenyl]hydrazono]propan-2-one (X = H, Cl, NO2, CH3 or OCH3 corresponding to HL1,HL2, HL3, HL4 or HL5, respectively, with iron(III) chloride in the presence of LiOH by the conventional and microwave induced energy methods. The conventional method led to the formation of [FeL3]·nH2O but the microwave induced energy gave [FeLCl2], n = 1–3 and L is the anion of HL1–HL5. The complexes are characterized by the elemental analysis, molar conductivity, magnetic and spectral (FT-IR, UV–vis and ESR) studies. The magnetic and spectral studies showed that [FeLCl2] are polymeric octahedral, [Fe(L1)3]·H2O is a low spin octahedral and (dxz,dyz)4 (dxy)1 ground state, [FeL3]·nH2O, L = anion of HL4 or HL5 and are octahedral with intermediate spin (S=32) with ground state (dxy)2(dxz,dyz)3 electronic configuration while for the anions of HL2 and HL3, they have (t2g)3(eg)5 admixed with (dxy)2(dxz,dyz)3 configurations. From the ESR data, the contribution of the high spin (S=52) and low spin (S=32) to the quantum mechanical spin intermediate (QMS), and the crystal field parameters Δ and V are calculated and related to the electronic and steric effects of the ligands. The electronic spectral data confirm that obtained from the ESR, and the different ligand field parameters as well as the π → t2g, t2g → eg, eg → π*, π → π* transitions are estimated and compared with that experimentally obtained.