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, NO(2, CH(3) or OCH(3) corresponding to HL(1),HL(2), HL(3), HL(4) or HL(5), 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 [FeL(3)].nH(2)O but the microwave induced energy gave [FeLCl(2)], n=1-3 and L is the anion of HL(1)-HL(5). 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 [FeLCl(2)] are polymeric octahedral, [Fe(L(1))(3)].H(2)O is a low spin octahedral and (d(xz),d(yz))(4) (d(xy))(1) ground state, [FeL(3)].nH(2)O, L=anion of HL(4) or HL(5) and are octahedral with intermediate spin S=32 with ground state (d(xy))(2)(d(xz),d(yz))(3) electronic configuration while for the anions of HL(2) and HL(3), they have (t(2g))(3)(e(g))(5) admixed with (d(xy))(2)(d(xz),d(yz))(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 Delta 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 pi-->t(2g), t(2g)-->e(g), e(g)-->pi*, pi-->pi* transitions are estimated and compared with that experimentally obtained.