Formation of polynuclear iron(III) complexes of N-(2-pyridylmethyl)iminodipropanol depending on pseudohalide ions: synthesis, crystal structure, and magnetic properties

Abstract

Five polynuclear iron(III) complexes, [(pmidp)Fe(NCSe)]2 (1), [(pmidp)Fe(NCBH3)]2 (2), [(Hpmidp/pmidp)Fe3(CH3O)2(NCS)4]∙H2O (3), [(pmidp)2Fe6(CH3O)4(N3)4(CH3COO)2O2] (4), and [(pmidp)2Fe6(CH3O)4(NCO)4(CH3COO)2O2]∙2MeOH (5) were isolated through the reactions of N-(2-pyridylmethyl)iminodipropanol (H2pmidp) and iron(III) ions with different pseudohalide ions. The complexes were studied via X-ray crystal diffraction, Mössbauer spectra, and magnetochemistry. The molecular structures of 1 and 2 were formed as the {Fe2(µ2-Opropoxo)2}2+ cores with pmidp2− and NCSe−/NCBH3−. The structure of 3 was formed as a {Fe3(µ2-OCH3)2(µ2-Opropoxo)4}5+ core with Hpmidp−/pmidp2− and NCS−. The structures of 4 and 5 were formed as {Fe6(µ4-O)2(µ2-OCH3)2(η2-OAc)2(µ2-Opropoxo)4} cores with pmidp2− and NCO−/N3−. Structural analyses revealed that the formation of various multinuclear iron(III) moieties depends on the auxiliary ligands. The oxidation states of all the complexes were confirmed as + 3 using the bond valence sum (BVS) calculations and Mössbauer spectral data. The susceptibility data for 1–5 fitted using each spin coupling (J) model indicated that 1–3 showed antiferromagnetic exchange interactions, and 4 and 5 showed the ferromagnetic and antiferromagnetic couplings, simultaneously.