Cationic iron(III) complex with a hexadentate <i>N</i>₂,<i>N'</i>_2',<i>O</i>₂-aminopyridylphenolate ligand

Abstract

Iron(III) complexation with potentially hexadentate H 2 bbpen (N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-methylpyridyl)ethylenediamine) was studied. The resulting monocationic complex, [Fe(bbpen)] + as its NO 3 - and PF 6 - salts, was characterized by infrared spectroscopy, mass spectrometry, elemental analyses, cyclic voltammetry, and X-ray crystallographic analysis. Crystals of [Fe(bbpen)]NO 3 ·CH 3 OH are monoclinic, space group P2 1 /c, a = 10.2640(13), b = 14.7526(10), c = 18.3172(5) Å, β = 97.904(1)°, and Z = 4. The structure was solved by heavy-atom Patterson methods and refined to an R factor of 0.039 for 3526 reflections with I &gt; 3σ(I). The structure of the [Fe(bbpen)] + cation showed that the ligand is bound in a hexadentate fashion to the central Fe(III) ion, resulting in a distorted octahedral geometry. Magnetic susceptibility measurements indicated the presence of a high-spin Fe(III) ion, and the UV-vis spectrum of [Fe(bbpen)]NO 3 exhibits absorption maxima, λ max , at 575 nm (ε = 5400 M -1 cm -1 ), 323 (8900), and 275 (13 500). The cyclic voltammogram of [Fe(bbpen)]NO 3 showed a quasi-reversible, one-electron process corresponding to [Fe III (bbpen)] + + e - &lt; _ &gt; [Fe II (bbpen)] at -0.47 V vs. SCE.Key words: cationic, iron(III), phenolate, pyridyl, hexadentate.