Structural and Electrochemical Studies of Novel Bis(μ‐methoxo)diiron complexes: Observation of Fe^IIIFe^IV and Fe^IVFe^IV States Resonating with Phenoxyl Radicals

Abstract

Novel diiron complexes with an Fe2(mu-OMe)2 core were studied as models of the active site of nonheme iron-containing enzymes. X-ray crystal structures of the complexes showed the existence of two types of ligand folding-parallel and twisted-both of which have four virtually equivalent phenolato groups sticking out from the Fe2O2 rhombic plane. Cyclic voltammetry measurements revealed two or more distinct redox waves in a region of relatively high potential, in addition to known Fe(II)/Fe(III) redox waves in a region of lower potential. These new peaks were assigned to the high-valence state of iron atoms, that is, Fe(III)Fe(IV) and Fe(IV)Fe(IV), resonating with the phenoxyl radical(s). The split width of the redox waves ranged from 0.14 to 0.20 eV, which may be a measure of the electronic interaction of the phenolate groups through the Fe2(mu-OMe)2 core.

Structure and Properties of Copper(II), Manganese(III), and Iron(III) Complexes with Potentially Pentaanionic Heptadentate Ligands Including Alkoxido, Amido, and Phenoxido Donors

“…[67] The -2J value for 4 (24.2 cm -1 ) is in the range of those already reported. Accordingly, the geometric parameters of 4 significant for magneto-structural correlations Fe-O methoxido -Fe = 104.2°, planar Fe 2 O 2 ring, Fe···Fe = 3.145 Å are similar to those reported in the literature (Fe-O alkoxido -Fe = 103 and 104.3°, planar Fe 2 O 2 ring in one complex and a dihedral angle of 169°between the Fe-O-O planes in the other, Fe···Fe = 3.106 and 3.144 Å [59] ). A zfs D value of -3.0 cm -1 was found for complex 4.…”

Utilization of a new gold/Schiff-base iron(iii) complex composite as a highly sensitive voltammetric sensor for determination of epinephrine in the presence of ascorbic acid

“…Subcomponent self-assembly approach 43 It is also of notice that observed m-oxo Fe 2 O 2 motif is of relevance with regard to nonheme iron-containing enzymes [44][45][46] and quite unexpectedly herein, it is formed via coordination with adventitious methoxy groups rather than with exploitation of the phenoxy moieties of H 3 L ligand. The latter situation was observed in [Mn 2 (H 2 L) 2 ](ClO 4 ) 2 manganese(II) complex, which we have recently demonstrated to form electrochemical sensor at the Au template with regard to sensing of dopamine in the presence of interfering biogenic compounds.…”

Iron(III) Complexes with Non-Steroidal Anti-Inflammatory Drugs: Structure, Antioxidant and Anticholinergic Activity, and Interaction with Biomolecules

“…Among the Fe–O bond lengths in the coordination sphere, the Fe–O diflunisal bond lengths are the shortest in the coordination sphere (1.920 (2)–1.928 (2) Å) compared to Fe–O methoxo (1.9726 (19)−1.9984 (19) Å), while the Fe–N phen are the longest (2.191 (3)–2.120 (2) Å). The separation distance between the two Fe(III) ions is 3.119 Å and is in the range (3.058–3.24 Å) expected for dinuclear iron(III) complexes bearing two methoxo bridges [ 83 , 84 , 85 , 86 , 87 , 88 ].…”