A Synthetic Model for the Possible Fe^IV₂(μ-O)₂ Core of Methane Monooxygenase Intermediate Q Derived from a Structurally Characterized Fe^IIIFe^IV(μ-O)₂ Complex

Abstract

A bis­(μ-oxo)­diiron­(IV,IV) complex as a model for intermediate Q in the methane monooxygenase reaction cycle has been prepared. The precursor complex with a [FeIIIFeIV(μ-O)2] core was fully characterized by X-ray crystallography and other spectroscopic analyses and was converted to the [FeIV 2(μ-O)2] complex via electrochemical oxidation at 1000 mV (vs Ag/Ag+) in acetone at 193 K. The UV–vis spectral features, Mössbauer parameters (ΔE Q = 2.079 mm/s and δ = −0.027 mm/s), and EXAFS analysis (Fe–O/N = 1.73/1.96 Å and Fe···Fe = 2.76 Å) support the structure of the low-spin (S = 1, for each Fe) [FeIV 2(μ-O)2] core. The rate constants of the hydrogen abstraction reaction from 9,10-dihydroanthracene at 243 K suggest the high reactivity of these synthetic bis­(μ-oxo)­diiron complexes supported by simple N4 tripodal ligand.

Evaluation of oxygen-containing pentadentate ligands with pyridine/quinoline/isoquinoline binding sites via the structural and electrochemical properties of mononuclear copper(ii) complexes

“…37–41 Recently, isoquinoline has been demonstrated as a pyridine alternative with high electron-donating properties and high crystallization ability. 42–45…”

“…[37][38][39][40][41] Recently, isoquinoline has been demonstrated as a pyridine alternative with high electron-donating properties and high crystallization ability. [42][43][44][45] In contrast to the numerous examples of all-nitrogen compounds, oxygen-containing tetra-and pentadentate ligands have been scarcely investigated. [46][47][48][49][50][51][52] Although the high electronegativity of oxygen in comparison with nitrogen significantly reduces the electron-donating ability of ether oxygen binding sites, careful ligand design of oxygen-containing ligands could be a potential strategy for providing an extended ligand library with unique properties.…”