Structure and electrochemical properties of (μ-O)₂Mn₂(iii,iii) and (μ-O)₂Mn₂(iii,iv) complexes supported by pyridine-, quinoline-, isoquinoline- and quinoxaline-based tetranitrogen ligands

Abstract

Seven new bis(µ-oxo) dimanganese complexes with Mn2(III,III) or Mn2(III,IV) oxidation states were prepared using quinoline- and isoquinoline-based tetraamine ligands. The structures of the ligands include ethylenediamine, trans-1,2-cyclohexanediamine and tripodal amine,...

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.…”

A Synthetic Model for the Possible FeIV2(μ-O)2 Core of Methane Monooxygenase Intermediate Q Derived from a Structurally Characterized FeIIIFeIV(μ-O)2 Complex

“…14,15 Received: August 31, 2021 Published: November 25, 2021 In spite of the above extensive efforts, structurally characterized model systems with diverse reactivity, especially with higher reactivity analogues than those reported, are highly sought after. In this Communication, we present the second example of crystallographic characterization of a [Fe III Fe IV (μ-O) 2 ] complex using simple tripod ligand 3-isoTQA (tris(3isoquinolylmethyl)amine), 16,17 and its electrochemical oxidation to the [Fe IV 2 (μ-O) 2 ] species (Scheme 1). Since the basicity of isoquinoline nitrogen atom (pK a = 5.46 in H 2 O) is much higher than that of the quinoline counterpart (pK a = 4.93) and even higher than pyridine (pK a = 5.23), 18 the use of isoquinoline is expected to support high-valent metal centers.…”