A New Domain of Reactivity for High‐Valent Dinuclear [M(μ‐O)₂M′] Complexes in Oxidation Reactions

Abstract

The strikingly different reactivity of a series of homo- and heterodinuclear [(MIII)(μ-O)2(MIII)III]2+ (M = Ni; M′ = Fe, Co, Ni and M = M′ = Co) complexes with β–diketiminate ligands in electrophilic and nucleophilic oxidation reactions is reported, and can be correlated to the spectroscopic features of the [(MIII)(μ-O)2(MIII)III]2+ core. In particular, the unprecedented nucleophilic reactivity of the symmetric [NiIII(μ-O)2NiIII]2+ complex and the decay of the asymmetric [NiIII(μ-O)2CoIII]2+ core through aromatic hydroxylation reactions represent a new domain for high-valent bis(μ-oxido)dimetal reactivity.

From Enzymes to Functional Materials—Towards Activation of Small Molecules

“…[182] Furthermore, heterobimetallic complexes that contain metal-oxygenb ridges were recently shown to be powerful for hydrogen atom transfer reactions (HAT) from hydroxyl groups forming oxygen radicals ( Figure 14). [183,184] Notably,t he second metal center controlled the HATr eactivity of the complexes, showingadecrease in activity according to NiCu > NiNi > NiCo > NiFe. The changes were attributed to a Figure 13.…”

“…Selectiono fliterature reported heterobimetallic compounds for ORR. [182,183,185] decreased nucleophilicity of the second metal anda longside an increased covalent character of the MÀOb ond as well as an increased O!M p-backdonation. In this series, the bimetallic Ni compound 36 allows for nucleophilic oxidations and HATreactions of phenols.…”

“…In this series, the bimetallic Ni compound 36 allows for nucleophilic oxidations and HATreactions of phenols. [183] Likewise, monometallic and bimetallic Fe-, Ni-, Cu-, Co-, and Mn-cyclam complexes allow for OÀOb ond activation and formationo fh igh-valent metal-oxo species. [186][187][188][189][190] Among these complexes, the Co IV -oxo complexes in particular were shown to facilitate CÀHb ond activation, epoxidation of olefins, and oxygen transfer-reactions.…”

“…Moreover,t his is consistentw ith recent literature reports supporting the role of two different metal sites for an efficient oxygen activation by homogeneous systems. [182][183][184] Once again, adopting functionala nd structuralp rinciples of nature, for example, high conductivity,d istinct environment of am etal and specific metal-metal interactions seemt ob eo fh ighi mportance when designing new materials for catalysis.…”

Enhancement of C−H Oxidizing Ability in Co–O2 Complexes through an Isolated Heterobimetallic Oxo Intermediate

“…Many synthetic variants are based on homobimetallic Fe, Co, Ni, and Cu systems, but heterobimetallic complexes featuring O 2 ‐derived ligands are less explored. The groups of Tolman and Driess synthesized reactive heterobimetallic bis(μ‐oxo)dimetal species, which were unstable and were not characterized by X‐ray crystallography . Herein, we describe the synthesis and characterization of an isolable side‐on dioxygen complex of cobalt that serves as a synthon for isolable bimetallic complexes bearing O 2 ‐derived oxo moieties.…”