Events

Designing First-Row Transition Metal Catalysts

Presented by Prof. Christine Thomas
Hosted by Prof. Jack Norton

Abstract:
The formation and cleavage of chemical bonds in catalytic reactions relies on accessible two-electron redox processes that are often challenging for base metals such as first row and early transition metals. Metal-ligand and metal-metal cooperativity provide a potential solution to this challenge by enabling heterolytic bond cleavage processes and/or facilitating redox processes. Both strategies will be discussed, showcasing the many ways that metal-ligand and bimetallic cooperativity can operate and the methods by which cooperativity can be built into catalyst design. A tetradentate bis(amido)bis(phosphine) (PNNP) ligand has been coordinated to iron and cobalt it has been shown that the resulting (PNNP)Fe complex can activate B-H, Si-H, and C-H bonds across the two iron-amide bonds in the molecule without requiring a change in the formal metal oxidation state. In contrast, the (PNNP)Co complex can undergo a post-metallation ligand dehydrogenation processe that renders the ligand redox-active. In the context of metal-metal cooperativity, phosphinoamide-linked early/late heterobimetallic frameworks have been shown to support metal-metal multiple bonds and facilitate redox processes across a broad range of metal-metal combinations and the resulting complexes have been shown to activate small molecules and catalyze organic transformations. Lastly, ligands that remain “innocent” throughout a catalytic transformation can have a profound impact on the reactivity of the bound transition metal fragment: A tridentate pincer ligand featuring a strong π-acceptor has been shown to stabilized low spin electronic configurations with first transition metal centers, leading to catalytic applications in alkene hydrofunctionalization. An overview of all three projects will be presented.

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