Transition-metal catalyzed coupling chemistry is one of the most utilized and powerful synthetic methods available for making fine chemicals. Precious metal catalysts have dominated due to their high activity and fortuitous two-electron redox cycles. However, their high cost and low earth-abundance have prompted more recent focus on base metal systems. First-row metals like nickel has been shown to be quite capable of performing similar and even new transformations. However, unlike precious metals, nickel catalysis tends to suffer from unproductive one-electron pathways which can hinder catalysis.<br/>Pincer ligand frameworks have been shown to be a vital class of ligands in catalysis and study of fundamental reactivity. Main group metalloligand scaffolds have also shown promise in enhancing and turning on new types of reactivity at transition metals (TM), often promoting two-electron chemistry. Among these, Lewis acidic Group 13 metals have garnered much attention due to their ability to act as strong σ-acceptors and potential for ambiphilic character. The work discussed in this seminar will focus on the design, synthesis, and deployment of pincer-type ‘PAlP’ Lewis acid ligands as a new way to facilitate precious metal chemistry in base metal systems. The TM(PAlP) systems possess an open ligand framework which allows direct access to the TM−Al interaction. Furthermore, these systems exhibit diverse modes of cooperative bond cleavage mediated by the two-site TM−Al unit. Rational ligand design and evolution of several bimetallic systems involving base metals will be highlighted.

Bimetallic cooperativity of transition metal–Al pincer complexes for challenging bond activations

ACS Spring 2022

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