Catalytically Active Nickel-Nickel Bonds Using Redox-Active Ligands

Advances in catalytic methodology are limited by the available tools for systematically optimizing catalyst structure. For molecular transition-metal catalysts, this optimization process typically involves two principle parameters: the identity of the active metal center and the environment presented by supporting ligands. In this Account, we highlight our group's efforts to exploit nuclearity as a parameter in catalyst design. We recently reported a binucleating naphthyridine-diimine (NDI) ligand that supports coordinatively unsaturated nickel-nickel bonds across a broad range of formal oxidation states. Taking advantage of ligand-centered redox activity, these dinickel complexes function as robust platforms for catalytic transformations, including hydrosilylation and alkyne cyclotrimerization reactions. Our results collectively demonstrate that nuclearity effects provide a complementary means of modulating the activity and selectivity of transition metal catalysts. 1 Introduction 2 Group 10 Metal-Metal Bonds in Catalysis 3 Dinuclear Nickel Complexes Supported by Redox-Active Ligands 4 Multielectron Redox Transformations at Metal-Metal Bonds 5 Dinuclear Silane Activation and Catalytic Hydrosilylations 6 Selective Alkyne Cyclotrimerization 7 Conclusions