Metal-Metal Cooperativity in Well-defined Dinuclear Complexes: Understanding the Reactivity of Dicopper and Dicobalt Complexes Using the PNNP Expanded Pincer Ligand

Man-made chemicals - from materials to pharmaceuticals - are everywhere in our modern world. These chemicals need to be produced and to do so, chemists need the right chemical tools. These tools are known as catalysts. Currently, the catalysts that are typically used to make complicated chemicals, such as pharmaceuticals, are often made with rare and expensive metals. Because of the scarcity and cost of these metals, chemists have been looking for ways to use more abundant metals instead. One strategy to enable the use of abundant metals is to have two metal atoms work together in a catalyst. However, very little is known about the reactivity of such dinuclear catalysts, which makes it difficult to rationally design catalysts that have this cooperativity between two metals. In this thesis, the PNNP expanded pincer ligand is used as a rigid framework to hold two abundant metal atoms close to each other. This way, the (potentially cooperative) reactivity of these metals can be studied. Using this approach, it was found that such well-defined catalysts with two metals react very differently from similar catalysts with only one metal. Moreover, it was possible to match the reactivity of these catalyst containing two metals with a reaction in which this specific reactivity is required. In this reaction, the catalyst with two metals therefore outperformed the analogous catalyst with a single metal. These results can help understand how we could design better dinuclear catalysts in the future.