This thesis describes the synthesis, characterization, and reactivity of transition metal complexes, with a focus on enabling sustainable partial oxidations of organic chemicals using molecular oxygen and water as oxidants. Chapter 2 discusses the development of several new precatalysts for the Aldehyde-Water Shift reaction, the conversion of aldehydes and water to carboxylic acids and H2. These studies resulted in the most selective and active precatalyst to date for the AWS reaction. Also examined were the effects of changing pH and venting reaction headspace on both selectivity and activity. Chapter 3 outlines the synthesis of a novel pincer ligand precursor and its metalation to form AuIII organometallic complexes. Contributing to the growing field of homogeneous Au chemistry, the coordination chemistry and fundamental reactivity of these AuIII pincer complexes was investigated, including ?-hydride elimination and C–H activation reactions. A new AuIII–H was also synthesized, and Chapter 4 provides an overview of its reaction with molecular oxygen to form a AuIII–OOH. Kinetic studies of this reaction provide insight on the mechanism of O2 insertion. Lastly, Chapter 5 outlines a targeted strategy for transferring oxygen from Pd–OOH’s to organic substrates using secondary coordination sphere participation.