| The selective oxidation of organic substrates is a critical transformation in organic chemistry, and palladium catalysts have long been recognized to enable facile turnover using a diverse set of methods. In recent years, innovative aerobic oxidation methods have emerged that utilize molecular oxygen alone to directly oxidize the reduced palladium catalyst. Unfortunately, under catalytic conditions, the events leading to the reoxidation of the reduced palladium catalyst are kinetically invisible. Therefore, the reactivity of molecular oxygen with a group of experimental and computational palladium model complexes, based closely on known oxidation catalysts, has been examined. This report details these studies with the objective of understanding: (1) the formal spin-forbidden reaction of ground-state triplet molecular oxygen with ground-state singlet palladium(0) species and (2) the pathways for aerobic oxidation of hydrido-palladium(II) species. This work is anticipated to provide the foundation for not only future fundamental studies that will continue to probe the relationship between triplet dioxygen and its reactivity with singlet palladium complexes, but also, catalyst design and method optimization that will improve reoxidation rates and catalyst stability. |
