X-ray Spectroscopic Interrogation of Transition-Metal-Mediated Homogeneous Catalysis: Primer and Case Studies

In this perspective, we highlight recent studies that use X-ray spectroscopic methods to identify and elucidate the molecular and/or electronic structures of intermediate and resting transition-metal species implicated in homogeneous catalysis. We begin with a brief survey of the data that can be accessed with these spectroscopic methods, followed by case studies that showcase advances in the interpretation of X-ray spectroscopic data, demonstrate how these methods complement other types of spectroscopy, and call attention to common misconceptions associated with X-ray spectroscopic techniques. In some cases, we suggest research areas in which alternative spectroscopic tools could aid advances. We conclude with an unorthodox perspective on the reactivity of “high-valent” late transition metals on the basis of recent X-ray spectroscopic insights into their chemical bonding.