Modern chemical synthesis relies on rare metals to carry out many of its most important reactions, creating challenges in cost, sustainability, and scalability. My research seeks to replace these systems by developing new catalytic strategies based on iron, one of the most abundant elements on Earth. By engineering enzymes that control reactive intermediates with high precision, we have discovered new mechanisms that enable iron to perform transformations traditionally reserved for precious metals. This work explores how such biocatalysts can expand the scope of key reactions, access previously unreachable molecular structures through unique mechanisms, and enable the rational design of new enzymes. Ultimately, this research aims to establish a new framework for catalysis in which sustainable, biologically inspired iron systems can match—and surpass—the capabilities of rare metals.