Executive Summary : | Nitrogenase is a crucial enzyme in nature that catalyzes the biological reduction of N2 to NH3. Researchers have been studying its functionality and mechanism for the N2 reduction reaction, but many aspects remain unknown. Nitrogenase can also reduce non-physiological N- and C-substrates, such as diazene, hydrazine, nitrite, acetylene, and carbon dioxide. This reactivity scope broadens the catalytic potential of nitrogenase and opens new avenues to explore its mechanistic details. Detailed mechanistic knowledge about nitrogenase binding and catalyzing these substrates under benign conditions will guide the design and development of next-generation small-molecule activation catalysts. Understanding the electronic nature of crucial intermediates and stepwise formation mechanism is crucial for molecular catalysis at active site metal clusters. Knowledge about nitrogenase-driven reactions holds potential in advancing biotechnology for energy research involving hydrocarbon production and CO2 reduction. This proposal aims to achieve electronic-level details of the broad nitrogenase chemistry, focusing on the step-wise electron and proton transfer process, electronic understanding of the elusive intermediates, and mechanism of substrate binding and reduction using DFT and QM/MM calculations. The goal is to bridge gaps in understanding mechanistic details and electronic nature of the crucial intermediates of the nitrogenase catalytic cycle and investigate the binding, reduction mechanism, and key intermediates of non-physiological N- and C-substrates that get reduced by nitrogenase. Emphasis will be given to N- and C-substrates that lead to value-added products, such as NH3, HCOOH, and CH4. |