Disputas - Master of Science ​​Sahil Gahlawat​

Transition metal (TM) catalysts are indispensable in industrial operations and organic synthesis due to their unique properties, such as variable oxidation states, rich coordination chemistry, and ability to enable electron transfer processes. These properties allow them to activate a diverse range of substrates by lowering activation energies, and the catalysts can be fine-tuned to enhance chemo-, regio-, and stereoselectivities for desired products. One of the prominent and requisite uses of TM catalysts is in the conversion of CO₂ to higher-value products.

With the advent of climate change, scientists are looking for renewable carbon sources to replace fossil fuels. One promising option is CO₂, a non-toxic and highly abundant greenhouse gas. However, the use of CO₂ in chemical synthesis is limited due to its kinetic and thermodynamic stability. TM catalysts have the potential to address these challenges, making the study of these catalysts vital for developing effective CO₂ activation processes. Nonetheless, their complex electronic structures, ligand coordination dynamics, assorted reaction pathways, broad spectroscopic signals, and environmental sensitivity make it difficult to study them experimentally. Computational chemistry, with its explanatory and predictive power, can help elucidate their intricate behaviors and interactions.

In this thesis, I examined TM-mediated processes using computational chemistry techniques, particularly density functional theory (DFT), to identify transient species like intermediates and transition states, and to understand their nuclear and electronic structures. My research included an analysis of the factors leading to enantioenriched carbamate formation from CO₂, catalyzed by an Ir-based complex (Paper I). Another study investigated the CO₂-insertion mechanism into diverse Pd-alkyl complexes and its relationship with the experimentally observed reaction kinetics, in close collaboration with an experimental group from Yale University (Paper II). I also collaborated with Aarhus University to examine diverse mechanistic pathways for a Nicatalyzed aryl-alkyl cross-coupling reaction with CO (originating from CO₂) insertion (Paper III). Additionally, I employed state-of-the-art computational techniques, involving ab initio molecular dynamics simulations (AIMD), to precisely predict ¹⁹F nuclear magnetic resonance (NMR) chemical shifts in a Ni-fluoride complex (Paper IV).