School of Science Department of Chemistry 6 Computational Studies of Transition Metal-Catalyzed Reactions Supervisor: LIN Zhenyang / CHEM Student: TONG Sin Hang / PHYS Course: UROP 2100, Fall Section 1: Recent mechanistic studies on a C(sp2)-O bond formation reaction suggest that the activation of N2O by Ni complexes may involve an SN2-type attack on oxygen by Ni. However, our previous work indicated that this mechanism could be unfavorable, proposing a new singlet pathway for a similar C(sp³)-O bond formation, with evidence for an alternative biradical pathway. Our latest calculations reveal a more favorable singlet biradical reaction pathway, consistent with our predictions. Notably, the intermediate structures exhibit unusual electronic characteristics, while unconventional mechanisms such as ligand-to-ligand charge transfers were identified. Section 2: While f orbitals are often thought to play a minor role in bonding, recent studies have provided experimental evidence of uranium dihydrogen complexes, revealing an unconventional bonding mode. It has been suggested that the interactions between uranium and dihydrogen only consists of π bonding between uranium f orbitals and the dihydrogen σ* orbital, with no σ bonding present. In contrast, our findings confirm the existence of σ bonding between uranium and dihydrogen. Additionally, substituting dihydrogen with ligands of various π-acidity demonstrates the small crystal field effects on f orbitals. DFT Studies on Mechanisms of Transition Metal-Catalyzed or Mediated Reactions Supervisor: LIN Zhenyang / CHEM Student: TONG Sin Hang / PHYS Course: UROP 3200, Spring Nitrous oxide (N2O) is a potent greenhouse gas and pollutant that poses significant threats to the climate and environment. This has led to increased interest in its capture and decomposition, particularly through coordination chemistry, which excels in small molecule activation and catalysis. This article investigates the coordination chemistry of N2O, focusing on the structure, bonding, and reactivity of its complexes. We start by examining the various coordination modes of N2O and analyzing their bonding characteristics, followed by a summary of fundamental reactions between N2O and coordination compounds, including activation modes and reaction mechanisms. The insights gained from these discussions deepen our understanding of N2O reactivity and mechanisms. Ultimately, this article aims to establish a robust theoretical framework for N2O coordination chemistry, facilitating future advancements in the field.
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