Abstract: Combined with the important teaching content of the undergraduate computational chemistry course, this paper presents a quantum chemical computation case study. Using density functional theory (DFT) methods, the electronic structure and frontier molecular orbitals of metal selenium complexes are analyzed to identify potential reactive sites for their reactions with olefins. Reaction pathways are designed, reaction energy barriers are calculated, and the most efficient metal selenium complexes for ethylene separation and purification are predicted. The quantitative and intuitive description of the stereoselectivity of reactions aims to enable students to understand the relationship between chemical reactions and molecular orbital analysis. Additionally, this study enhances students’ comprehension of factors influencing reaction mechanisms and strengthens their understanding and application of fundamental theoretical concepts, such as electronic effects, frontier molecular orbital symmetry, and the principles of molecular orbital interactions.

Key words: Metal selenium complexes, Reaction site selectivity, Orbital interaction, Density functional theory calculation