Tetravalent Tellurium-Based Chalcogen Bond Catalysis in the Transfer Hydrogenation of Quinoline: A Theoretical Study

Chalcogen bond (ChB) catalysis is a significant strategy in organocatalysis due to its modifiable polarity, notable directionality, and the flexibility that aids both binding and dissociation. As an important benchmark reaction, the transfer hydrogenation of quinoline (QNL) is widely used to evaluate the catalytic performance and to explore the relationship between the structure and activity of catalysts. In this work, density functional theory calculations are employed to elucidate the mechanism of the ChB-catalyzed transfer hydrogenation of QNL using Hantzsch ester (HEH) as the hydrogen source. Analysis of the transition state properties in the rate-determining step reveals that the σ-hole of ChB catalysts interacts with the nitrogen lone pairs of HEH, accompanied by charge transfer and rearrangement processes occurring throughout the reaction. Energy decomposition analysis (EDA), together with Natural Bond Orbital (NBO) and quantum theory of atoms in molecules (QTAIM) analyses, reveals that polarization effects predominantly stabilize the chalcogen bond (ChB), thereby lowering the reaction energy barriers. This insight provides a foundation for the rational design of new ChB catalysts.