Comprehensive Analysis of Deuterium Isotope Effects on Ionic H3O+…π Interactions Using Multi-Component Quantum Mechanics Methods

J Comput Chem. 2025 Jan 5;46(1):e70000. doi: 10.1002/jcc.70000.

Abstract

Deuterium isotope effects on interaction energies and geometrical parameters in several H3O+(D3O+)ene and H3O+(D3O+)yne complexes, which involve O-H(D)π interactions, have been analyzed using the MP2 level of the multi-component molecular orbital method (MC_MP2), which can incorporate the nuclear quantum effects of light nuclei, such as protons and deuterons. The MC_MP2 calculations revealed that D3O+ replacement reduced the interaction energies of the complexes and induced changes in geometrical parameters. In addition, natural energy decomposition analysis (NEDA) revealed a strong correlation between the H/D isotope effects on the H/Dπ distances and on each energy component.

Keywords: H/D isotope effects; OH…π interaction; natural energy decomposition analysis; nuclear quantum effects.