Comprehensive Analysis of Deuterium Isotope Effects on Ionic HOπ Interactions Using Multi-Component Quantum Mechanics Methods.

Deuterium isotope effects on interaction energies and geometrical parameters in several HO(DO)ene and HO+(DO)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 DO 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.