Theoretical Study on Hydrogen-Tritium Exchange Reactions between Several Organic and HTO Molecules: A Multicomponent QM Study

摘要

Hydrogen-tritium (H-T) exchange reactions between several organic and HTO molecules have been investigated using multicomponent M06-2X (MC_M06-2X)/6-311++G(d,p) method, which can directly take account of the nuclear quantum effect (NQE) of hydrogen nuclei. Transition state (TS) structures on the MC_M06-2X effective potential energy hypersurface are found with the aid of MC_M06-2X-climing image-nudged elastic band method. The relative energies of hydrogen-bonded complexes and the TS structures in hydrogen transfer reactions are clearly lowered by including NQE of proton or triton, while NQE of hydrogen nuclei hardly affects the potential energy profile along C-C or C-O rotational isomerization. Such difference arises from the different behaviors of the changes in spatial distribution of nuclear wave-functions during reactions. Our present study clearly demonstrates that including NQE of hydrogen nuclei is indispensable to adequately analyze H-T exchange reactions between several organic and HTO molecules, or some reaction energy profiles cannot be represented even qualitatively.