Ab initio study of ion transfer in (H₂CoHOCH₂)⁺ and (H₂COLiOCH₂)⁺

The equilibrium geometry of (H₂COHOCH₂)⁺ is found to have a C_s structure. A double well potential and a 3.49 kcal/mol barrier are found on the study of energetics of proton transfer at a fixed equilibrium interoxygen distance. The equilibrium geometry of the lithium analogue, (H₂COLiOCH₂)⁺, is highly symmetric, D_2h. There is no double well in the Li transfer potential until the two oxygen extremes are elongated 1.2 Å longer than its equilibrium length. The transition barrier turns out to be 1.72 kcal/mol when R(OO) increases to 4.84 Å. The discrepancies for the above trends between proton and lithium ion in formaldehyde dimer complex are further analyzed.