Proton-transfer in Methyleneimine Complexed With Formic-acid

The hydrogen-bonded complexes and the proton transfer process between methyleneimine and formic acid have been investigated from a theoretical viewpoint. The structures are fully optimized at the RHF 6-31G level and the corresponding force constant matrix obtained. Complementary computation at 6-31G* and 6-31G** levels as well as MP2 calculations were performed. The 1:1 system presents a single-well potential energy, but a double-well potential energy may be induced by a solvent effect. This solvent-induced effect may be obtained either by adding one extra molecule leading to trimolecular complexes or by immersing the bimolecular complex in the reaction field of a dielectric continuum. This study shows that slightly polar solvents (epsilon greater-than-or-equal-to 2.5) are sufficient to induce the proton transfer.