Reaction pathways for proton exchange between protonated formamide and water

by Kamitakahara, Atsushi; Pranata, Julianto

Ab initio molecular orbital calculations at the RHF/6-31 + G(d) and MP2/6-31 + G(d) level were utilized to explore proton exchange pathways between protonated formamide and water. Three different pathways were found. Two were similar to each other, differing only in the conformation of O-protonated formamide that serves as the starting point. In these pathways, and NH proton was transferred to water, forming an imidic acid-hydronium ion complex as the transition state, followed by back transfer of a different proton leading back to O-protonated formamide and water. In the third pathway, an OH proton of O-protonated formamide was transferred to water, forming a formamide-hydronium ion complex as the transition state. Back transfer of the proton was to the amide nitrogen, leading to N-protonated formamide and water. The torsional profile of the C-N bond in the complex between N-protonated formamide and water was also explored. It was found that rotation around this bond was accompanied by a rotation of the water molecule with twice the period. (C) 1998 Elsevier Science B.V.

Journal of Molecular Structure-Theochem
Start Page
2210-2728; 0166-1280