Ab initio study of intramolecular proton transfer in formohydroxamic acid

Deng Hwa Wu, Jia Jen Ho*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


Interconversion of five isomeric tautomers of formohydroxamic acid via intramolecular proton transfer has been examined by ab initio theoretical calculation. The transfer potential surfaces, the global isomeric structures, and the transition geometries of intramolecular proton transfer were determined by the MP2/6-31+G** level of calculation. The energy was further analyzed by a single point calculation, MP2/6-31++G**//MP2/6-31+G**, and the use of G2 theory. Not counting the unstable charge separating species, the order of stability of these tautomers calculated at the HF level was 1E > 1Z > 2Z > 2E, and it shifted to 1Z > 1E > 2Z > 2E at the MP2 level, where 1Z and 1E are keto forms, while 2Z and 2E are iminol forms. Further investigation using G2 theory redirects the order to be 1Z > 2Z > 1E > 2E. The strength of the intramolecular hydrogen bond and the effect of dipole moment are the two major factors to dominate the acidity of formohydroxamic acid. Judging from the transition barrier of intramolecular proton-transfer we believe that formohydroxamic acid in dissociating proton in the gas phase is an N-acid.

Original languageEnglish
Pages (from-to)3582-3586
Number of pages5
JournalJournal of Physical Chemistry A
Issue number20
Publication statusPublished - 1998 May 14

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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