Abstract
Gas-phase formic acid exists primarily as a cyclic dimer. The mechanism of dimerization has been traditionally considered to be a synchronous process; however, recent experimental findings suggest a possible alternative mechanism by which two formic acid monomers proceed through an acyclic dimer to the cyclic dimer in a stepwise process. To investigate this newly proposed process of dimerization in formic acid, density functional theory and second-order Møller - Plesset perturbation theory (MP2) have been used to optimize cis and trans monomers of formic acid, the acyclic and cyclic dimers, and the acyclic and cyclic transition states between minima. Single-point energies of the trans monomer, dimer minima, and transition states at the MP2/TZ2P+diff optimized geometries were computed at the coupled-cluster level of theory including singles and doubles with perturbatively applied triple excitations [CCSD(T)] with an aug′-cc-pVTZ basis set to obtain an accurate determination of energy barriers and dissociation energies. A counterpoise correction was performed to determine an estimate of the basis set superposition error in computing relative energies. The explicitly correlated MP2 method of Kutzelnigg and Klopper (MP2-R12) was used to provide an independent means for obtaining the MP2 one-particle limit. The cyclic minimum is predicted to be 6.3 kcal/mol more stable than the acyclic minimum, and the barrier to double proton transfer is 7.1 kcal/mol.
Recommended Citation
N. R. Brinkmann et al., "An Alternative Mechanism for the Dimerization of Formic Acid," Journal of Physical Chemistry A, vol. 107, no. 47, pp. 10208 - 10216, American Chemical Society, Nov 2003.
The definitive version is available at https://doi.org/10.1021/jp031043f
Department(s)
Chemistry
International Standard Serial Number (ISSN)
1089-5639
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 American Chemical Society, All rights reserved.
Publication Date
27 Nov 2003
