title: Matrix isolation and ab initio study of trans-trans and trans-cis dimers of formic acid.
abstract: Six trans-trans and five trans-cis dimeric structures of formic acid (HCOOH) are revealed by ab initio calculations. Four trans-trans and two trans-cis dimers are identified in the IR absorption spectra in argon matrices. The trans-cis dimers are obtained by narrow-band IR excitation of the vibrational transitions of the trans-trans dimers. Two trans-trans (tt3 and tt6) and one trans-cis (tc4) dimer are characterized experimentally for the first time. The tunneling decay rates of two trans-cis dimers (tc1 and tc4) are evaluated at different temperatures. A greater lifetime of the trans-cis dimers at elevated temperatures compared to the cis-monomer suggests that the high-energy conformers can be stabilized upon hydrogen bonding.
authors.affiliation: Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
authors.forename: Kseniya
authors.initials: K
authors.lastname: Marushkevich
authors.forename: Leonid
authors.initials: L
authors.lastname: Khriachtchev
authors.forename: Jan
authors.initials: J
authors.lastname: Lundell
authors.forename: Alexandra
authors.initials: A
authors.lastname: Domanskaya
authors.forename: Markku
authors.initials: M
authors.lastname: Räsänen
mesh_terms: D019281:Dimerization; D005561:Formates / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D005561:Formates; C030544:formic acid