Matrix isolation and ab initio study of trans-trans and trans-cis dimers of formic acid.
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.
Marushkevich
Kseniya
K
Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
Khriachtchev
Leonid
L
Lundell
Jan
J
Domanskaya
Alexandra
A
Räsänen
Markku
M
D019281:Dimerization; D005561:Formates / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D013816:Thermodynamics
D005561:Formates; C030544:formic acid