Chirped-Pulse Fourier Transform Microwave Study of 2,2,2-Trifluoroethyl Formate

The rotational spectra of 2,2,2-trifluoroethyl formate and its three 13C isotopologues have been measured with a molecular-beam-based, chirped-pulsed Fourier transform microwave spectrometer in combination with a conventional Balle. Flygare-type instrument up to 18 GHz. Although abinitio calculations predict the presence of two low-energy conformers (analogous to the trans and gauche forms of ethyl formate), the trans isomer was the only stable conformer observed. The r s geometry of the molecular main carbon frame was precisely derived based on a coplanar heavy-atom backbone of this conformer. ESPs of the two lowest energy conformers were calculated to obtain information about the role of through-space effects on their structures and relative stability.