Gas-phase structure of 2,2,2-trichloroethyl chloroformate studied by electron diffraction and quantum-chemical calculations

DIEGO M. GIL; ME. E. TUTTOLOMONDO; SEBASTIAN BLOMEYER; CHRISTIAN G. REUTER; NORBERT W. MITZEL; AIDA BEN ALTABEF

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2016 vol. 18 p. 393 - 402

1463-9076

The molecular structure and conformational properties of 2,2,2-trichloroethyl chloroformate,ClC(O)OCH2CCl3 were determined experimentally using gas-phase electron diffraction (GED) andtheoretically based on quantum-chemical calculations at the MP2 and DFT levels of theory.Further experimental measurements such as UV-visible, IR and Raman spectroscopy werecomplemented with the corresponding theoretical studies. All experimental results andcalculations confirm the presence of two conformers namely anti-gauche (C1 symmetry) andanti-anti (Cs symmetry). The conformational preference was rationalised by NBO and AIManalyses. Molecular properties such as ionisation potential, electronegativity, chemical potential,chemical hardness and softness were deduced from HOMO?LUMO analyses. The TD-DFT approachwas applied to assign the electronic transitions observed in the UV-visible spectrum. A detailedinterpretation of the infrared and Raman spectra of the title compound are reported. Usingcalculated frequencies as a guide, IR and Raman spectra also provide evidence for the presence ofboth C1 and Cs conformers.