A Microwave Study of Trans-2-Fluoro-3-(Trifluoromethyl)Oxirane

Chosen due to its structural similarity with previously characterized chiral tagging candidates, trans-2-fluoro-3-(trifluoromethyl)oxirane (tFTFO) is a small chiral molecule to be investigated, both theoretically and experimentally, as a potential chiral tagging molecule. With a strong, simple rotational spectrum, tFTFO shows promise for applications in chiral analysis through the conversion of enantiomers into spectroscopically distinct diastereomeric species through noncovalent attachment. Second order Møller-Plesset (MP2) perturbation theory is used to optimize the structure of tFTFO and of its heterodimer with the argon atom, generating rotational constants to guide spectral analysis. The rotational spectrum of tFTFO and of Ar-tFTFO is obtained using Fourier transform microwave spectroscopy from 5.6 to 18.1 GHz. The spectrum is analyzed to determine the rotational constants and many centrifugal distortion constants for the most abundant species and the significantly abundant singly substituted isotopologues of tFTFO and Ar-tFTFO. The rotational constants for both the monomer and the argon complex are then utilized to find the experimental equilibrium and zero-point average structures via Kraitchman analysis and a structure fitting program, respectively. This work shows that the structure of the argon complex is distinct from the structures previously described for the 3,3,3-trifluoro-, 3,3-difluoro-, and 3-fluoro-1,2-epoxypropane species, suggesting that the addition of the lone fluorine atom alters bonding in the epoxy moiety. tFTFO's dimer with a chiral anlyte is also studied to assess its effectiveness as a chiral tag.