The microwave spectrum and molecular structure of Ar-2,3,3,3-tetrafluoropropene

Abstract

The microwave spectra of four isotopologues of the complex formed between argon and 2,3,3,3-tetrafluoropropene are obtained in the 5.6–18.4GHz region using a combination of broadband chirped pulse and Balle-Flygare cavity Fourier transform microwave spectroscopy. The argon atom is determined to occupy a position out of the symmetry plane of the tetrafluoropropene where it can interact most strongly with one of the out-of-plane fluorine atoms of the methyl group, carbon atom C2, and the fluorine atom attached to that olefinic carbon. In contrast to previously studied argon-haloethylene complexes, the argon atom is located almost directly above this latter atom instead of being offset from the atoms in the binding partner. Comparisons with analogous species suggests that the π electrons of the CC double bond play an important, but still not completely understood, role in determining the location of the argon while steric effects lead to strongly conserved distances between argon and the atoms to which it binds.