Microwave spectrum and structure of pentafluorobenzene

The rotational spectrum of pentafluorobenzene has been measured by 480 MHz bandwidth chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy. Measurement of many new transitions of the normal isotopologue (including Q-branch transitions up to J = 11 and R-branch transitions up to J = 12) has allowed the first experimental determination of Watson A-reduction centrifugal distortion constants for this species. In addition, Balle–Flygare FTMW measurements of the four unique 13C substituted isotopologues have allowed a determination of the ring and partial fluorine atom structure of the molecule. Spectroscopic constants for the normal isotopologue are: A = 1480.86496(45) MHz, B = 1030.06911(14) MHz, C = 607.50261(9) MHz, ΔJ = 9.0(7) Hz, ΔK = 65(2) Hz, and δJ = 2.5(4) Hz.

► Rotational spectra of four 13C isotopologues were measured.
► rs and partial r0 structures were determined.
► Centrifugal distortion constants were determined for the normal isotopologue.