Rotational spectroscopy of 2H,3H-perfluoropentane.

The structure of 2H,3H-perfluoropentane, CF 3 CHFCHFCF 2 CF 3 , has been determine by a combination of Chirp-pulsed Fourier transform microwave (CP-FTMW) spectroscopy and cavity FTMW spectroscopy. Of the four possible stereoisomers, only the enantiomeric pair (R,R)/(S,S) were observed experimentally; there was no spectroscopic evidence for the enantiomeric pair (R,S)/(S,R). The conformeric structure of the (R,R)/(S,S) stereoisomer(s) was that of partial helices with C−C−C−C dihedral angles of 12° (helical) and 1° (staggered). [ABSTRACT FROM AUTHOR]