Microwave Spectrum ofcishyphen;Difluoroethylene. Structures and Dipole Moments of Fluoroethylenes

摘要

The microwave spectrum ofcishyphen;difluoroethylene, HFCdblbnd;CHF, has been investigated in the region 17ndash;36 kMc. Observed rotational constants (Mc) for the ground vibrational state of C212H2F2area0=21103.31,b0=5930.35,c0=4622.27; for C13C12H2F2,a0=20752.10,b0=5900.17,c0=4586.92. From these constants a structure is obtained withrCC=1.324 A,rCF=1.337 A,rCH=1.080 A, FCC=122deg;9prime;, and HCC=121deg;16prime;. Rotational constants forv5=1 have also been determined. A dipole moment of 2.42Dis calculated from the Stark effect. Comparison with previously existing data for ethylene, vinyl fluoride, and vinylidene fluoride shows that there is a shortening of both the CF and the CC bonds with increasing fluorine substitution.