MICROWAVE-SPECTRA OF C2H4 H2O AND ISOTOPOMERS

The rotational spectrum of the ethylene-water complex has been reexamined using Fourier-transform microwave spectroscopy. Several new transitions were observed in the spectrum of the normal isotopic species. All the transitions were split into doublets with a 3:1 relative intensity ratio. Additionally, the spectra of C2H4 . HDO, C2H4 . D2O, C2H4 . (H2O)-O-18, C2H4 . (H2O)-O-17, cis-CHD=CHD . H2O, trans-CHD=CHD . H2O, 1,1-CD2=CH2 . H2O, and CHD=CH2 . H2O were measured. Splitting patterns and relative intensities of the tunneling doublets of the isotopomers are consistent with a high-barrier tunneling pathway which exchanges the two water hydrogen atoms. A second, low-barrier internal rotation of the water about the hydrogen bond is proposed to explain anomalous dipole moment and O-17 nuclear quadrupole coupling results.