Pyrolysis of ethylamine. I. Microwave spectrum and molecular constants of vinylamine

Microwave rotational spectra assignable to gas phase vinylamine (CH2=CHNH2) have been detected in the pyrolysis decomposition products of ethylamine. Stark effect and hyperfine structure measurements have aided the assignment of the spectrum and allow the determination of the 14N nuclear electric quadrupole coupling constants and the electric dipole moment for vinylamine. The spectrum of the first excited inversion vibrational state has been assigned. Relative intensity measurements indicate that the inversion state lies about 65±25 cm−1 above the ground state. The spectral evidence suggests that vinylamine has a nonplanar equilibrium structure with r0(C−N) = 1.40 Å and &CCN = 125°.