Microwave spectrum of cis, trans, trans-propyl nitrite

The microwave spectra of propyl nitrite, CH3CH2CH2ONO, and its 15N isotopic species were observed in a frequency range from 18 to 32 GHz. The ground state a-type R-branch and b-type Q-branch transitions were assigned. They were found to correspond to a cis, trans, trans form (sp, ap, ap form) { τ1(CO-NO) =0°, τ2 (CC-ON) =180°, τ3(CC-CO) =180°}. The following rotational constants for the ground state were determined: The τ0 structure of cis, trans, trans-propyl nitrite was derived from a least-squares fit of these six rotational constants with reasonably assumed parameters for propyl group as shown in Table 4.