Knowledge Bank

Th emicrowave spectrum of butadiene monoxide has been studied in the region 26.5 - 40.0 GHz. About 200 transitions of the typesR, R, P, Q, and have been assigned up to $J=35$. From these the rotational constants and the centrifugal distortion constants (4th and 6th order) were determined. The rotational constants are (in MHz); $A=17367.28$, $B=3128.22$, $C=3043.69$. Stark effect measurements gave $\mu a=0.99D$, $\mu b=1.58D$, $\mu c=0.73D$, $\mu =2.00D$. The rotational constants and the components of the dipole moment clearly indicate that the assigned conformer is the trans form, and this seems to be the predominant species at dry ice temperature.