Knowledge Bank

The previously described low resolution microwave $spectrum1$ of $CO2-BF3$ has been examined at high resolution, and additional transition of the complex have been observed. Spectra were recorded for the $\mathrm{<mrow\; data-mjx-texclass="ORD">10</mrow>}BF3-C16O2,11BF3-C16O2,10BF3-C18O2$, and $\mathrm{<mrow\; data-mjx-texclass="ORD">11</mrow>}BF3-C18O2$ isotopic derivatives, and all are well fitted using a simple symmetric top Hamiltonian with anomolously large values of $DJK$. The vibrationally averaged distance between the centers of mass of the monomer units is $3.76\backslash AA$, and the average angle between the $C3$ axis of the $BF3$ and the a-axis of the complex is $18\circ$. Application of the standard intertial analysis gives an unphysical valye of $80\circ$ for the average B-C-O angle, indicating extremely large amplitude motion in the complex. The previosly $reported1$ radio-frequency spectrum is tentatively attributed to a low lying degenerate bending state, the presence of which in the molecular beam suggests a very soft bending potential for the $CO2$ subunit.