Knowledge Bank

An electron diffraction $study1$ of sulfonyl chloride isocyanate, $SO2ClNCO$, could not make a definitive choice between the system being a single isomer with an SCl-NC dihedral angle of $940$ or a mixture of two isomers having angles of $710$ and $1100$. The microwave spectrum of $SO2ClNCO$ has been investigated between 7 GHz and 26 GHz using both a conventional Stark spectrometer and a Fourier transform spectrometer. The spectra of two isotopic species ($\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">37</mrow>}Cl$) were assigned and the rotational constants and the nuclear quadrupole coupling constants for $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$, $\mathrm{<mrow\; data-mjx-texclass="ORD">37</mrow>}Cl$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N$ were determined. Using the six rotational constants derived from the assignment and parameters relating the $-SO2$ moiety structure from the electron diffraction study and other studies of molecules containing the $SO2$ group, the dihedral angle was found to be $93.860$ (12) and the $\angle NCO=175.68(6).$ This study indicates the existence of only a single isomer at the temperature of the Fourier spectrometer experiment and a nonlinearity of the NCO group as has been observed in other similar systems. The value obtained for $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$, $Xzz-71.6MHz$ indicates a $S-Cl$ bond ionicity of 35%.