On a Comparison of the Electron Diffraction and Microwave Spectroscopic Structures for t-Butyl Chloride

An r_z structure for t‐butyl chloride has been determined from previously published microwave rotational constants. The resulting parameters: $r_z(\mathrm{C}–\mathrm{Cl}{\text{) = 1.831 ± 0.015\hspace{0.17em}A}}^o{\mathrm{,\hspace{0.17em}r}}_z(\mathrm{C}–\mathrm{C}{\text{) = 1.525 ± 0.005\hspace{0.17em}A}}^o{\mathrm{,\hspace{0.17em}r}}_z(\mathrm{C}–\mathrm{H}{\text{) = 1.081 ± 0.004\hspace{0.17em}A}}^o$ and $>\mathrm{CCCl}\text{=107.0± 0.7°}$ were found to be in excellent agreement with our recent electron diffraction investigation. It was found that small skeletal differences in the r_z distances resulting from isotopic substitution substantially influenced the structure obtained for the parent molecule. An r_Av structure was also obtained for the molecule by combining the microwave and electron diffraction data. A modified set of Kraitchman's equations for symmetric‐top molecules is also given which includes corrections for isotopic changes in bond lengths. Equilibrium bond lengths for $\mathrm{C}–\mathrm{Cl}$ (1.821±0.006 Å) and $\mathrm{C}–\mathrm{C}$ (1.521±0.004 Å) estimated from the r_Av structure are found to be substantially different from the r₈ parameters for the corresponding bonds, $r_s(\mathrm{C}–\mathrm{Cl}\text{)=1.803± 0.002 Å}$ and $r_s(\mathrm{C}–\mathrm{C}\text{)=1.530± 0.002 Å}$ .