Microwave Spectrum and Structure of Chlorine Azide

The microwave spectra of four isotopic species of chlorine azide, ClN₃, have been observed in the frequency range 26–48 GHz. From the measured values of the rotational constants, the molecule has been deduced to be planar with the following internuclear parameters: $\mathrm{r(}\mathrm{Cl}–{\mathrm{N}}_{\text{(1)}}\text{)\hspace{0.17em}=\hspace{0.17em}1.745\hspace{0.17em}±\hspace{0.17em}0.005 Å, r(}{\mathrm{N}}_{\text{(1)}}–{\mathrm{N}}_{\text{(2)}}\text{)\hspace{0.17em}=\hspace{0.17em}1.252\hspace{0.17em}±\hspace{0.17em}0.010 Å, r(}{\mathrm{N}}_{\text{(2)}}–{\mathrm{N}}_{\text{(3)}}\text{)\hspace{0.17em}=\hspace{0.17em}1.133\hspace{0.17em}±\hspace{0.17em}0.010 Å, ∠}{\mathrm{ClN}}_{\text{(1)}}{\mathrm{N}}_{\text{(2)}}\text{\hspace{0.17em}=\hspace{0.17em}108°40′\hspace{0.17em}±\hspace{0.17em}30′, ∠}{\mathrm{N}}_{\text{(1)}}{\mathrm{N}}_{\text{(2)}}{\mathrm{N}}_{\text{(3)}}\text{\hspace{0.17em}=\hspace{0.17em}171°56′\hspace{0.17em}±\hspace{0.17em}30′}$ , with Cl and N₍₃₎ trans. Values for the chlorine quadrupole coupling constants were obtained for all isotopic species, and for the most abundant, ³⁵Cl¹⁴N₃, were transformed into the principal field gradient axis system. The values obtained are consistent with the deduced structure.