The rotational spectrum of the most abundant isotopomer of dichlorocarbene, C35Cl2, in its 1A1 ground
electronic state has been recorded using a molecular beam—Fourier transform microwave spectrometer. The CCl2 was generated by flash pyrolysis in a pulsed free jet expansion using CBr2Cl2 or CHCl2COCl as precursors. 43 hyperfine structure lines of 6 rotational transitions were recorded in the frequency range 8–40 GHz. The analysis of the observed spectrum yielded the rotational constants, the complete 35Cl nuclear quadrupole coupling tensor, and the nuclear
spin-rotation interaction constants. In addition, a refined r0 structure of CCl2 was derived.