Abstract The microwave spectrum of Z-prop-2-ynylideneamine, HC C CH NH, has been measured between 26.5 and 40.0 GHz. The species has been made using a variety of techniques, the most convenient being the pyrolysis of dipropargylamine at 940 C. The detection of the three 13 C isotopic species in natural abundance and two deuterated variants, DC C CH NH and HC C CH NH, has enabled a reliable partial ...