has been studied as an intramolecular model for the reactivity of the parent azide, largely used for photochemical labelling. The singlet nitrene is trapped by intramolecular cyclization onto the pyrazole nitrogen as well as by the low yield addition of intermolecular nucleophiles (EtOH, Et2NH). Ring expansion to a didehydroazepine is absent. The triplet nitrene abstracts hydrogen (intermolecularly) only