Structure of the vinyldiazomethyl anion and energetic comparison to the cyclic isomers.

The 351.1 nm photoelectron spectrum of the vinyldiazomethyl anion has been measured. The ion is generated through the reaction of the allyl anion with N2O in helium buffer gas in a flowing afterglow source. The spectrum exhibits the vibronic structure of the vinyldiazomethyl radical in its electronic ground state as well as in the first excited state. Electronic structure calculations have been performed for these molecules at the B3LYP/6-311++G(d,p) level of theory. A Franck−Condon simulation of the X 2A‘‘ state portion of the spectrum has been carried out using the geometries and normal modes of the anion and radical obtained from these calculations. The simulation unambiguously shows that the ions predominantly have an E conformation. The electron affinity (EA) of the radical has been determined to be 1.864 ± 0.007 eV. Vibrational frequencies of 185 ± 10 and 415 ± 20 cm-1 observed in the spectrum have been identified as in-plane CCN bending and CCC bending modes, respectively, for the X 2A‘‘ state. T...