Identification of the short-lived Au(N3)42− dianion from its Coulomb explosion products

In high-energy collisions between Au(N3)4− anions and sodium vapor, electron transfer occurred to produce Au(N3)42− dianions. These were short-lived (sub microsecond) and Coulomb exploded into Au(N3)3− and N3− with a kinetic energy release of 2.6 ± 0.5 eV. In the product ion spectra, peaks correspond to fragment ions formed from collisionally activated Au(N3)4− parent anions. Loss of one or more N3 or N2 produced AuNn− complexes (n = 1-4, 6, 9-10) whereas complexes with n = 5, 7, and 8 were not detected. These ions can be assigned to gold-nitride-azide complexes Au(N)x(N3)y− (x = 0-2 and y = 0-4). Cationic complexes were measured for n = 1-4 and 6. Sodium vapor collision experiments were also performed for Au(N3)2−, which is generated in situ by the spontaneous reduction of Au(N3)42− and concurrent azide dissociation. In this case there was no clear signature indicative of the formation of a dianion. The formation of dianions cannot be excluded, however, since such ions may decay by electron emission instead of dissociation into two singly charged fragment ions.