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

In high-energy collisions between Au(N-3)(4)(-) anions and sodium vapor, electron transfer occurred to produce Au(N-3)(4)(2-) dianions. These were short-lived (sub microsecond) and Coulomb exploded into Au(N-3)(3)(-) and N-3(-) 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(N-3)(4)(-) parent anions. Loss of one or more N-3(.) or N-2 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)(N-3)(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(N)(4)(2-) 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. (c) 2005 Elsevier B.V. All rights reserved.