Size- and Charge-State-Dependent Reactivity of Azidoacetonitrile with Anionic and Cationic Rhodium Clusters Rh_n^±

Abstract

Gas-phase reactions of anionic and cationic rhodium clusters with azidoacetonitrile are studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry under near-thermal conditions. All anionic and large cationic clusters react by adding [C2,N2] in consecutive steps, either by forming interstitial carbides and nitrides or by adding two CN groups to the cluster surface. Small cationic clusters behave differently, with the unimolecular decomposition of the azide determining the reactivity. Saturation is identified via the size-dependent efficiency of consecutive reaction steps. The present results are the first study of organic azides on transition metal clusters. The observed selectivity of the reaction is in contrast to the high exothermicity of any reaction with azide species. The cationic cluster reactivity shows a gradual transition from gas-phase to surface-like behavior with increasing cluster size.

Complexation of transition metals by 3-azidopropionitrile. An electrospray ionization mass spectrometry study

“…FT-ICR has also been applied to study the reactivity of azidoacetonitrileáwitháanionicáandácationicárhodiumáclustersá [31].…”

“…So far, azidoacetic acid is the only aliphatic azide for which a surface study of its decomposition has been completed [26];ápreviously,áhydrazoicáacidáhadábeenáinvestigated asáaáprecursoráinásemiconductorápreparationá [27][28][29]. Azidoacetonitrile and other aliphatic azides have also been investigated but the results are still unpublished [30].áRelatedátoáthisáwork,áBalteanuáetáal.á [31]áinvesti-gated gas-phase reactions of rhodium clusters with azidoacetonitrile as a function of cluster size and charge state to explore the reactions and surface-activated decomposition of one aliphatic covalent azide. These studies show that some applications of organic azides involve the interaction with metals, not only in semiconductor preparation but also in the synthesis of imido species in organometallic chemistry.…”

Probing the structures of gas-phase rhodium cluster cations by far-infrared spectroscopy

“…The magnetic moments, 4,5 electric polarizability, 6 and reactivity with a range of small molecules [7][8][9][10][11][12][13][14][15][16] have been investigated, in many instances revealing a significant size dependence of these properties. In several cases, reaction rate measurements on monodisperse cluster samples have suggested multiple reactivities, indicating the presence of multiple forms of clusters of the same size.…”

The infrared spectrum of Au−∙CO2

“…1,2 Surface experiments have recently been able to probe the structure and reactivity of supported monodisperse metal clusters. 8,15,16 Currently, one of the most interesting metals to investigate in the context of catalysis is gold. 11 The partnership between experiment and theory has been particularly fruitful in the interpretation of IR spectroscopy studies to determine the structural properties of metal-containing clusters in the gas phase 2,12,13 as well as on surfaces 4,14 and in rare gas matrices.…”