Chemistry of (and on) Transition Metal Clusters: A Fourier Transform Ion Cyclotron Resonance Study of the Reaction of Niobium Cluster Cations with Nitric Oxide

Abstract

The reactions of niobium cluster cations, Nb(+)(n) (n = 2-19), with nitric oxide have been investigated using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR). The overall reaction rate constants are found to be in reasonable agreement with collision rates calculated using the surface charge capture model. The dominant reaction for small clusters (n <9) involves reaction-induced fragmentation resulting in the loss of either NbO or NbN. By contrast, the main reaction observed for the larger clusters (n> 11) is sequential NO chemisorption. Clusters n = 9, 10 exhibit both extremes of behaviour and are the only clusters upon which there is evidence of NO decomposition with N(2) loss observed whenever multiple NO molecules are co-adsorbed. The rate constants for each process have been determined as a function of cluster size.

Effects of Second-Metal (Al, V, Co) Doping on the NO Reactivity of Small Rhodium Cluster Cations

“…The most remarkable effect of doping is to open a new reaction channel (cluster fragmentation) involving the release of a Rh atom in the reactions of specific clusters, Rh n Al + ( n = 3 and 4) and Rh n V + ( n = 4–6), with NO. Similar cluster fragmentation has been observed for Co n + ( n = 4–12), , Cu n O 2 – ( n = 8, 10, and 12), Cu 9 Al + , Cu n Ti + ( n = 4–14), Cu n V + ( n = 5–11), and Nb n + ( n = 2–10) . The observation of the cluster fragmentation indicates that the excess energy generated upon the adsorption of NO is large enough to release metal atoms from the cluster at least.…”

Stability of Aluminum-Doped Copper Cluster Cations and Their Reactivity toward NO and O2

“…This reaction was also observed with or without release of metal atoms for other bare metal and metal oxide clusters such as Co n + , 38,39 Cu n O 2 − , 24 Nb n + , 40 and Rh n ± . 41,42 The NO adsorption probability, the selective activity toward NO [σ r (NO)/σ r (O 2 )], and the NO decomposition efficiency of Cu n Al + are roughly compared with those of Co n + and Cu n O 2 − , which can be obtained mainly from our previous data.…”

Platinum Group Metal Clusters: From Gas‐Phase Structures and Reactivities towards Model Catalysts

“…Ambiguity can arise because mass spectrometry is only sensitive to the mass‐to‐charge ratio of a complex and not to its structure, making it difficult to determine the state of molecules like carbon monoxide, CO, or nitric oxide, NO, where molecular or dissociative adsorption is possible. In some cases, the products of consecutive reactions17 or the fragmentation of the metal cluster18 can help to determine the adsorption state but spectroscopic methods can provide much more detailed information.…”