Cluster ions: gas-phase stabilities of no +(CH 3CN) n and NO 2+(CH 3cn) n with n=1–5

Abstract

The gas-phase equilibria of the clustering reactions of NO + and NO 2 + with CH 3CN were measured with a pulsed electron-beam high-pressure mass spectrometer. Thermodynamic quantities, ΔH° n−1, n and ΔS° n−1, n , of the NO +(CH 3CN) n and NO 2 +(CH 3CN) n clusters with n=1–5 were determined. It was found that both clusters with n=3 are relatively more stable toward dissociation. For n=1–4, the thermochemical stabilities of NO +(CH 3CN) n were observed to be slightly higher than those of corresponding NO 2 +(CH 3CN) n . The results suggest a switch of the attacking site on the core ion for the fifth ligand molecule of these clusters at n=4→5. Keywords: Gas-phase equilibria; Bond enthalpies; Cluster ions; High-pressure mass spectrometer