Mechanistic aspects of methane activation promoted by [MO3]+ (M = Mn, Re)

The thermal gas-phase reactions of [MO3](+) (M=Mn, Re) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Upon reaction with methane, [ReO3](+) brings about the generation of the product pairs [Re,O-3,C,H-2](+)/H-2 and [Re,O-2,H-4](+)/CO3 while [MO3](+) only absorbs CH4 upon releasing O-2. Combining experiment and computation it can be concluded that methane is selectively oxidized to CO by [ReO3](+); for [MO3](+)/CH4, however, simple ligand exchange prevails. The associated reaction mechanisms are revealed, and the origins for the rather different behaviors of [MO3](+) (M=Mn, Re) are discussed. (C) 2018 Elsevier B.V. All rights reserved.