Gas phase ion molecule reactions of organometallic compounds; protonation of selected η6-arenetricarbonylchromium complexes and η6-cycloheptatriene complexes of the Group VI metals with various Brønsted acid reagent ions

η⁶-Arenetricarbonylchromium(0) complexes, (with the η⁶-arene = benzene, toluene, methylbenzoate and acetophenone) and η⁶-cycloheptatrienetricarbonyl complexes of chromium(0), molybdenum(0) and tungsten(0) undergo reactions in the gas phase with the Brønsted acid reagent ions H₃⁺, CH₅⁺, t-C₄H₉⁺, (NH₃)_nH⁺ which depend on the Brønsted acid strengths of these ions and also on the basicity of the metal complexes. Processes which involve either metal or ligand proton attachment, as well as charge exchange, electrophillic addition and rearrangement reactions have been identified. Some comparisons are drawn between these gas phase observations and the solutions phase behaviour of these compounds.