Electron Transfer and Ligand Addition to Atomic Mercury Cations in the Gas Phase:  Kinetic and Equilibrium Studies at 295 K

Results are reported for experimental measurements of the room-temperature chemical reactions between ground-state Hg•+ ions and 16 important environmental and biological gases: SF6, CO, CO2, N2O, D2O, CH4, CH3F, O2, CH3Cl, OCS, CS2, NH3, C6F6, NO2, NO•, and C6H6. The inductively coupled plasma/selected-ion flow tube tandem mass spectrometer used for these measurements has provided both rate and equilibrium constants. Efficient electron transfer (>19%) is observed with CS2, NH3, C6F6, NO2, NO•, and C6H6, molecular addition occurs with D2O, CH4, CH3F, CH3Cl, and OCS, and SF6, CO, CO2, N2O, and O2 showed no measurable reactivity with Hg•+. Theory is used to explore the stabilities and structures of both the observed and unobserved molecular adducts of Hg•+, and reasonable agreement is obtained with experimental observations, given the uncertainties of the theory and experiments. A correlation is reported between the Hg•+ and proton affinities of the ligands investigated. Solvation of Hg•+ with formic acid was observed to increase the rate of electron transfer from NO• by more than 20%.