Experimental and Theoretical Study of Reactions between Manganese Oxide Cluster Cations and Hydrogen Sulfide

Manganese oxide cluster cations (MnmOn+)-O-18 were prepared by laser ablation and reacted with hydrogen sulfide (H2S) in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H-2 S. The experiments suggest that oxygen-for-sulfur (O/S) exchange reaction to release water took place in the reactor for most of the manganese oxide cluster cations: (MnmOn+)-O-18+H2S ->(MnmOn-1S+)-O-18+(H2O)-O-18. Density functional theory calculations were performed for reaction mechanisms of Mn2O2++H2S, Mn2O3++H2S, and Mn2O4++H2S. The computational results indicate these O/S exchange reactions are both thermodynamically and kinetically favorable, thus in good agreement with the experimental observations. The O/S exchange reactions identified in this gas-phase cluster study parallel similar behavior of related condensed phase reaction systems.