Abstract:

 The correlation between thermochemistry and kinetics in the proton transfer reactions of small proton bound clusters has been examined. The results show that these reactions with some neutral bases for thee non-alkyl blocked proton bound clusters such as (C2H5OH)nH+(n=1-3) and (CH3OH)3H+ are intrinscally fast. The reactivity efficienices are controlled by overall reaction free energy changes or equilibrium constants, rather than inhibited by the nature of transition state. Reaction entropy changes have the significant influence on reaction kinetics. A proton switch from the ionic center to the periphery between two intermediates, resulting in the evaporation directly of two or three solvent molecules, is proposed for the reactions of dimers and trimers. The reactivity efficiencies for the alkyl blocked dimers such as (CH3CN)2H+,(CH3OCH3)2H+,(CH3COCH3)2H+ and (CH3COOCH3)2H+ are very low, These reactions are not controlled by overall reaction free changes or equilibrium constants.

Key words: Proton bound cluster, Ion-molecule reaction, Reactivity efficiency, Overall reaction free energy changes Δ_rG_m