GAS-PHASE ASSOCIATION REACTIONS OF TRIMETHYLSILYLIUM ((CH3)(3)SI-BASES() WITH ORGANIC)

This article is a review of the gas-phase association reactions of (CH 3)(3)Si+ with organic bases. The reactions are considered under the he adings of the three pressure regimes under which they are studied. ICR and FTICR studies, carried out at pressures of 10(-5) and lower, allo w insights into the stabilizations, collisional and radiative, and dec ompositions of the nascent adducts. At pressures around 2 Torr, chemic al ionization studies demonstrate the utility and limitations of(CH3)( 3)Si+ as a reagent ion, whereas high-pressure mass spectrometric and f lowing afterglow experiments yield information on the thermodynamics o f the association reactions. Information is also obtained on the stabi lization of alkyl and vinyl cations by a (CH3)(3)Si group in a positio n beta to the charge site. High pressure (similar to 1 atmosphere) gam ma-radiolytic experiments give detailed information of the neutral pro ducts formed via the association reactions and also yield relative rat e data for inter- and intramolecular processes that occur in the energ y-rich adducts prior to collisional stabilization and neutralization. The ease of experimentation with R3Si+ in the gas phase is contrasted with the difficulty of its recognition and observation in the condense d phase. (C) 1997 John Wiley & Sons, Inc.