Bonding Of Rare-Gas Atoms To Si In Reactions Of Rare Gases With Sif3+

Direct bonding has been observed to occur between SiF3+ and the rare gases xenon, krypton, and argon in the gas phase at low collision energies and, in the case of xenon and krypton, also at high collision energies. The kinetics of low-energy addition have been monitored at room temperature in He buffer gas at 0.35 Torr using the selected-ion flow tube (SIFT) tandem mass-spectrometer technique. An investigation of the energetics of dissociation of the adduct ions in multi-collision induced dissociation experiments revealed the formation of adduct ions at high collision energies. Experimental and theoretical results are presented for the formation and stability of two possible low-energy isomers of the gaseous trifluorosilylxenon cation, F3SiXe+, one formed by the direct bonding of Xe to Si and the other by Xe being attached to one F atom. Two possible high-energy isomers are proposed that contain a Si-Xe-F linkage formed by the insertion of Xe into SiF3+ or a F-Xe-F linkage formed by bond redisposition. The carbon analogue CF3+ did not form adduct ions with Xe under the same experimental conditions. Analogous experimental and theoretical studies are reported for the reactions of SiF3+ with Kr and Ar. Experimental results also are reported for the reaction of SiF3+ with N-2 and O-2.