THE SMALL BINDING ENERGIES OF THE NEGATIVE CLUSTER IONS - SF5-(SF6)(1), SF6-(SF6)(1) AND F-(SF6)(N) (N=1 AND 2), IN THE GAS PHASE

摘要

The gas-phase clustering reactions of SF5-, SF6- and F- ions with SF6 were measured using a high-pressure mass spectrometer. The bond energies of SF5-(SF6)(1) and SF6-(SF6)(1) were estimated to be less than or equal to 2.3 kcal/mol. The bond energies of F-(SF6)(n) with n = 1 and 2 were determined to be 5.4 and approximate to 4.1 kcal/mol, respectively. This result indicates that the SF6 molecule is the weakest electrophilic reagent toward F- ever reported. This is mainly due to the exchange repulsion between the negative ions and fluorine atoms surrounding the reactive S atom. The structure of the cluster ion F-(SF6)(1) whose binding energy was surprisingly small was investigated by ab initio MO calculations. [References: 10]