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

The gas-phase clustering reactions of SF5-, SF6- and F- ions with SF6 were measured using a high-pressure mass spectrometer. The bond energi es 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, respectiv ely. This result indicates that the SF6 molecule is the weakest electr ophilic reagent toward F- ever reported. This is mainly due to the exc hange repulsion between the negative ions and fluorine atoms surroundi ng the reactive S atom. The structure of the cluster ion F-(SF6)(1) wh ose binding energy was surprisingly small was investigated by ab initi o MO calculations.