Superhalogens and Superalkalis: Bonding, Reactivity, Dynamics and Applications

Abstract

Superhalogens discovered by Gutsev and Boldyrev have electron affinity (EA) exceeding that of halogen. Herein, a comprehensive review of transition metal fluorides (TMFs) having the capability to exhibit superhalogen characteristics has been presented. The results predict that up to six or seven F atoms can bind with a single transition metal atom resulting in an increase of EA of given molecules. The EA value generally increases successively in each TMF complex series as the number of F atoms gets increased, reaching a peak value of 9.05 eV (for RhF7) amongst all the reviewed TMFs. By using dissociation energy analysis of these clusters, their stability, and reactivity have also been analysed. It is found that, in general, the energy required for dissociation of these complexes to F2 molecules is higher as compared to the energy required for dissociation to F atoms. The same implies that subject TMFs are stable against dissociation to F2 molecules. Further, bond length variation analysis has been performed for neutral and anionic clusters to understand the effect of charges and the effect of increasing F atoms on bonds in subject TMFs. Detailed EA analysis has also been performed to understand the superhalogen character of TMFs.