Effect of exo -Polyhedral Substitution on Electron Detachment in closo -Dodecaborate Anions: A Theoretical Study

In the present work, the electron detachment process of closo-dodecaborate anion [B12H12]2– and its monosubstituted derivatives was investigated. All considered derivatives were divided into two main groups: dianionic [B12H11X]2– (X = OH, SH, F) and monoanionic [B12H11Y]− (Y = NH3, CO, NCCH3, OC4H8, SC4H8) systems, along with the [CB11H12]− analogue. A main difference in behavior between the two groups upon electron detachment was revealed. For dianionic derivatives, the exo-polyhedral substituent X (OH, SH, F) takes part in the stabilization of the unpaired electron, facilitating electron loss. In contrast, for monoanionic derivatives the substituent remains uninvolved, and electron loss is energetically more demanding. The oxonium derivative [B12H11OC4H8]− exhibits dual behavior: in the gas phase the unpaired electron is delocalized, as observed for the [B12H11Y]− systems, whereas in the acetonitrile medium it is delocalized akin to the [B12H11X]2– systems.