ScF 2+ and ScHe 3+ : two highly-charged episodes from the gas-phase adventures of scandium

Abstract

Quantum chemical calculations on the thermochemistry of gas-phase ScF 2+ and ScHe 3+ are reported. As the lightest possible closed-shell combinations of a transition metal with a halogen or rare gas atom, the identified species each possess noteworthy attributes. Our calculations show that ScF 2+ is thermodynamically stable; its dissociation to either Sc 2+ + F or Sc + + F + is highly endothermic. Further, ScF 2+ is a plausible exothermic product of a yet-unknown class of electron-detachment reactions which can be described as associative charge doubling: viz., F + + Sc → ScF 2+ + e. The triply-charged species ScHe 3+ appears to be the lightest known thermodynamically stable molecular trication.