Superhalogen plus anion : A recently discovered anion with the formula

Structures for hypervalent anions KF 3 - and KF 2 - have been optimized at MP4SD(T)(full) and CCSD(T) with both 6-311+G(d) and 6-311+G(3df) basis sets. Anion KF 3 - is T-shaped and KF 2 - is linear. The calculated vertical electron detachment energy (VDE) for KF 3 - (6.83 eV) is higher than that of the classical superhalogen anion KF 2 - (5.52 eV). The lowest dissociation pathways are for KF 3 - , Δ H 0 ° = 23.3 kcal mol−1 (products KF 2 - plus F) and for KF 2 - , Δ H 0 ° = 49.6 kcal mol−1 (products KF plus F−). KF 3 2 - (D3h symmetry) is in a shallow minimum with a barrier to dissociation of 4.5 kcal mol−1 (products KF 2 - plus F−) and an overall exothermicity of 40.6 kcal mol−1.