σ-Hole Interactions Involving a Group 7 Metal: Close Contacts in Neutral and Anionic Rhenium Derivatives

Some cases of close contacts involving rhenium of perrhenate esters are presented and investigated computationally. The structures and calculated interaction energies confirm the attractiveness of these contacts, which display geometries typical of σ-hole interactions. The short Re···O contacts observed in three crystalline perrhenate salts confirm the general ability of rhenium compounds, both neutral and ionic, to form such interactions.