Solid‐State Umbrella‐type Inversion of a VO₅ Square‐Pyramidal Unit in a Bowl‐type Dodecavanadate Induced by Insertion and Elimination of a Guest Molecule

Abstract

Design of cavities for a target molecule and the elucidation of the corresponding host-guest interactions are important for molecular manipulation. A discrete dodecavanadate bowl, [V₁₂ O₃₂ ]^4- (V12), with an entrance diameter of 4.4 Å and an electron-rich guest at the center of the bowl, was stabilized by electrostatic interactions. A characteristic of V12 is a solid-state polytopal rearrangement during guest elimination and recapture. A guest-free dodecavanadate, [V₁₂ O₃₂ ]^4- (V12-free), was prepared by removal of the guest from CH₂ Cl₂ -inserted V12 under vacuum at 50 °C. Single-crystal X-ray analysis revealed that one of the VO₅ square pyramids at the bottom of V12-free was inverted to fill the void of the bowl cavity. The exposure of V12-free to the guest molecule vapors of CH₂ Cl₂ , 1,2-dichloroethane, MeNO₂ , MeCN, and MeBr resulted in the selective insertion of the guest to reform the guest-inserted V12 structure. Whereas CO₂ could be inserted in the V12 bowl, CH₄ and CO could not.