Planar Cyclopenten-4-yl Cations: Highly Delocalized π Aromatics Stabilized by Hyperconjugation.

ABSTRACT: Theoretical studies predicted the planar cyclopenten-4-yl cation to be a classical carbocation, and the highest-energy isomer of C₅ H₇ ⁺ . Hence, its existence has not been verified experimentally so far. We were now able to isolate two stable derivatives of the cyclopenten-4-yl cation by reaction of bulky alanes Cp^R AlBr₂ with AlBr₃ . Elucidation of their (electronic) structures by X-ray diffraction and quantum chemistry studies revealed planar geometries and strong hyperconjugation interactions primarily from the C-Al σ bonds to the empty p orbital of the cationic sp² carbon center. A close inspection of the molecular orbitals (MOs) and of the anisotropy of current (induced) density (ACID), as well as the evalua

SUBMITTER: Nees S 

PROVIDER: S-EPMC7589364 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature