Reduction vs. Addition: The Reaction of an Aluminyl Anion with 1, 3, 5, 7‐Cyclooctatetraene. Issue 5 (28th December 2018)

• Record Type: Journal Article
• Authors: Schwamm, Ryan J.; Anker, Mathew D.; Lein, Matthias; Coles, Martyn P.
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 5(2019)
• Page Start: 1489
• Page End: 1493
• Publication Date: 2018-12-28
• Subjects: aluminyl anion -- COT ligand -- cycloaddition -- isomeric anions -- reduction; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201811675
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The potassium aluminyl complex K[Al(NON Ar )] (NON=NON Ar =[O(SiMe2 NAr)2 ] 2−, Ar=2, 6‐ i Pr2 C6 H3 ) reacts with 1, 3, 5, 7‐cyclooctatetraene (COT) to give K[Al(NON Ar )(COT)]. The COT‐ligand is present in the asymmetric unit as a planar μ2 ‐η 2 :η 8 ‐bridge between Al and K, with additional K⋅⋅⋅π‐aryl interactions to neighboring molecules that generate a helical chain. DFT calculations indicate significant aromatic character, consistent with reduction to [COT] 2− . Addition of 18‐crown‐6 causes a rearrangement of the C8 ‐carbocycle to form the isomeric 9‐aluminabicyclo[4.2.1]nona‐2, 4, 7‐triene anion. Abstract : Uneasy lies the head that wears a crown : The initial product from the reaction of a two‐coordinate aluminyl anion with 1, 3, 5, 7‐cyclooctatetraene (COT) contains the reduced COT‐ligand with pronounced aromatic character. Addition of 18‐crown‐6 to K[Al(NON Ar )(COT)] promotes isomerization of the carbocycle to afford the 9‐aluminabicyclo[4.2.1]nona‐2, 4, 7‐triene anion.