Reduction vs. Addition: The Reaction of an Aluminyl Anion with 1,3,5,7‐Cyclooctatetraene

The potassium aluminyl complex K[Al(NONAr)] (NON = NONAr = [O(SiMe2NAr)2]2–, Ar = 2,6‐iPr2C6H3) reacts with 1,3,5,7‐cyclooctatetraene (COT) to give K[Al(NONAr)(COT)]. The COT‐ligand is present in the asymmetric unit as a planar μ2‐η2:η8‐bridge between Al and K, with additional K···π‐aryl interactions to neighbouring 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.

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