The 9‐Borataphenanthrene Anion.

The 9‐borataphenanthrene anion is easily accessed by deprotonation of a 9,10‐dihydro‐9‐boraphenanthrene and its diverse reactivity is investigated. Alkylation occurs at the carbon atom adjacent to boron, and room temperature hydroboration occurs across the B=C bond. The π‐manifold of the central BC5 ring coordinates to chromium in an η6 fashion while only the B=C unit binds η2 to gold, indicating versatility of the 9‐borataphenanthrene anion as a ligand. Supporting calculations rationalize the reactivity and aromaticity is corroborated by nucleus‐independent chemical shift (NICS) indices. [ABSTRACT FROM AUTHOR]