Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Double reduction of the THF adduct of 9<jats:italic>H</jats:italic>‐9‐borafluorene (<jats:bold>1</jats:bold>⋅THF) with excess alkali metal affords the dianion salts M<jats:sub>2</jats:sub>[<jats:bold>1</jats:bold>] in essentially quantitative yields (M=Li–K). Even though the added charge is stabilized through π delocalization, [<jats:bold>1</jats:bold>]<jats:sup>2−</jats:sup> acts as a formal boron nucleophile toward organoboron (<jats:bold>1</jats:bold>⋅THF) and tetrel halide electrophiles (MeCl, Et<jats:sub>3</jats:sub>SiCl, Me<jats:sub>3</jats:sub>SnCl) to form B−B/C/Si/Sn bonds. The substrate dependence of open‐shell versus closed‐shell pathways has been investigated.</jats:p>