The 9<i>H</i>‐9‐Borafluorene Dianion: A Surrogate for Elusive Diarylboryl Anion Nucleophiles

Abstract

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