Insights into the Formation of Borabenzene Adducts via Ligand Exchange Reactions and TMSCl Elimination from Boracyclohexadiene Precursors

The bonding properties of borabenzene with various neutral Lewis bases have been investigated. 1-Chloro-4-isopropyl-2-(trimethylsilyl)-2,4-boracyclohexadiene reacts with a number of Lewis basesnotably pyridine, PMe3, PCy3, and PPh3to afford 4-isopropylborabenzene–base adducts. These adducts can undergo ligand exchange to afford new borabenzene complexes. The scope and mechanism of the reaction, as well as the steric and electronic properties of different adducts, were studied experimentally and computationally.