An Unsymmetrical, Cyclic Diborene Based on a Chelating CAAC Ligand and its Small‐Molecule Activation and Rearrangement Chemistry. Issue 3 (3rd December 2021) - Lu, Wei
Abstract: A one‐pot synthesis of a CAAC‐stabilized, unsymmetrical, cyclic diborene was achieved via consecutive two‐electron reduction steps from an adduct of CAAC and B2 Br4 (SMe2 )2 . Theoretical studies revealed that this diborene has a considerably smaller HOMO–LUMO gap than those of reported NHC‐ and phosphine‐supported diborenes. Complexation of the diborene with [AuCl(PCy3 )] afforded two diborene–Au I π complexes, while reaction with DurBH2, P4 and a terminal acetylene led to the cleavage of B−H, P−P, and C−C π bonds, respectively. Thermal rearrangement of the diborene gave an electron‐rich cyclic alkylideneborane, which readily coordinated to Ag I via its B=C double bond. Abstract : A doubly CAAC‐supported unsymmetrical, cyclic diborene was obtained via an in situ, one‐pot synthesis protocol. This diborene features a small HOMO–LUMO gap. The reactivity of this diborene with small molecules, including [AuCl(PCy3 )], durylborane, white phosphorus (P4 ) and terminal alkynes, as well as the thermal rearrangement chemistry, were investigated.