Isolable Si=B Analogue of a Vinyl Halide: A Building Block for Facile Access toward Silicon-Boron Multiple Bonded Species

Compared to the outstanding development in the synthesis of Si-B single bonded species, borylsilanes and their application to organic synthesis, the chemistry of Si=B double bonded species, borasilenes and boratasilenes have only made little progress, first of all, due to the difficulties in accessing such double bonds. Herein we report the synthesis of the first Si=B analogue of a vinyl halide, a bromoboratasilene, via formal borylene insertion to the coordination sphere of a monoatomic Si(0) complex, using a dihaloborane as the borylene source. The treatment of bromoboratasilene toward neutral or anionic Lewis bases gives access to new boratasilenes, all of which were proved to possess significant Si=B double bond character by XRD analysis and DFT calculations. These results demonstrate exciting strategies to synthesize new types of Si=B double bonded species which should further progress the chemistry of boron, silicon-containing molecules. The first Si=B analogue of a vinyl halide which acts as a useful building block for difficult-to-access Si=B double bonded species were synthesized by a formal borylene insertion to the coordination sphere of a Si(0) complex. The adjacent Br group and the vacant 3p(Si) orbital serves as reaction sites toward neutral and anionic nucleophiles for late-stage electronic tuning and synthesis of the first Si=B analogue of a cyclopropene. image