Borinium Cations as σ-B-H Ligands in Osmium Complexes

摘要

Borinium cations are fascinating two-coordinate highly electrophilic boron species that adopt structures analogous to those observed for allenes. They are stabilized by two dual-purpose substituents that include both a sterically bulky periphery and a functional group capable of π-bonding to boron. Cations of this type, in which only one substituent is capable of π-bonding, are extremely rare and require an extremely bulky group to afford added protection of the electron-deficient boron center. Thus, an alkyl- and an aryl-substituted borinium cation that are unstable at room temperature and have a tetrameth-ylpiperidino group as the second substituent are known.