Cationic Terminal Borylenes by Halide Abstraction: Synthesis and Spectroscopic and Structural Characterization of an FeB Double Bond

The synthesis and the spectroscopic and structural characterization of the cationic terminal borylene complex [Cp*Fe(CO)2(BMes)]+ are reported. Halide abstraction from the corresponding bromoboryl species using Na[BAr f4] generates the borylene as the [BAr f4]- salt in ca. 50% yield. Analyses of IR, NMR, crystallographic, and DFT data are consistent with the presence of an FeB double bond.