Methylbismuth: an organometallic bismuthinidene biradical

Abstract

We report the generation, spectroscopic characterization, and computational analysis of the first free (non-stabilized) organometallic bismuthinidene, BiMe. The title compound was generated in situ from BiMe₃ by controlled homolytic Bi–C bond cleavage in the gas phase. Its electronic structure was characterized by a combination of photoion mass-selected threshold photoelectron spectroscopy and DFT as well as multi-reference computations. A triplet ground state was identified and an ionization energy (IE) of 7.88 eV was experimentally determined. Methyl abstraction from BiMe₃ to give [BiMe₂]^• is a key step in the generation of BiMe. We reaveal a bond dissociation energy of 210 ± 7 kJ mol⁻¹, which is substantially higher than the previously accepted value. Nevertheless, the homolytic cleavage of Me–BiMe₂ bonds could be achieved at moderate temperatures (60–120 °C) in the condensed phase, suggesting that [BiMe₂]^• and BiMe are accessible as reactive intermediates under these conditions.