Methylbismuth: an organometallic bismuthinidene biradical

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](center dot) 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 degrees C) in the condensed phase, suggesting that [BiMe2](center dot) and BiMe are accessible as reactive intermediates under these conditions.