Hydrobismuthation: Insertion of Unsaturated Hydrocarbons into the Heaviest Main Group Element Bond to Hydrogen

The bismuth hydride (2,6-Mes₂H₃C₆)₂BiH (1, Mes = 2,4,6-trimethylphenyl), which has a Bi–H ¹H NMR spectroscopic signal at δ = 19.64 ppm, was reacted with phenylacetylene at 60 °C in toluene to yield [(2,6-Mes₂C₆H₃)₂BiC­(Ph)=CH₂] (2) after 15 min. Compound 2 was characterized by ¹H, ¹³C NMR, and UV–vis spectroscopy, single crystal X-ray crystallography, and calculations employing density functional theory. Compound 2 is the first example of a hydrobismuthation addition product and displays Markovnikov regioselectivity. Computational methods indicated that it forms via a radical mechanism with an associated Gibbs energy of activation of 91 kJ mol^–1 and a reaction energy of −90 kJ mol^–1.