Forging Unsupported Metal-Boryl Bonds with Icosahedral Carboranes

In contrast to the plethora of metal‐catalyzed cross‐coupling methods available for the installation of functional groups on aromatic hydrocarbons, a comparable variety of methods are currently not available for icosahedral carboranes, which are boron‐rich three‐dimensional aromatic analogues of aryl groups. Part of this is due to the limited understanding of the elementary steps for cross‐coupling involving carboranes. Here, we report our efforts in isolating metal‐boryl complexes to further our understanding of one of these elementary steps, oxidative addition. Structurally characterized examples of group 10 M−B bonds featuring icosahedral carboranes are completely unknown. Use of mercurocarboranes as a reagent to deliver M−B bonds saw divergent reactivity for platinum and palladium, with a Pt−B bond being isolated for the former, and a rare Pd−Hg bond being formed for the latter. A mercurial reagent: A mercurocarborane shows divergent reactivity with Pt or Pd precursors, delivering a Pt−B bond in one, and a rare Pd−Hg bond in the other (see scheme).