Low coordinate germanium(II) and tin(II) hydride complexes: Efficient catalysts for the hydroboration of carbonyl compounds

This study details the first use of well-defined low-valent p-block metal hydrides as catalysts in organic synthesis. That is, the bulky, two-coordinate germanium(II) and tin(II) hydride complexes, L^†(H)M: (M = Ge or Sn, L^† = -N(Ar^†)(SiPrⁱ ₃), Ar^† = C₆H₂{C(H)Ph ₂}₂Prⁱ-2,6,4), are shown to act as efficient catalysts for the hydroboration (with HBpin, pin = pinacolato) of a variety of unactivated, and sometimes very bulky, carbonyl compounds. Catalyst loadings as low as 0.05 mol % are required to achieve quantitative conversions, with turnover frequencies in excess of 13 300 h^-1 in some cases. This activity rivals that of currently available catalysts used for such reactions.