Cyclic metal(oid) clusters control platinum-catalysed hydrosilylation reactions: from soluble to zeolite and MOF catalysts.

The Pt-catalysed addition of silanes to functional groups such as alkenes, alkynes, carbonyls and alcohols, the hydrosilylation reaction, is a fundamental transformation in industrial and academic chemistry, often claimed as the most important application of Pt catalysts in solution. However, the exact nature of the Pt active species and its mechanism of action is not well understood yet, particularly regarding regioselectivity. Here, experimental and computational studies together with an graphical method show that the hydroaddition of alkynes proceeds through Pt-Si-H clusters of 3-5 atoms (metal(oid) association) in parts per million amounts (ppm), which decrease the energy of the transition state and direct the regioselectivity of the reaction.