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, i.e. 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 ad hoc 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. Based on these findings, new extremely-active (ppm) microporous solid catalysts for the hydrosilylation of alkynes, alkenes and alcohols have been developed, paving the way for more environmentally-benign industrial applications. This journal is ; Financial support by MINECO through the Severo Ochoa program (SEV-2016-0683), Excellence program (CTQ 2017-86735-P and CTQ 2017-87974-R) and Retos Col. (RTC-2017-6331-5) is acknowledged. E. P. acknowledges the financial support of the European Research Council under the European Union's Horizon 2020 research and innovation program/ERC Grant Agreement No. 814804, MOF-reactors. M. A. R.-C. thanks ITQ for the concession of a contract and J. O. M. thanks the Juan de la Cierva program for the concession of a contract. We thank V. B. dLL. and N. G. G. for performing degree projects in the ITQ labs. This research was partially supported by the supercomputing infrastructure of Poznan Supercomputing Center. The Electron Microscopy Service of the UPV is also acknowledged.