Reactivity of Hydrosilanes with the CrII/SiO2 Phillips Catalyst: Observation of Intermediates and Properties of the Modified CrII Sites

The reaction of hydrosilanes (both silane and triethylsilane) with CrII/SiO2 catalyst has been investigated in detail by analysis of the gaseous by-products, temperature- and pressure- resolved FT-IR spectroscopy and deuterium exchanges. We found that the reaction proceeds via two steps, passing through intermediates characterized by elongated Si–H bonds and transient Cr-hydride species leading to the release of H2 in the gas phase. These experimental evidence allowed us to advance an hypothesis of the reaction mechanism, which validates our previous proposal for the structure of the modified chromium sites. Furthermore, based on the intermediates of the reaction mechanism, we have also tested the ability of the modified “homogeneous-like” CrII sites toward H2 (D2) activation, demonstrating that, contrarily to the unmodified CrII species, such reactivity is present.