Redox cycling at tellurium: Selective and multiple activation of Si–H bonds in common organosilanes and SiH4

Redox catalysis involving the tellurenyl triflate [2‐(tBuNCH)C6H4Te][OTf] was utilized for the activation of the common silanes Et3SiH, Ph4–nSiHn (n = 1 – 3) as well as the difficult‐to‐handle gaseous SiH4. Furthermore, complex siloxanes containing multiple Si−H bonds were converted into siloxylated phenols which are of high interest for the chemical industry. Insights into the catalytical cycle utilizing para‐quinones as both, oxidants and substrates, were provided by identification of key intermediates and by using in situ time‐resolved FTIR spectroscopy, NMR spectroscopy, single‐crystal X‐ray diffraction analysis and DFT calculations. Based on this study, the catalytic cycle is initiated by a Si–H bond activation resulting in the formation of a ditelluride species and the corresponding silyl triflate. In turn, the ditelluride species is first oxidized by the presented quinone, forming an unprecedented tellurium‐based oxonium intermediate, resulting in the formation of the siloxylated phenols and liberation the tellurium catalyst upon subsequent reaction with the silyl triflate. Our proposed catalytic cycle can be generalized for any silane used in this study.