On March 15, Prof. Martin Oestreich from Technische Universität Berlin was invited to the 142^nd Science Lecture in the College of Science. He gave a lecture themed “ The Cation Shuffle”, which was chaired by Associate Professor Chuan HE of the Department of Chemistry, SUSTech.

The chemistry of silylium ions (R₃Si ) is at the core of this lecture. Prof. Oestreich first introduced the fundamental aspects of their preparation, isolation, and characterization. The generation of silylium ions with Reed’s carborane acids was emphasized as a representative method. Recent developments include a protolysis approach to silylium ions, culminating in synthesizing the 'fat proton' H₃Si .

Subsequently, Prof. Oestreich gave a vivid and exciting introduction to applying these Lewis superacids in catalysis. The shuffle between proton and silylium-ion was displayed in many works, such as catalytically generated Meerwein’s salt-type oxonium ions for Friedel−Crafts C(sp²)−H methylation. This reaction is initiated by counteranion-stabilized silylium or arenium ions, which form Meerwein’s salt-like oxonium ions with methanol as the active methylating agent. Moreover, the proton-into-silylium-into-carbenium-ion generator was shown in his recent representative article “arenium-ion-catalysed halodealkylation of fully alkylated silanes.” In this way, otherwise inert and, as such, less valuable silanes can be converted to heteroleptic silanes with the desired substitution pattern.

Finally, this science lecture ended with excellent work, the superelectrophile silylium/premium ions-catalyzed deuteration of arenes using inexpensive C₆D₆ as the deuterium source under ambient reaction conditions. 

During the interactive Q&A session, both students and faculty enthusiastically raised questions about the introduction of chirality, as well as the potential applications of the silylium ion catalyst. Prof. Oestreich meticulously addressed each query with detailed explanations.

At the end of the lecture, Associate Professor Chuan HE handed an honorary certificate to Prof. Martin Oestreich.