Mateusz Nowicki

Adam Mickiewicz University in Poznan, Poland

Title: Triethylborohydride-Catalyzed Hydrosilylation of Vinylarenes, Vinylsilanes and Allyl Ethers - DFT-Calculated Energy Profiles and Their Correlation with Experimental Yields

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Biography

Mateusz Nowicki graduated maxima cum laude with a degree in chemistry from Adam Mickiewicz University in Poznan, Poland, where he currently continues his academic career as a doctoral candidate. He has been awarded a scholarship by the Minister of Science and Higher Education of Poland for outstanding scientific achievements. His scientific interests involve the application of computational methods based on quantum chemistry, especially density functional theory (DFT), in studying research problems in various branches of chemistry, such as drug chemistry, organometallic chemistry, organophosphorus chemistry, and others. Specifically, Nowicki’s research focuses on the mechanisms of chemical transformations, including catalytic processes, photochemical degradation of drugs and dynamic stereochemistry. His plans for the nearest future include submitting a research proposal to the National Science Centre of Poland and applying for Fulbright Junior Research Award in order to conduct a research project in the United States.

Abstract

The addition of Si–H bond to an unsaturated bond, known as hydrosilylation, is one of the key methods of synthesis that affords organosilicon compounds. Typically the reaction is catalyzed by complexes of precious metals or other transition elements; however, efforts are made to develop less expensive yet active and selective catalysts with organoboron compounds awaking an increasing interest[1-2].

After a successful resolution of the mechanism of triethylborohydride-catalyzed hydrosilylation of styrene and 1,1-diphenylethene with phenylsilane[3], we present energy profiles for analogous reactions of other alkenes and hydrosilanes. We also make an attempt to quantitatively correlate experimental yields recorded for those reactions[1] with computational results.

The results from quantum-mechanical calculations lead us to a number of factors that determine the reactivity of particular alkene-hydrosilane systems. The presence of electron-donating alkyl and alkoxy substituents in the aromatic ring of a vinylarene generally destabilizes both the carbanion, which is one of the intermediates in the reaction, and the silicanion, which is the least stable intermediate on the reaction path. However, the extended aromatic system of 2-vinylnaphtalene stabilizes the intermediates and decreases energy barriers. Steric factors also play a decisive role in some cases; C-Si bond was found to be more difficultly formed in ?-methylstyrene than in styrene. Flat phenyl rings are generally better tolerated (as in 1,1-diphenylethene), although the accumulation of those highly destabilizes the silicanion, reflected in a sharp decrease in experimental yield recorded when triphenylsilane is used.