Wen-Bo Liu, David P. Schuman, Yun-Fang Yang, Anton A. Toutov, Yong Liang, Hendrik F. T. Klare, Nasri Nesnas, Martin Oestreich, Donna G. Blackmond, Scott C. Virgil, Shibdas Banerjee, Richard N. Zare, Robert H. Grubbs, K. N. Houk, and Brian M. Stoltz, “Potassium tert-Butoxide-Catalyzed Dehydrogenative C−H Silylation of Heteroaromatics: A Combined Experimental and Computational Mechanistic Study”, J. Am. Chem. Soc. 2017, 139, 6867−6879.
In this in-depth study, the researchers investigated the mechanism by which potassium tert-butoxide catalyzes the dehydrogenative coupling of heteroarenes with hydrosilanes to form heteroarylsilanes, which in turn are intermediates that can be used build more complex molecules. As part of this effort, researchers used ReactIR FTIR Spectroscopy to investigate the possible presence of a coordinated silane species. In related research by other groups, it was shown that the reaction of (RO)3SiH with the corresponding KOR (R = alkyl or aryl) results in ﬁvecoordinate hydridosilicate [HSi(OR)4]K. The researchers in this work postulated an analogous pentacoordinated intermediate for their reaction, but NMR studies were unsuccessful at providing confirmation. They report, however, evidence for this pentacoordinate species by monitoring the silylation reaction with ReactIR. The spectrum of this reaction revealed a new peak (2056 cm-1) adjacent to the Si-H stretching band in Et3SiH (2100 cm-1). They postulated this peak is consistent with the elongated Si−H bond, as expected in such pentacoordinate complexes. They also observed that the new peak correlated with silylation product formation and postulated that the formation of penta coordinate silicate is responsible for the observed induction period in the reaction.