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Zinc and Magnesium Catalysts for the Hydrosilylation of Carbon Dioxide

By Michael Rauch (4432120) and Gerard Parkin (1514329)


The terminal zinc and magnesium hydride compounds, [κ<sup>3</sup>-Tism<sup>Pr<sup>i</sup>Benz</sup>]­ZnH and [Tism<sup>Pr<sup>i</sup>Benz</sup>]­MgH, which feature the tris­[(1-isopropyl­benz­imidazol-2-yl)­dimethylsilyl]­methyl ligand, react with B­(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> to afford the ion pairs, {[Tism<sup>Pr<sup>i</sup>Benz</sup>]­M}­[HB­(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>] (M = Zn, Mg), which are rare examples of these metals in trigonal monopyramidal coordination environments. Significantly, in combination with B­(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, {[Tism<sup>Pr<sup>i</sup>Benz</sup>]­M}-[HB(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>] generates catalytic systems for the hydro­silyl­ation of CO<sub>2</sub> by R<sub>3</sub>SiH to afford sequentially the bis­(silyl)­acetal, H<sub>2</sub>C­(OSiR<sub>3</sub>)<sub>2</sub>, and CH<sub>4</sub> (R<sub>3</sub>SiH = PhSiH<sub>3</sub>, Et<sub>3</sub>SiH, and Ph<sub>3</sub>SiH). In contrast to many other catalysts for these transformations, both the zinc and magnesium catalytic systems are active at room temperature, and the latter provides the first example of catalytic hydro­silyl­ation of CO<sub>2</sub> involving a magnesium compound. Also of note, the selectivity of the catalytic systems may be controlled by the nature of the silane, with PhSiH<sub>3</sub> favoring CH<sub>4</sub>, and Ph<sub>3</sub>SiH favoring the bis­(silyl)­acetal, H<sub>2</sub>C­(OSiPh<sub>3</sub>)<sub>2</sub>

Topics: Biophysics, Biochemistry, Cell Biology, Genetics, Physiology, Pharmacology, Infectious Diseases, Biological Sciences not elsewhere classified, Chemical Sciences not elsewhere classified, Et 3 SiH, Ph 3 SiH, PhSiH 3, Pr, magnesium hydride compounds, bi, CO 2, CH 4, R 3 SiH, hydro, monopyramidal coordination environments, Tism, Benz
Year: 2017
DOI identifier: 10.1021/jacs.7b10776.s007
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Provided by: FigShare
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