Steric Effects In The Catalytic Tandem Isomerization-Hydrosilylation Reaction

The selective synthesis of linear silanes from remote alkenes is reported. Four new silane-thioether bidentate proligands [SiMe2H(o-C6H4SR)] (R=Bu-i, pentyl, benzyl, neopentyl) have been synthesized and used to form unsaturated and cationic 16-electron hydrido-silyl-Rh-III complexes. These compounds are efficient catalysts for the tandem catalytic alkene isomerization-hydrosilylation reaction at room temperature under solvent-free conditions. The different size of the substituent on the sulfur atom results on a difference in the activity of this tandem reaction. Experimental observations demonstrate that the isomerization process is the rate-determining step of this catalytic transformation. This process would be of value to the chemical industry because mixtures of internal aliphatic olefins are substantially cheaper and more readily available than the pure terminal isomers.