Organoactinide complexes of the type Cp2*AnMe2 (An = Th, U) have been found to be efficient catalysts for the hydrosilylation of terminal alkynes. The chemoselectivily and regiospecificity of the reactions depend strongly on the nature of the catalyst, the nature of the alkyne, the silane substituents, the ratio between the silane and alkyne, the solvent and the reaction temperature. The hydrosilylation reaction of the terminal alkynes with PhSiH3 at room temperature produces the trans-vinylsilane as the major product along with the silylalkyne and the corresponding alkene. At higher temperatures the cis-vinylsilane and the double hydrosifylated alkene, in which the two silicon moieties are connected at the same carbon atom, are also obtained. Replacing the pentamethylcyclopentadienyl ligand by the bridge ligation [Me2SiCp2"]2 2[Li]+ (Cp = C5Me4) affords the synthesis of ansa-Me2SiCp-2ThBu2, which was found to react extremely fast for the hydrosilylation of terminal alkynes or alkenes with PhSiH3. Besides the rapidity of the processes using the bridge organoactinide, as compared to Cp*2ThMe2 the chemo- and regio-selectivity of the products were increased allowing the production of only the trans-vinylsilane and the 1-silylated alkane for the hydrosilylation of alkyne and alkene, respectively.
- Coordinative unsaturation
- Terminal alkynes