Grafting of Copper(I)-NHC Species on MCM-41: Homogeneous versus Heterogeneous Catalysis

The copper(I) complexes [Cu(X){2,6-diisopropylphenyl-NHC-(CH2)(3)Si(OiPr)(3)}] (X=Cl (2a); I (2b), NHC=N-heterocyclic carbene) have been synthesized and characterized. Furthermore, the structure of 2b has been confirmed by X-ray diffraction studies. Complex 2a has been successfully anchored in MCM-41 to afford 2-MCM-41. The activity of both the homogeneous, 2a, and heterogeneous, 2-MCM-41, catalysts in acetophenone hydrosilylation with HSiEt3 and [3+2] cycloaddition of benzyl azide and phenylacetylene has been investigated. The heterogeneous catalyst exhibits catalytic activity for the cycloaddition reaction though, unexpectedly, shows no catalytic activity for hydrosilylation.