Silsesquioxanes as synthetic platforms .2. Epoxy-functionalized inorganic-organic hybrid species

The vinyl cubic polyhedral silsesquioxanes (vinylSiO(1.5))(8) and [(vinylMe(2)SiO)SiO1.5](8) were epoxidized using ten equivalents of m-chloroperoxybenzoic acid (m-CPBA) per cube. The [(vinylMe(2)SiO)SiO1.5](8) compound converts, quantitatively, to the octaepoxide, [(epoxyMe(2)SiO)SiO1.5](8) as demonstrated by H-1, C-13, and Si-29 solution NMR, chemical and mass spectral analysis. The (vinylSiO(1.5))(8) cube was likewise fully epoxidized as determined by NMR; however, efforts to isolate it always led to intractable gels. Partial epoxidation was achieved using only three equivalents of m-CPBA. The partially epoxidized compound, when characterized by CI mass spectra, chemical analysis and NMR, was shown to have an average of two epoxy groups per cube. Both polyepoxides readily polymerized in the presence of Lewis acid catalysts or on reaction with simple amines, which suggests their potential as coupling agents in the synthesis of novel inorganic-organic hybrids.