Versatility of silica used as a ligand: Effect of thermal treatments of silica on the nature of silica-supported alkyl tantalum species

The tris(neopentyl)neopentylidene tantalum complex reacts with the silanol groups of silica dehydroxylated at temperatures ranging from 300 to 700°C to form well-defined surface organometallic species. For a silica dehydroxylated at 300°C, the amount of available silanols allows the formation of species 3 linked by two covalent bonds to silica, while the dehydroxylation at 700°C leads to the formation of species 2 with only one covalent bond to silica. Dehydroxylation thus constitutes a way to control the hapticity of silica towards organometallic complexes.