Abstract
A series of silica-supported vanadium oxo complexes has been prepared via water-free grafting VOCl 3 onto the silica surface. The obtained materials have been characterized with Raman, diffuse reflectance FTIR (DRIFT) and UV–vis, 51V solid-state NMR and X-ray photoelectron spectroscopies, elemental analysis and N 2 physisorption. The samples with a low vanadium loading (1–5%) have been found to be comprised primarily of the isolated tetrahedral d 0 units ( SiO)V( O)Cl 2, whereas the materials with a higher vanadium content are contaminated with a significant amount of d 1 vanadium species. The silica-supported vanadium complexes act as heterogeneous catalysts for oxo/imido heterometathesis between N-sulfinylamines and carbonyl compounds affording imines and SO 2. Grafting VOCl 3 onto silica leads to a dramatic enhancement of its catalytic activity. A novel water-free express method for preparation of imines of wide range of aldehydes and some ketones has been developed. Noteworthy, this is the first example of transition metal mediated heterometathetical imidation of ketones.
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