Phosphorus containing silsesquioxanes - new opportunities for homogeneous catalysis

Silsesquioxanes have attracted considerable interest as sol. mol. models for silica supported catalysts. They have also been used as nano-scaled scaffolds for immobilized homogeneous catalysts. Research on homogeneous catalysis is largely dominated by phosphorus ligands, with extensive attention for new, easily accessible and modular backbones as well as tailor-made properties for specific transformations. We have set out to combine these two fields and explore the possibilities and synthetic strategies to synthesize sterically constrained, silsesquioxane based, mono- and bidentate phosphites and phosphinites. In order to understand the influence of the silsesquioxane framework on the coordination behavior of these novel P-contg. ligands, we studied their complexation with various transition metals, such as palladium, platinum, molybdenum and rhodium. The resulting complexes were characterized by NMR spectroscopy and by X-ray crystallog. Detailed results will be presented on the various aspects of these novel and attractive ligands, including preliminary catalytic results. [on SciFinder (R)