| abstract |
The present invention provides a novel catalytic system comprising catalysts immobilized on ultra-large mesoporous compositions, and particularly compositions having a large percentage of pores with a mean diameter of at least about 50 Å. Catalysts, such as organometallic complexes can reside in these pores to effect catalytic reactions. Such compositions include silicates covalently bound to a ligand that in turn can covalently bind an organometallic fragment. For asymmetric organometallic catalysts, the catalyst is bound to the mesoporous composition via an achiral ligand. The catalytic reactions include hydrogenation, hydroformylation, carbonylation and carbon-carbon coupling reactions, such as Heck or Suzuki reactions. The present invention provides catalyst for performing asymmetric reactions to achieve products of high stereoselectivities. The present invention also relates to ionically immobilized catalysts. In addition, the large pore sizes of these compositions can be used for polymerization reactions where the pore sizes can be tuned to achieve a particular molecular weight distribution. Other uses of the porous compositions include support materials for combinatorial chemistry. |