ANCHORING RHODIUM(I) ON BENZOYLTHIOUREA-FUNCTIONALIZED SILICA XEROGELS - PRODUCTION OF RECYCLABLE HYDROFORMYLATION CATALYSTS AND THE CRYSTAL STRUCTURE OF THE MODEL COMPOUND [RH(COD)(HBZTU)CL]

摘要

Two benzoylthiourea-functionalized silica xerogels, 4.5SiO(2).SiO3/2(CH2)(3)NHC(S)NHC(O)Ph (XGbztu) and SiO3/2 (CH2)(3)NHC(S)NHC(O)Ph (XGbztu*) have been prepared from (EtO)(3)Si(CH2)(3)NHC(S)NHC(O)Ph by the sol-gel process. They are able to bind rhodium(I) species giving the composite materials Rh/XGbztu and Rh/XGbztu*, which are very active insoluble and recoverable catalysts for the hydroformylation of styrene. The anchored species undergo major changes during the catalytic cycles, particularly in the Rh/XGbztu system, whose isoormal selectivity ratio gradually increased in the first five runs. Furthermore, CH3(CH2)(2)NHC(S)NHC(O)Ph (HBztu) has been studied as a model of the surface binding function. The structure of [Rh(cod)(Hbztu)Cl](1), which represents a suitable molecular model for the anchored complexes, has been determined by X-ray diffraction. [References: 50]