(104d) A New Methodology for Synthesizing Silicate Building Block Supported Mono- and Multi- Nuclear Titanium Catalysts

Titanium silicate catalysts are well known for their high catalytic reactivity in various types of reactions. A new synthetic methodology has been developed to prepare catalysts that display high site homogeneities critical to the high selectivities. By the method of sequential additions Ti catalyst ensembles are dispersed into a rigid, spherosilicate Si8O12 building block (bb) matrix with precisely controlled nuclearity and Si-O-Ti linkages between the bb and catalyst centers. The rigidity of the matrix and precise structure control give rise to the site homogeneity and isolation of all catalyst centers throughout the matrix. In addition to atomically dispersed catalysts in which the number of linkages to building blocks is systematically varied, we have focused on incorporating a multinuclear Ti cluster {Ti4Cl6(μ3-O)2(μ2-OOCPh)6 into silicate matrices. In contrast to atomically dispersed titanosilicate catalysts, the Ti4 based ensemble displaces displays both Ti-O-Si and Ti-O-Ti bonds. The synthesis and characterization of this new type of bb-supported Ti catalysts as well as the properties as single site heterogeneous catalysts will be described.