Catalysis by Heterogenized Metal Polymers: Advances and Prospects

The current status, trends, and a specific role for macroligands in catalysis by heterogenized metallopolymeric complexes are considered. Relations between homogeneous catalysis, enzyme catalysis, and catalysis by heterogenized metal complexes are traced. The effects of various factors on the catalysis of the main reactions used in organic synthesis—hydrogenation, polymerization (in particular, under the action of immobilized metallocene and postmetallocene catalysts), and redox processes (such as the catalysis of oxygenation, hydroperoxide oxidation, epoxidation, and hydroformylation)—are analyzed. In this review, attention is focused on the nondestructive identification of intermediates and catalytically active species in heterogenized systems. Experimental evidence is presented in support of the fact that the high activity, stability, and selectivity of immobilized catalysts are associated with a dramatic inhibition of concerted reactions in the coordination sphere of a transition metal, which result in catalyst deactivation, as well as with substrate enrichment. Prospects for the development of these highly organized hybrid systems and possibilities to consider the main requirements imposed on metal complex catalysis even at the stage of designing them are predicted.