Until 1960, catalysts based on coordination compounds were little used and they were mainly employed on the laboratory scale. Since then, however, there has been a rapid emergence of new catalytic systems, mainly due to developments in Organometalic Chemistry, due in large part to the use of organometallic complexes (and / or coordination compounds) in three industrially important reactions: the Ziegler, Wacker and Oxo processes. Appropriate combinations of ligands (electronic and stereo effects) strongly influence the structure and the reactivity of catalytically active complexes. With the increasing knowledge of the coordination chemistry, in particular Organometalic Chemistry, it is possible to get the exact structure of the complex which will catalyze a reaction. Nowadays, the use of “clean” chemical reactions is a requirement, not only in the chemical industry, but also in the laboratory. By using highly efficient and selective catalysts it is possible to save energy and raw material, which is the case of complexes of transition metals. In order to understand catalysis by transition metals it is necessary to know the chemistry of the complexes involved: organic reagents are primarily coordinated to the metal as ligands (i.e., are activated) and are then converted to products through various types of reactions. It is therefore necessary to review some fundamental aspects such as structure, binding and reactions of metal complexes to better understand the phenomena involved in catalysis.
catalysis, catalysts, catalytic systems, coordination compounds, organometallic compounds, ligands, coordination sphere, chemical structure, chemical bonds, metal complexes
Universidade Estadual de Campinas, Instituto de Química
João C. de Andrade
Carol H. Collins