The utilization and understanding of catalytic reactions by human beings is a historical process, and the earliest application can be traced back to the fermentation of wine with grain before the B. C. Since the 18th century, many scientists began to study catalytic phenomena and catalytic mechanism. With the continuous development of catalytic science, people begin to realize that catalytic chemistry is very important to the economic development of the whole society. Searching for catalysts with high efficiency and excellent performance has become an important subject. It is known that many coordination complexes could catalyze some special organic or polymerization reactions to some extent. When they are used as catalysts, they have high selectivity and catalytic activity. Therefore, coordination complexes have become an attractive target for catalyst design. Usually, the complexes of group VII metals (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt) are the most important in catalysis.
Electronic configuration of coordination complexes in catalysis
Most catalytic reactions involve catalysts that are transition metal complexes—notably the platinum groups comprising Fe, Ru, Os, Co, Rh, Ir, Ni , Pd, and Pt. The catalytic properties of transition metal complexes are closely related to the electronic configuration of transition metals. Due to the difference in electron configuration, the coordination mode and coordination number of transition metal complexes are affected, which changes the properties such as electron density distribution of the complexes and affects the catalytic reactivity. The electron configurations of the transition metal atoms in question are generally in the range d6 to d10, with the configuration d8 being especially widely represented. Furthermore, the catalytic complexes of interest are generally of the spin-paired or low-spin type—i.e., complexes in which the ligand field splittings are sufficiently large so that the d electrons first fill up (with pairing if necessary) the most stable orbitals available to them before occupying those of higher energy.
The main factors affecting the catalytic performance of the coordination complexes
The coordination complexes occupy a special place among the catalysts in organic chemistry because of their pronounced activity and their variety of properties. The catalytic features of coordination complexes are under the strong influence of their ligands, which, in this way, become a useful tool to control the properties of the catalytic system. The main factors affecting the catalytic properties of coordination complexes are as follows:
- Different kinds of coordination groups have certain effects on the catalyst performance of the coordination complexes.
- The size and shape of the ligands have an influence on the catalytic properties of the coordination complexes.
- The unsaturation of the central metal coordination of the coordination complex is the key to its catalytic activity.
Alfa Chemistry discusses the application of coordination complexes in catalysis from the following aspects: