Among the rare-earth catalysts, neodymium-based catalysts are systematically investigated due to their efficiency and versatility. Still, the correlation between the complex structure and the catalytic coordination polymerization is not yet fully established. The discovery of new neodymium catalytic systems that are homogeneous, well-defined, thermally stable, and producing polymers in high yield and stereospecificity is an important research direction. Ziegler–Natta catalysts were developed to polymerize olefins and dienes and showed good activity. Later, lanthanide-based Ziegler–Natta type catalysts were reported for improved stereospecificity and activity for the polymerization of dienes. Out of the lanthanide catalysts reported, neodymium-based catalysts exhibit better catalytic performance for the polymerization of dienes and are also valuable for making vinyl polymers and polycaprolactones. This review discusses various neodymium catalysts for stereospecific polymerization of dienes, vinyl monomers, and ε-caprolactone.
