Comparative ONIOM modeling of 1,3-butadiene polymerization using Nd(III) and Gd(III) Ziegler-Natta catalyst systems

On the base of structural and thermodynamic data using modern methods of quantum chemistry, a comparative theoretical study of the elementary acts of initiation and growth of a polymer chain during the polymerization of 1,3-butadiene was carried out. Ziegler-Natta catalysts based on Nd(III) and Gd(III) were used as polymerization initiators. It was shown that the higher stereospecificity of the action of gadolinium catalytic complexes in comparison with neodymium complexes is due to the increased stability of the anti-form of the pi-allylic terminal structure of the growing polymer chain, and the reduced activity is due to the higher activation energy of the processes of initiation and chain growth.