Electronic and Steric Effects on L‐Lactide Ring‐Opening Polymerization with NSSN‐type Zr(IV) Complexes

Abstract

In this work the mechanism of L‐lactide polymerization promoted by NSSN zirconium complexes was investigated through DFT methods with the aim to understand as the electronic and steric features of the ligand affect the energy reaction. It was observed that the rate determining step of the process is the opening of the L‐lactide ring and that by increasing the steric hindrance, evaluated by changing geometric parameters and topographic steric maps, or the electron‐withdrawing properties of the ligand, the corresponding energy barrier increases. On the other hand, calculations foresee that a small and electron‐releasing substituent on the nitrogen atom of the ligand, such as the methyl group, is desirable in order to obtain NSSN zirconium based catalysts with improved activity in the ROP of the L‐lactide.

%VBur index and steric maps: from predictive catalysis to machine learning

“…As the method continues to advance, it has the potential to revolutionize the fields of chemistry and materials science, leading to new discoveries and advances in various areas. Despite the clear qualitative character of steric maps, 220,221 still currently to quantify, the %V Bur index must be used to quantify, 174,[222][223][224] or in combination, 31,219,225,226 preferentially because it covers both quantitative and qualitative aspects.…”

Ring-Opening Polymerization of rac-β-Butyrolactone Promoted by New Tetradentate Thioether-Amide Ligand-Type Zinc Complexes

“…As part of our research interests [21][22][23][24], we have developed a series of group 4 and aluminum metal complexes featuring tetradentate thioether-amide ligands (NSSNs) and studied their activity in the ROP of cyclic esters [25][26][27]. Since these ligands present an intriguing combination of hard and soft donor groups, we thought that they could match the "borderline" soft Lewis acid character of zinc ions, influencing their reactivity positively.…”