The Role of Charge and Directed Steric Constraints in Polymerization Catalysis Elucidated by Bis(imino)phenoxy and Cyclophane Ni(II) Complexes

Abstract

It’s steric environment and charge are the fundamental parameters that define the catalytic properties of any active site. For late transition metal catalysts, they determine polymer molecular weight and branching, and consequently the materials properties of the products in ethylene polymerization. The influence of the charge alone is usually hard to unravel; most concepts involve not only electronic modification, but suffer from additional influence through (often increased) sterics, or e.g. effects resulting from the use of metal ions compared to a charge alone. The other key parameter in catalysis is the steric environment experienced by the substrate. In square planar coordinated, d8-metal catalysts the apical sites are difficult address. This thesis addresses both issues for the case of the prominent salicylaldiminato Ni(II) catalyst motif by means of an ancillary imine donor that serves as a binding site as well as synthetic linker element.