A wide variety of synthetic and catalytic reactions rely on close interactions between transition metals with reactive and ancillary ligands. Computational modeling of these metal complexes is now widely used to probe the deeper details of how these interactions lead to productive catalysis. Despite these advances, the impact of ligand flexibility on catalyst stability, rates of reactions, and product selectivity has remained unexplored. Given the relatively significant amount of manual labor associated with generating ligand conformers and their respective complexes, resolving these issues with standard computational methods is highly challenging. This has led to computational studies focusing on using a single conformer for reaction exploration, which may or may not reflect the relevant reaction pathway(s). This can become problematic in studying reactions involving very flexible ligands, e.g. polyolefin chains during polymerization. For example, as the polyolefin chain elongates the number of potential conformers that could exist in-situ grows quickly, and a single conformer no longer can accurately represent the polymer chain. To overcome these challenges and provide greater insight into conformer-dependent reactivity, we have developed a method to systematically generate ligand conformers and metal-ligand complexes. In this talk our new method is used to identify impacts of polymer chain conformation on barriers to polyolefin chain growth. This study provides insight into how ligand flexibility affects catalyst stability and rates of reaction, by revealing dozens of unique transition states spread across the catalyst-ligand conformational space.  <br/>

Impact of ligand conformations on polyolefin growth

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.