07/29/2021
By Matthew Gage
The Kennedy College of Science, Department of Chemistry, invites you to attend a doctoral dissertation defense by Malkaye Kpante entitled “Origins of selectivity in metal-mediated allylic activation and in the activation of unactivated C-H bonds.”
The defense will be held on Thursday, Aug. 26 at 9 a.m. via Zoom. Please contact Matthew Gage for meeting information if you are interested in attending.
The committee will be composed of Lawrence M. Wolf (chair), Valeri Barsegov, Marina Ruths, Kumar Jayant and Donald Johnson. A brief abstract is provided below.
Abstract: Transition metal catalyzed allylic substitution often exhibits complex product selectivity patterns which may be further complicated if the isomeric metal-allyl intermediates share a single transition state leading to their formation giving rise to a post-transition state bifurcation (PTSB). In this work, DFT calculations using ab-initio molecular dynamics have been carried out that support the presence of a PTSB in Pd catalyzed allylic halide activation directly influencing product selectivity. The AIMD results along with a minimum energy path (MEP) analysis reveal a strong solvation dependence on the selectivity. Similar PTSBs are predicted to be present in iridium mediated allylic C-H activation which may influence selectivity in substituted or isomerized products. The results are predicted to be highly ligand dependent with only subtle structural modifications.
Also investigated were the origins of selectivity in the activation of unactivated C-H bonds, both by reactive dioxirane reagents and by palladium on a cage-like substrate. Through energy decomposition and other electronic structure analyses, both orbital and electrostatic effects were observed to be controlling depending on the substrate. The results are expected to help guide the development of more selective C-H activating catalysts and reagents.
All interested students and faculty members are invited to attend.