Degree
Doctor of Philosophy (PhD)
Department
Chemistry
Document Type
Dissertation
Abstract
Abstract
Alkyne metathesis is a powerful synthetic tool, which provides easy access to complex organic molecules in a single-step. It is a dynamic covalent reaction that scrambles alkynes, carbon-carbon triple bonds (C≡C). Molybdenum- or tungsten-alkylidyne (Mo≡C, W≡C) complexes are typically used as catalyst to cleave and reform alkyne bonds. Our goal has been to gain a deeper understanding of the intrinsic differences between functional ligands by the development of novel phenoxide ligands.
In chapter 2 we explore the detailed synthesis of novel phenoxide podand ligands in an effort to identify their mo-alkylidyne complexes. We were able to synthesize a variety of podand derivatives to promote ligand coordination. Unfortunately, we were not able to form the alkylidyne complex, but the knowledge gained aided in the development of new ligands and further catalysts development in our group.
Chapter 3 explored the synthesis of macrocyclic ligands for molybdenum alkylidyne formation. The stability and organized motif of the calixarene was influential in ligand coordination. We were able to isolate and characterize three complexes using X-ray crystallography. With further modulation we have hopes of isolating rarely studied intermediates and establishing a more active catalyst.
The last chapter follows a novel approach to the synthesize a modular pincer ligand. The mailable moiety of the phenol provided our group with a strategy to tune the Lewis acidity of the Mo-alkylidyne, thus optimizing its activity. We wanted to implement electron withdrawing groups and elements of sterics to the tripodal phenoxide moiety established to increase reactivity. The synthesis of this ligand has provided promising results of catalyst formation. The combined knowledge from this project has brought our group closer to developing a novel phenoxide alkylidyne complex active for metathesis.
Date
4-23-2024
Recommended Citation
Stewart, Marvin L. Jr, "Molybdenum Alkylidyne Complexes with Phenoxide Ligands for Alkyne Metathesis" (2024). LSU Doctoral Dissertations. 6411.
https://repository.lsu.edu/gradschool_dissertations/6411
Committee Chair
Semin Lee