Alkyne Metathesis Catalysts with Fluorinated Alkoxide Podand (FLAP) Ligands

Alkyne metathesis is a potent synthetic tool for organic reactions. Alkyne metathesis typically requires transition metal catalysts, such as those based on molybdenum (Mo) or tungsten (W). The development of alkyne metathesis was hindered for a long time due to a lack of mechanistic understanding of the reaction. However, research involving alkyne metathesis gained momentum earlier in this century as more researchers began studying it. They have learned the impact of the catalysts and ligands in alkyne metathesis reactions. Since then, a plethora of research has been done on developing the catalyst and ligand design.\nIn Chapter 2, we conducted thorough research on the fluorinated alkoxide podand ligands and catalysts. Fluroalkoxy ligand-based catalysts have applications in ROAMP and terminal alkyne metathesis and ligands’ tunability makes them versatile. Our aim in this project is to study the synergistic effect of fluoroalkoxy ligands and the tripodal system. We have explored various synthetic routes for reliably preparing those ligands and catalysts. We have studied their catalytic activity and substrate scope to better understand their full potential.\nIn Chapter 3, we have introduced a novel ligand, silole (silacyclopentadienes), for alkyne metathesis catalyst. Siloles are widely used in organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), chemo, and biosensors for their electron-transporting ability. The reason for their unique properties lies in their electronic structure. We envision employing silole as ligands for Mo(VI)-alkylidyne complexes for alkyne metathesis. In this study, we aim to understand how the low-lying LUMO and electron-withdrawing nature of siloles will affect alkyne metathesis.\nIn Chapter 4, we reported substrate scope study of the Siloxide podand ligand (SiP) and Mo (VI) based alkyne metathesis catalyst to investigate the formation of metallatetrahedrane, MTd. Our hypothesis behind the work is that the noncovalent CH×××p-interactions between the ethyl groups and the ligand phenyl groups are playing important role in stabilizing the unique MTd moiety. To test the hypothesis, we designed a series of substrates with both electron-donating and withdrawing groups to polarize the -CH2- group, which will make the CH×××p interactions stronger.