Development of alkyne metathesis catalysts: It's a game of give and take

摘要

New Schrock type tungsten alkylidyne complexes were designed and synthesized through high and low oxidation state routes. In particular, the tungsten alkylidyne complexes 2 and 4 bearing the 1,3-di-tert-butylimidazolin-2-iminatq group (lm~(tBu)N) exhibit very high catalytic activities in alkyne metathesis reactions such as alkyne.cross metathesis and ring-closing alkyne metathesis. Through the combination of the strong electron-donating imidazolin-2-iminAto ligand and the electron-withdrawing fluoridated alkoxide groups, a "Push-Pull-Situation" is. established, which is considered to be responsible for the observed high catalytic efficiency. DFT calculations have been used to. explain the experimental results and to uncover even more active catalysts.