Development of alkyne metathesis catalysts
It’s a game of give and take
New Schrock type tungsten alkylidynecomplexes were designed and synthesized through highand low oxidation state routes. In particular, the tungstenalkylidyne complexes 2 and 4 bearing the 1,3-di-tertbutylimidazolin-2-iminato group (ImtBuN) exhibit very highcatalytic activities in alkyne metathesis reactions such asalkyne cross metathesis and ring-closing alkyne metathesis.Through the combination of the strong electron-donatingimidazolin-2-iminato ligand and the electron-withdrawingfluorinated alkoxide groups, a “Push-Pull-Situation” isestablished, which is considered to be responsible for theobserved high catalytic efficiency. DFT calculations havebeen used to explain the experimental results and touncover even more active catalysts.