Improved Metathesis Lifetime: Chelating Pyridinyl-Alcoholato Ligands in the Second Generation Grubbs Precatalyst
Jean I. du Toit,
Margaritha Jordaan,
Carlijn A. A. Huijsmans,
Johannes H. L. Jordaan,
Cornelia G. C. E. van Sittert,
Hermanus C. M. Vosloo
Affiliations
Jean I. du Toit
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Margaritha Jordaan
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Carlijn A. A. Huijsmans
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Johannes H. L. Jordaan
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Cornelia G. C. E. van Sittert
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Hermanus C. M. Vosloo
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, Potchefstroom 2520, South Africa
Hemilabile ligands can release a free coordination site “on demand” of an incoming nucleophilic substrate while occupying it otherwise. This is believed to increase the thermal stability and activity of catalytic systems and therefore prevent decomposition via free coordination sites. In this investigation chelating pyridinyl-alcoholato ligands were identified as possible hemilabile ligands for incorporation into the second generation Grubbs precatalyst. The O,N-alcoholato ligands with different steric bulk could be successfully incorporated into the precatalysts. The incorporation of the sterically hindered, hemilabile O,N-ligands improved the thermal stability, activity, selectivity and lifetime of these complexes towards the metathesis of 1-octene. A decrease in the activity of the second generation Grubbs precatalyst was additionally observed after incorporating a hemilabile O,N-ligand with two phenyl groups into the system, while increasing their lifetime.
