Department of Chemistry Research Seminar - 17 August 2012

Posted on August 03, 2012

Date:     Friday, 17 August 2012

Time:    11:30 - 12:30

Venue: The Avogadro (3.22) – Chemistry Building

 Abstract:

The discovery of cationic α-dimine nickel chloride by Brookhart and co-workers as effective catalysts for ethylene oligomerization and polymerization sparked interest in finding new nitrogen-donor late transition metal catalysts. This has led to a number of new nitrogen-donor late transition metal catalysts for olefin oligomerization and polymerization reactions which include catalysts from pyridylimine, salicylaldimine and iminoquinoline ligands. A new entrant to this family of nitrogen-donor late transition metal catalysts are catalysts supported by pyrazolyl ligands.

Pyrazolyl ligands have been modified by various research groups since Trofimenko first made tris(pyrazolyl)borate ligands precisely because they are tunable electronically and thus capable of providing varied electrophilicity to a metal centre; a property Brookhart finds crucial for α-dimine nickel and palladium complexes to behave as oligomerization or polymerization catalysts.

We have used pyrazolyl ligands to prepare a series of late transition metal complexes, some of which catalyse olefin oligomerization and polymerization reactions; but also have very interesting coordination chemistry. The pyrazolyl ligands offer good electrophilicity to nickel and palladium catalysts but when electrophilicity is high catalysts tend to deactivate. We have devoted a lot of effort to try and find the right balance between catalyst stability and activity. This talk will focus on how ligand design has played a very use role in producing good catalysts and highlight some of the surprises we have come across.

Contact person: Dr. Marilé Landman (012) 420 2527

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