"New ruthenium catalysts bearing N-heterocyclic carbene ligands for ATRP"

Xavier Sauvage, Aurore Richel, Sébastien Delfosse, Lionel Delaude, Albert Demonceau, and Alfred F. Noels

journal cover
          source: e-Polymers
            year: 2003
          number: P_021
             doi: not available

Abstract: N-heterocyclic carbenes are divalent carbon species, which are commonly used as neutral, two-electron ligands with a negligible pi-back-bonding tendency. They behave as phosphine mimics, yet they are better sigma-donors and they form stronger bonds to metal centres than most phosphines. Their electronic and steric properties are liable to ample modification simply by varying the substituents on the nitrogen atoms. Therefore, N-heterocyclic carbenes constitute a promising new class of ligands available for catalyst's engineering and fine tuning, and a great deal of attention has been paid to them recently.
We found that the 18-electron complex RuCl2(p-cymene)(PCy3) was a versatile and efficient promoter for the ring-opening metathesis polymerisation of both strained and low-strain cyclic olefins when activated by a suitable carbene precursor such as trimethylsilyldiazomethane. RuCl2(p-cymene)(PCy3) was also an excellent catalyst for ATRP (Atom Transfer Radical Polymerisation) of methyl methacrylate and styrene. Herein, we report preliminary results obtained in ATRP when tricyclohexylphosphine was substituted by an N-heterocyclic carbene ligand.

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