Synthesis and Structures of N-Heterocyclic Carbene-Sulfonate Ruthenium Complexes and Their Applications in the Ring-Opening Metathesis Polymerization of Norbornene

Abstract

A series of N-heterocyclic carbene-sulfonate (NHC-sulfonate) p-cymene ruthenium complexes (2a-2d) were synthesized in high yields from the reactions of NHC-sulfonate ligands with Ag2O and [(p-cymene)RuCl2]2. All of the complexes were characterized fully by 1H and 13C NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. The molecular structures of 2b and 2d were determined by single-crystal X-ray diffraction analysis. Upon activation with Et2AlCl, the ruthenium complexes 2a-2d showed excellent activities for the ring-opening metathesis polymerization of norbornene and produced polymers with high molecular weights and narrow molecular weight distributions. Complex 2a can also efficiently catalyze the copolymerization of norbornene and cyclooctene. All of the obtained polymers were characterized by 1H and 13C NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). A series of N-heterocyclic carbene-sulfonate ruthenium complexes are synthesized and applied for the ring-opening metathesis polymerization of norbornene and the copolymerization of norbornene and cyclooctene.