Synthesis, structures, and norbornene polymerization behavior of palladium methyl complexes bearing N-heterocyclic carbene-sulfonate ligands

摘要

A series of N-heterocyclic carbene-sulfonate (NHC-sulfonate) palladium methyl complexes 2a d were synthesized from the reaction of NHC-sulfonate ligands with Ag2O and Pd-2(mu-Cl)(2)Me-2(2,6-lutidine)(2) in good yields. All these complexes were fully characterized by H-1 and C-13 NMR, elemental analysis, and high-resolution mass spectrometry (HRMS). The molecular structure of the representative complex 2a was also determined by single-crystal X-ray diffraction analysis. Upon activation with either methyl-aluminoxane (MAO) or [Ph3C](+)[B(C6F5)(4)](-), all the palladium methyl complexes showed excellent catalytic activities [up to 10(8) g of polynorbornene (PNB) (mol of Pd)(-1) h(-1)] in the vinyl polymerization of norbornene. (C) 2016 Elsevier B.V. All rights reserved.