(Co-)polymerization of methylacrylate with NBE/1-hexene by (8-arylimino-5,6,7-trihydroquinolyl)(methyl)palladium chlorides: an approaching mechanism and the polymeric microstructures
A series of methylated palladium chlorides, N-(5,6,7-trihydroquinolin-8-ylidene)arylamino PdMeCl (8-(ArN)-C9H9NPdMeCl, Ar = 2,6-Me2Ph, Pd1; 2,6-Et2Ph, Pd2; 2,6-iPr2Ph, Pd3; 2,4,6-Me3Ph, Pd4; 2,6-Et2-4-MePh, Pd5), has been prepared and fully characterized by 1H NMR, 13C NMR, FTIR spectroscopy, and elemental analysis. The solid state structures of representative complexes Pd3 and Pd4 were unambiguously confirmed by single crystal X-ray diffraction showing a slightly distorted square planar geometry around the palladium metal center. All these complexes have been found to be highly robust catalyst systems showing high catalytic activities toward the homopolymerization of methyl acrylate at elevated temperature (100 °C) and produced PMA with a molecular weight as high as 4121 kg mol−1. In addition, the Pd3 complex has good capability to incorporate norbornene (8.5%) and 1-hexene (12.7%) into the MA polymer chain. The mechanistic studies suggested that the homo(co)polymerization proceeded through a radical pathway.