Vinyl-addition polymerizations of norbornene and methyl methacrylate by the palladium(II) complexes ligated by 2-iminomethylquinoline and 2-iminomethylpyridine derivatives

초록

Novel Pd(II) complexes, namely, [LnPdCl2] (L-n = L-A and L-B), where L-A is (E)-3-methoxy-N-(quinolin-2-ylmethylene)propan-1-amine and L-B is (E)-N-(pyridin-2-ylmethylene)hexan-1-amine, were synthesized and characterized. X-ray diffraction studies revealed distorted square planar geometries around the Pd(II) center in [LnPdCl2] (L-n = L-A and L-B). The catalytic capabilities of the synthesized complexes were tested in vinyl addition polymerization of norbornene (NB) in the presence of the cocatalyst modified methylaluminoxane (MMAO), displaying high activities with conversions >= 94% in chlorobenzene at 25 ?. The complex [LBPdCl2] displayed the highest activity of up to 4.40 x 106 gPNB mol Pd-1 h-1 at 25 ?C, generating insoluble polynorbornene (PNB) at an NB/Al/Pd ratio of 8,000:500:1. In addition, preliminary methyl methacrylate (MMA) polymerization studies of the [LnPdCl2]/MMAO system demonstrated that the activities toward polar vinyl monomer production were in the range of 8.00 x 104 to 8.20 x 10(4) gPMMA mol Pd-1 h(-1) at 60 ?, yielding a high-molecular-weight syndiotactic poly(methyl methacrylate) (PMMA, M-w = 1.89 x 10(6) g mol(-1)).

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