Synthesis, Characterization And Properties Of Scandium, Gadolinium Complexes Supported By Aryldiimine NCN Pincer Ligands

In this thesis,a series of Scandium complexes supported by aldimine NCN pince ligands and by ketimine NCN pincer ligands were successfully designed,synthesized and characterized.At the same time,Gadolinium complexes beared by ketimine NCN pincer ligands also were synthesized and characterized.Furthermore,catalytic activities of these complexes has been deeply explored in the catalytic polymerization of isoprene and 1,5-hexadiene.Several scandium and gadolinium complexes bearing tridentate aryldiimine NCN pincer ligands ^Ar[NCN^H]ScCl₂?THF?₂?Ar=Ph?1a?;Ar=2,6-Me₂C₆H₃?1b?,Ar=2,6-Et₂C₆H₃?1c?,Ar=2,6-ⁱPr₂C₆H₃?1d?,Ar=p-MeC₆H₄?1e?,Ar=2,4,6-Me₃C₆H₂?1f??,^Ar[NCN^Me]MCl₂?THF?₂?M=Sc,Ar=2,6-Me₂C₆H₃?2b?;M=Gd,Ar=2,6-Me₂C₆H₃?3b?,Ar=2,6-ⁱPr₂C₆H₃?3d??,and ^{iPr Ph}[NCN^Me]ScCl₂?2d?were synthesized via lithiation of the corresponding ligands with ⁿBu Li and subsequent addition of ScCl₃?THF?₃ or GdCl₃ respectively in the third chapter of this paper.Single crystals suitable for X-ray diffraction analysis grew from the mixture of THF and hexane at–30oC within several days as yellow blocks and the solid structures of1c,1d,1f,and 2b were confirmed by X-ray diffraction analysis to be monomeric with N,C,N-tridentate ligands coordinating to the metal center in a typical meridional manner.Apart from 3b and 3d complexes,the rest complexes were well characterized by NMR and all complexes 1a-1f,2b,2d,3b and 3d were well characterized by elemental analysis.At the same time,the 3b and 3d complexes were well characterized by IR owing to paramagnetic complexes.In the fourth chapter of the paper,we also have deeply studied the catalytic activities of these metal complexes in the catalytic polymerization of isoprene and1,5-hexadiene.In addition,the polymers were well characterized by NMR and GPC respectively.In the presence of alkylaluminium and trityl borate,these well-defined complexes showed moderate to high activities in isoprene polymerization affording cis-1,4 enriched polymers?up to 98.3%?.Moreover,the NCN pincer scandium complexes can also catalyze the 1,5-hexadiene polymerization giving methylene-1,3-cyclopentane enriched polymers?MCP content up to 99.3%?.