Design Of New [NXO] (X = N, C) Tridentate Ligands, Synthesis Of Group IVB Metal Compounds And Their Application In Olefin Polymerization

Phenoximine [NNO] complexes and functional [NCO] imidazolium salts are very important precusors in organometallic field. It has been proved that IVB metal complexes based on N,N,O-salicylaldiminate ligands render their unprecedented cat-alytic activites for olefins. N-heterocyclic carbenes(NHCs) can be obtained by depro-tonating [NCO] imidazolium salts. Nucleophilic NHCs show varied reactive proper-ties. In this thesis, a series of novel tianium(IV) olefin home-/co-polymerization cata-lysts bearing [NNO] tridentate ligands were synthesized and characterized. The ef-fects of pre-catalyst structure, molar ratio of Al/Ti, polymeric temperature have been investigated in detail. Morever, migration and cyclization of two series of [NCO] im-idazolium salts were further studied after deprotonating by bases. The products re-sulted from migration and cyclization were characterized. In the end, a family of group4metal complexes bearing the new cyclic ligand were synthesized. The thesis was summarized as below:1. A series of novel tridentate ligands,51a-f,52a,52f, in which substituted salic-ylaldiminato/aminato moiety and an isoindoline are linked by trans-diphenylethylenediamine moiety have been prepared. The red dark titanium complexes53a-f,54a,54f were obtained by treating eight ligands with TiCl4in tolu-ene. The structures of53a and54a were confirmed by X-ray diffraction in the solid state with a distorted octahedral coordination geometry. These titanium complexes can catalyze ethylene (co)polymerization. The steric hindrance and electron-withdrawing effects were benefical for the catalytic activity. The open space of central metal is also useful. The13C NMR analysis of the polymer revealed that the polymer is highly lin-ear polyethylene with no detectable branches and only very low amount of1-hexene was incorparated into the main chain of the polyethylene.2. Six aryloxo/amide functionalized imidazolium salts58a-f were synthesized. A new series of rearranged compounds59b-f were obtained by deprotonating imidazo-lium salts with alkalis. The solid state structures of58a,58b and59b were confirmed by X-ray diffraction. The mechanism of this transformation has not been unequivo-cally established, but one postulate has been proposed. This plausible pathway has been tested by varying the reactive conditions, in situ1H-NMR, DEPT and HSQC analyses.3. A new imidazolopiperazine core64was obtained by reacting complex31with NaH in CH2Cl2. A plausible mechanism to account for the formation of complex64has been postulated. A family of group4metal complexes bearing the new cyclic lig-and were synthesized.