Studies on Synthesis and Catalytic Reactivity of Titanium, Titanium-Scandium and Titanium-Lithium Complexes Incorporating Schiff-base Ligands
|Keywords||Imido-bridged titanium complexes Heterotrimetallic titanium(Ⅳ) andscandium(Ⅲ) complex Alkyne hydro animation Heterometallic titanium and lithiumcomplex|
The thesis mainly focused on the synthesis and catalytic reactivity of titanium, titanium-scandium and titanium-lithium complexes incorporating the Schiff-base ligands. It’s composed of following three parts.Firstly, the Schiff-base Hgand--H2L (H2L=(((1H-pyrrol-2-yl)methylene)amino)-2,3-dihydro-1H-inden-2-ol), were designed and eight titanium complexes Ti(L)2(1),[Ti(L)(NtBu)]2(2),[Ti(L)(NPh)(py)]2(3),[Ti(L)(4-F-PhN)(py)]2·Tol (4-Tol),[Ti(L)(4-Cl-PhN)(py)]2-Tol·THF (5-Tol·THF),[Ti(L)(4-Br-PhN)(py)]2·Tol (6-Tol), Ti(L)2·(phen)(7)(py=pyridine and phen1,10-phenanthroline) and [Ti(L)2][Ti(L)(4-Cl-PhN)(py)]2·Tol (8·Tol) were synthesized. The crystal structures of all complexes were determined by X-ray diffraction and elemental analysis. Complex1was bisligand-coordinated. Complexes2-6were all imido-bridged. Complex7was generated by adding phen to the Ti(NMe2)4/4-Cl-PhNH2/H2L system. A "mixed" complex8was also been synthesised. The stepwise preparations of these complexes reveal that the structures of the titanium complexes chelated by the H2L ligand could be controlled rationally through adding the different equivalent of the H2L ligand and various ancillary ligands. Theoretical calculations were carried out by using density functional theory (DFT) for complexes1,2,5,8and assumed Ti=N bond-containing intermediate. The optimized geometries are n good agreement with the experimental structures.Secondly, a heterotrimetallic titanium(IV) and scandium(III) complex (NMe2)Ti(L)4Sc2Cl(THF)·3THF (10)) chelated by the H2L was determined by X-ray lifraction and elemental analysis. The catalytic activity of10to the alkyne (?)ydroamination reaction and the guanylation of amines was also investigated.Thirdly, a complex Ti2Li(L)(LC4H9)(py2)(NtBu)2-THF(12) was synthesized by the itanium precursor Ti(NtBu)Cl2(py)2and Li2L. The complex was determined by X-ray diffraction and it provided as the starting material for our futher study.