Synthesis And Characterization Of Organolanthanide Complexes Supported By Nitrogen-based Ligands And Their Catalytic Behavior For Polymerization

Twenty-eight organolanthanide complexes supported by nitrogen-based ligands, such as guanidinates, amidinates, P-diketiminates, and arylamides were first synthesized and well characterized. Further X-ray diffraction revealed structural features of 23 complexes. The catalytic behaviors of some organolanthanide complexes were tested.1. Reactions of guanidinate lithium {CyNC[N(SiMe3)2]NCy}Li {(i-PrN)2C[N(SiMe3)2]}Li, and {(i-PrN)2C[N(i-Pr)2]}Li with LnCl3 in 2:1 molar ratio gave {CyNC[N(SiMe3)2]NCy}2Ln(u-Cl)2Li(THF)2 (Ln =Sm (3), Y (4)), {(i-PrN)2C[N(SiMe3)2]}2Ln(u-Cl)2Li(THF)2 (Ln = Nd (5), Yb (6)), and {(i-PrN)2C[N(i-Pr)2]}2Ln(u-Cl)2Li(TMEDA) (Ln = Nd (7), Yb (8)), respectively. All these complexes were characterized by elemental analysis, IR spectroscopy, 'H NMR spectroscopy, and X-ray diffraction. In these complexes, each lanthanide metal is surrounded by two guanidinate ligands and two u-chlorine atoms to display a distorted octahedron coordination geometry.2. {(i-PrN)2C[N(SiMe3)2]}2Ln(u-Cl)}2 (Ln = Nd (9), Y (10)) can be prepared by removing the coordinated LiCl from {(i-PrN)2C[N(SiMe3)2J}2Ln(u-Cl)2Li(THF)2 in refluxing toluene. Complex 9 and 10 were characterized by elemental analysis, IR spectroscopy, 1H NMR spectroscopy. X-ray diffraction of complex 9 revealed that it consists of two edge-shared distorted octahedral {(i-PrN)2C[N(SiMe3)2]}2Nd moieties, and each moiety is bonded together through two chloro bridges.3. Treatments of {(i-PrN)2C[N(SiMe3)2]}2Ln(u-Cl)2Li(THF)2 (Ln = Nd (5), Yb (6)) with two equiv. of MeLi at -78℃ afforded {(i-PrN)2C[N(SiMe3)2]}2Ln(n-Me)2Li(TMEDA) (Ln = Nd (11), Yb (12)) in goodisolated yields. Both complexes were characterized by elemental analysis, IR spectroscopy, 1H NMR spectroscopy, and X-ray diffraction. The lanthanide metals are coordinated by two guanidinate ligands and two jx-methyl groups to form a distorted octahedron coordination geometry.4. Reactions of {{(iPrN)2C[N(SiMe3)2]}2Ln(u-Cl)}2 with two equiv. of LiN(i-Pr)2 at room temperature gave {(i-PrN)2C[N(SiMe3)2]}2LnN(i-Pr)2 (Nd (13), Y (14)) in good yields. Both complexes were characterized by elemental analysis, IR spectroscopy, and 1H NMR spectroscopy. X-ray diffraction revealed complex 14 to be a monomer in the solid state. The geometry of central metal can be best described as a pseudo-pyramid with the four nitrogen atoms of the two chelating bidentate guanidinate ligands forming the base, and the nitrogen atom of N(iPr)2 group defining the vertex.5. Reactions of [CyNC(R)NCy]Li with LnCl3 in 3:1 molar ratios gave [CyNC(R)NCy]3LnnTHF (R = methyl, Ln=Nd (15), Gd (16), Yb (17), n = 0; R = phenyl, Ln = Nd (18), Y (19), Yb (20), n = 2). All these complexes were characterized by elemental analysis and IR spectroscopy. Complexes 17 and 20 were further characterized by X-ray diffraction. The geometries of ytterbium atoms in the two complexes are best described as trigonal planars with each chelating bidentate amidinate ligand occupying one coordination vertex.6. Complexes [PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]LnCl2(THF)2(Ln = Sm (21), Yb (22)) and [p-Cl-PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]LnCl2(THF)2 (Ln = Sm (23), Yb (24)) can be obtained by the reactions of asymmetric p-diketiminate lithium [PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]Li and [p-Cl-PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]Li with LnCl3 in 1:1 molar ratio, respectively. These complexes were characterized by elemental analysis, IR spectroscopy, 1H NMR spectroscopy, and X-ray diffraction. In both complexes, the ytterbium atom is six-coordinated with two nitrogen atoms of the P-diketiminate ligand, two chlorine atoms, and two THF molecules in a distorted octahedron.7. Reactions of [PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]YbCl2(THF)2 (22) and [p-Cl-PhNC(Me)CHC(Me)NC6H3-2,6-i-Pr2]YbCl2(THF)2 (24) formed in situ with equivmola...