Synthesis And Characterization Of Organolanthanide Aryloxo Complexes Supported By β-diketiminate Ligand And Their Catalytic Behavior

Binuclear and mononuclear organolanthanide aryloxo complexes supported byβ-diketiminate ligand can be selectively synthesized by a choice of reaction solvents. These complexes were characterized by X-ray diffraction. The catalytic behaviors of some of these complexes were tested including the polymerization ofε-caprolactone (ε-CL) and L-lactide (L-LA), as well as guanylantion of amines to carbodiimide. The main results obtained are as follows:1. Reaction of [(DIPPh)₂nacnac]LnCl₂(THF)₂((DIPPh)₂nacnac= N,N-diisopropylphenyl-2, 4-pentanediimineanion) with Na(OAr)(OAr = 2,6-diisopropylphenoxide) in 1:1 molar ratio in THF gave the mononuclear organolanthanide aryloxo complexes : [(DIPPh)₂nacnac]Ln(OAr)Cl(THF)(Ln=Yb(1),Y(2)). Complex 1 was characterized by elemental analysis and IR spectroscopy and X-ray diffraction. Complex 2 was characterized by 1HNMR. Complex 1 was found to be the controllable initiators for ring-opening polymerization ofε-CL and L-LA .2. Reaction of [(DIPPh)₂nacnac]LnCl₂(THF)₂ (Ln=Yb, Sm, Nd), respectively, with Na(OAr)(OAr=2,6-diisopropylphenoxide) or Na(OAr")(OAr"= 2,6-di-tert-butyl-phenoxide ) in 1:2 molar ratio in THF gave the mononuclear bisaryloxides complexes : [(DIPPh)₂nacnac]Yb(OAr)₂ (3) , [(DIPPh)₂nacnac]Nd(OAr")₂ (4) , [(DIPPh)₂nacnac]Nd(OAr)₂ (5) , [(DIPPh)₂nacnac]Sm(OAr)₂ (6) . Reaction of Nd(OAr')₂Cl·2THF(OAr'=2,6-Dimethylphenoxide) with [(DIPPh)₂nacnac]Na in 1:1 molar ratio in THF gave the mononuclear bisaryloxides complex : [(DIPPh)₂nacnac]Nd(OAr')₂?THF (7). These complexes were characterized by elemental analysis and IR spectroscopy and X-ray diffraction. Complex 3 was found to be the novel initiators for ring-opening polymerization ofε-CL and L-LA with highly initiatory activity . Complexes 3 showed much more highly activity, but gave the polymers with broad polydispersities. The guanylation of amines with carbodiimide with complexes (3), (4), (5), (6), (7) as catalysts were studied. The results demonstrated that these complexes are efficient catalysts for the guanylation reaction. The systems have the advantage of tolerance to various substrates.3. Reaction of [(DIPPh)₂nacnac]Yb(THF)(μ-Cl)₃Yb(Cl)[(DIPPh)₂nacnac] with Na(OAr')(OAr'=2,6-Dimethylphenoxide) or Na(OAr)(OAr=2,6-diisopropylphenoxide) in 1:1 molar ratio in Toluene gave the binuclear organolanthanide aryloxo complexes {[(DIPPh)₂nacnac]Yb(OAr')(μ-Cl)₃Yb[(DIPPh)₂nacnac](THF)} (8), {[(DIPPh)₂nacnac]Yb(OAr)(μ-Cl)₃Yb[(DIPPh)₂nacnac](THF)} (9) . Reaction of [(DIPPh)₂nacnac]YbCl₂(THF)₂ with Na(OAr')(OAr'=2,6-Dimethylphenoxide) in 1:1 molar ratio in Toluene gave the binuclear organolanthanide aryloxo complex: [{(DIPPh)₂nacnac}Yb(OAr')]2(μ-Cl)₂ (10). These complexes were characterized by elemental analysis and IR spectroscopy and X-ray diffraction. These complexes were found to be the controllable initiators for ring-opening polymerization ofε-CL and L-LA .4. Polymerization kinetics ofε-CL and L-LA initiated by [{(DIPPh)₂nacnac}Yb(OAr')]2(μ-Cl)₂ (10) was measured. The conversions increase with the increasing conversions and molecular weight distributions kept narrow and unchanged.