Synthesis, Characterization Of Amine Bis(Phenolate) Lanthanide Complexes And Their Catalytic Behavior

Twenty-one amine bis(phenolate) lanthanide complexes were synthesized and well characterized. The molecular structures of 16 complexes were further determined by X-ray diffiraction analysis. The catalytic behaviors of some amine bis(phenolate) lanthanide complexes were tested. 1. Reaction of anhydrous LnCl3 and sodium amine bis(phenolate) L1Na2 or L2Na2(L1 = Me₂NCH₂CH₂N{CH₂-(2-O-C₆H₂-But₂-3,5)}₂, L² = Me₂NCH₂CH₂N{CH₂-(2-O-C₆H₂-Me-5-But-3)}2) in 1:1 molar ratio gave complexes L1LnCl(THF) (Ln = Yb (1), Er (2)) and L²LnCl(THF) (Ln = Yb (3), Er (4)). Complexes 1-4 were characterized by IR and elemental analysis. X-ray crystal structures of complexes 1-3 were determined. In these complexes, each lanthanide metal atom is six-coordinated by two nitrogen atoms and two oxygen atoms from the amine bis(phenolate) ligand, one chlorine atom and one oxygen atom from THF molecule to form a distorted octahedron coordination geometry. 2. Reaction of (t^BuCp)₂NdCl(THF)₂ with amine bis(phenolate) ligand L¹H₂ in a 1:1 molar ratio afforded the complex L¹NdCl(DME) (5). Complex 5 was characterized by IR, elemental analysis and X-ray diffraction structure analysis. X-ray crystal structures of complex 5 revealed that the neodymium atom is seven-coordinated by two nitrogen atoms and two oxygen atoms from the amine bis(phenolate) ligand, one chlorine atom and two oxygen atoms of DME molecule in trigonal prismatic coordination geometry. 3. Reaction of complex 1-5 with Ph2NLi in a 1:1 molar ratio gave the amine bis(phenolate) lanthanide amides L¹LnNPh₂(THF) (Ln = Yb (6), Er (7)), L¹NdNPh₂(DME) (8) and L²LnNPh₂(THF) (Ln = Yb (9), Er (10)). Complexes 6-10 were characterized by IR and elemental analysis. X-ray crystal structures of complexes 6 and 7 were determined, and the coordination geometry around central metal is similarto those of complexes 1-3. 4. Treatments of L¹LnCl(THF) with 1 equiv. of MeLi at ice-salt bath afforded the lanthanide methyl complexes L¹LnMe(THF) (Ln = Yb (12), Er (13)) in moderate yield. Both complexes were characterized by IR and elemental analysis. X-ray crystal structure of complex 12 revealed that the coordination geometry of ytterbium atom is a distorted octahedron. 5. Reaction of amine bis(phenolate) ligand L1H2 with Cp3Ln(THF)n in a 1:1 molar ratio gave complexes L1LnCp(THF) (Ln = Yb (15), Er (16)). Complexes 15 and 16 were characterized by IR, elemental analysis and X-ray crystal structure determination. Complex 15 and 16 display a distorted octahedral coordination geometry. Further reactions of complexes 15 and 16 with 1 eqviu. of iPrOH are unsuccessful. 6. Reaction of anhydrous LnCl3 with L1Na2 in THF in 1:2 molar ratio afforded ionic complexes (L1)2YbM(THF)n (M = Li, n = 2 (18); M = Na, n = 2 (19); M = K, n = 3 (20)). All of these complexes were characterized by IR, 1HNMR, elemental analysis and X-ray diffraction structure determination. 7. The effect of coordinate solvent upon the structure of ionic amine bis(phenolate) lanthanide complex was studied. It was found that three THF molecules bounded to the potassium atom in complex 20 were insteaded by two DME molecules, producing the complex (L1)2YbK(DME)2 (21) when quantitive coordinate solvent DME was added to the toluene solution of (L1)2YbK(THF)3. The coordination geometry of ytterbium and potassium in complex 21 are both distorted octahedron. 8. It was found that complexes 6, 7 and 12 showed extremely high activity for the ring-opening polymerization of ε-caprolactone.