Synthesis And Characterization Of Organolanthanide Complexes Supported By β-ketoiminato Ligands And Their Catalytic Behaviors

Twelve organolanthanide complexes supported byβ-ketoiminato ligands were first synthesized and well characterized. Further X-ray diffraction revealed structural features of 11 complexes. The catalytic behaviors ofβ-ketoiminato lanthanide aryloxide for ring-open polymerization ofε-caprolactone and L-lactide as well as amidation of benzaldehyde with amines were tested.1. Treatments of theβ-ketoiminate ligand C6H5NHC(CH3)CHCO(CH3) (LH) with 0.5 equiv. of (ArO)3Ln·THF (ArOH = 2,6-di-tert-butyl-4-methylphenol) afforded two neutral mononuclear lanthanide complexes bearing twoβ-ketoiminato ligands and one aryloxide: LnL2(OAr)·DME (Ln = Nd (1), Sm (2)). Both of them were characterized by elemental analysis, IR spectroscopy and X-ray diffraction determination for complex 2. In complexes 2, the lanthanide metal is coordinated by twoβ-ketoiminato ligands, one aryloxide and one DME molecule in a distorted pentagonal bipyramid geometry.2. Treatments of theβ-ketoiminate ligand LH with 0.5 equiv. of Na(THF)6Ln(OAr)4 afforded three anionic lanthanides bearing twoβ-ketoiminato ligands and two aryloxides: Na(DME)3LnL2(OAr)2 (Ln = La (3), Nd (4), Sm (5)). All of the complexes were characterized by elemental analysis, IR spectroscopy, and X-ray diffraction determination. Complex 3 was also characterized by 1H NMR and 13C NMR spectroscopy. In these complexes, each lanthanide metal is coordinated by twoβ-ketoiminato ligands, two aryloxides in a distorted octahedron coordination geometry.3. Treatments of theβ-ketoiminate ligand LH with 0.5 equiv. of the mixture of (ArO)3Ln·THF and ArONa in 1:1 molar ratio afforded two anionic lanthanides bearing twoβ-ketoiminato ligands and two aryloxides: Na(DME)3LnL2(OAr)2 (Ln = Y (6), Yb (7)). Both of them were characterized by elemental analysis, IR spectroscopy, and X-ray diffraction determination. In complexes 6 and 7, each lanthanide metal is coordinated by twoβ-ketoiminato ligands, two aryloxides in a distorted octahedron coordination geometry.4. The treatment of theβ-ketoiminate ligand LH with 0.5 equiv. of Na(THF)6La(OAr)4 afforded the anionic lanthanide bearing twoβ-ketoiminato ligands and one aryloxide: LaL22,6-Me(OAr)·L2,6-MeNa (8). The complex was characterized by elemental analysis, IR spectroscopy, and X-ray diffraction determination. In complex 8, the lanthanum metal is coordinated by twoβ-ketoiminato ligands, one aryloxides and a neutralβ-ketoiminate molecule in a distorted octahedron coordination geometry.5. Treatments of theβ-ketoiminate ligand LH with 0.5 equiv. of the solution of Na(THF)6Ln(OAr)4 afforded the anionic lanthanide which bearing twoβ-ketoiminato ligands and one aryloxide: LnL22,6-Me(OAr)·L2,6-MeH (Ln = Nd (9), Sm (10)). Both of them were characterized by elemental analysis, IR spectroscopy, and X-Ray diffraction determination. In complexes 9 and 10, each lanthanide metal is coordinated by twoβ-ketoiminato ligands, one aryloxides and a neutralβ-ketoiminate molecule, in a distorted octahedron coordination geometry.6. The treatment of theβ-ketoiminate ligand LH with 0.5 equiv. of the solution of Na(THF)6La(OAr')4 (Ar'OH = 2,6-di-tert-butylphenol) afforded a neutral mononuclear lanthanide bearing twoβ-ketoiminato ligands and one aryloxide: LaL2(OAr')·DME (11). This complex was characterized by elemental analysis, IR spectroscopy, and X-ray diffraction determination. In complex 11, the lanthanide metal is coordinated by twoβ-ketoiminato ligands, one aryloxide and one DME molecule in a distorted pentagonal bipyramid geometry.7. The treatment of theβ-ketoiminate ligand LH with 0.5 equiv. of the solution of Na(THF)6Nd(OAr')4 afforded the neodymium complex bearing threeβ-ketoiminato ligands: (NdL3)2 (12). This complex was characterized by elemental analysis, IR spectroscopy, and X-ray diffraction determination. In complex 12, the two lanthanide metals are coordinated by threeβ-ketoiminato ligands and bridged through the oxygen atom from eachβ-ketoiminato ligands. The geometry of central metal can be best described as a distorted octahedron geometry.8. Complexes 1-5 can be used as single-component catalysts for the ring-opening polymerization ofε-CL and L-LA to give the polyesters with high number-average molecular weights and relatively narrow molecular weight distributions. 9. Complexes 3-5 can also be used as single-component catalysts for amidation reaction of aldehyde with amines with high activity.