Synthesis Characterization Of Carbon-bridged Bis(aryloxide) Lanthanide Complexes And Studies On Their Catalytic Reactivity

A new class of ionic and neutral lanthanide complexes supported by carbon-bridgedbis(aryloxide) were synthesized and characterized. Catalytic reactivities of thesecomplexes for Diels-Alder reaction and ring-opening polymerization of e-caprolactonewere studied, respectively. The bis(aryloxide) used is2,2'-methylene-bis(6-tert-butyl-4-methylphenoxo), abbreviated as MBMP.1 . Reaction of anhydrous LnCl3 with Na2MBMP in THF in 1 :2 molar ratio afforded ioniccomplexes [(THF)nLn(MBMP)2Na(THF)2] (Ln = Nd, n=2 (1); Ln = Sm (2), Er (3), Yb(4), n=l). All of these complexes were characterized by IR, 'HNMR, elementalanalysis and X-ray diffraction. Due to their Lewis acidity, they can catalyze tieDiels-Alder reaction of cyclopentadiene with methyl acrylate with good catalyticactivity and stereoselectivity.2. Great influency of coordinate solvent upon the structures of ionic carbon-bridged biphenolato lanthanide complexes was found. Quantitive coordinate solvent-DME was added during the preparation reaction or crystallization, sodium ion in complex 1, 2 and 4 will be extracted and become free one, thus new solvated anion-cation pair complexes [(MBMP)2Ln(THF)2][Na(DME)2(THF)2] (Ln = Nd (5), Sm (6), Yb (7)) were formed. Sufficient characterization was done for complex 5-7, and crystal structure of complex 7 was determined.3. Another class of ionic complex containing a neutral aryloxo group (NaMBMP)2Sm(OAr) (ArO = 2,6-But2-4-Me-C6H2O) (8) was synthesized by the reaction of Sm(OAr)2Cl with Na2MBMP with 1:1 molar ratio in THF at room temperature. It was characterized by IR and elemental analysis. Due to loss solvent for single crystal 8, we can only get the skeleton diagram of its structure. Further study reveals that complex 8 is a highly efficient initiator for the ring-opening polymerization of e-caprolactone.4. Raction of Cp2YbCl or (ArO)2YbCl with MBMPH2 in THF in 1:1 molar ratio gave tieAbstractcomplex [(MBMPJYbOrClXTHF)^ (9). Complex 9 was characterized by IR and elemental analysis. Structure determination revealed it is a dimer. It was found mat complex 9 is inert for the ring-opening polymerization of e-caprolactone.5. Reaction of complex Ln(OAr>3 with MBMPH2 in THF in 1:1 molar ratio gave the neutral carbon-bridged biphenolato lanthanide complex (MBMP)Ln(OAr)(THF)2 (La = Sm (10), Er (11), Yb (12) ). All of them were characterized by IR, elemental analysis. Crystal structrue of complexes 10 and 12 showed they were monomeric. As the reaction precussor, single crystal structure of complex (ArO)3Er(THF) (13) was measured at the same time. Catalytic activities of complex 10 and 12 for the ring-opening polymerization of e-caprolactone were investigated. These complexes showed modest catalytic activity, and the PDIs of the polymers obtained were relatively broad.6. Reaction of CpjLn with MBMPHa in THF in 1 :1 molar ratio, isopropanol was added to the system in 1 equiv., after workup, a new kind of neutral lanthanide complexes [(MBMP)LnCw-OiPrXTHF)2]2 (Ln = La (14), Nd (15) ,Yb (16)) were gained. These complexes were characterized by IR, elemental analysis. In addition, complex 14 was also characterized by 'HNMR, X-ray diffraction of complex 15 and 16 indicated they were dimeric in solid state. Their catalytic activities for ring-opening polymerization of e-caprolactone were explored. It was found that these complexes can initiate the living polymerization of e-caprolactone, and they showed relatively high activity comparison with other lanthanide initiators reported before.