| A series of anionic lanthanide complexes supported by carbon-bridged bis(phenolate)ligands were synthesized and structurally characterized, and their catalytic activity for the polymerization of e-caprolactone was tested. At the same time, the amido and aryloxo lanthanide complexes based onβ-diketiminate were synthesized, it was found that the corresponding lanthanide diamido complexes were efficient initiators for the polymerization ofε-caprolactone and lactide.1. Reactions of anhydrous LnCl3 with Li2MBMP in a 1:2 molar ratio in THF afforded the anionic lanthanide complexes[(THF)2Sm(MBMP)2][Li(THF)4](1) and[(THF)Yb(MBMP)2Li(THF)2](2), which were characterized by elemental analysis and IR spectra, X-ray single crystal analysis revealed 1 was an"ate" complex with a coordination number of 6 for Sm atom, while 2 was a bimetallic complex and in which Yb and Li were linked by two aryloxo groups, the coordination number of Yb was 5.2. Reaction of anhydrous LaCl3 with Na2MBMP in a 1:2 molar ratio in THF produced the anionic lanthanum complex[(THF)2La(MBMP)2Na(THF)2](3), 3 was characterized by elemental analysis, ER spectrum and X-ray single crystal diffraction.3. Reactions of anhydrous LnCl3 with K2MBMP in a 1:2 molar ratio in THF obtained the anionic lanthanide complexes[[La(THF)2]2(MBMP)4K}K(THF)6(4),[Nd2(MBMP)4K2(THF)2](5),[(THF)2Sm(MBMP)2K(THF)2](6), and[(THF)2Yb(MBMP)2K(THF)3](7). All of the complexes were characterized by elemental analysis and IR spectra. Single crystal structure determination showed 4 was an"ate" complex and in the anionic segment of which two anion cores were linked by the K cation. While complex 5 demonstrated a binuclear structure in the solid state and in which two Nd atoms were linked by two bis(aryloxide) ligands, two K cations were located in two outer bis(phenolate) ligands. Complexes 6 and 7 were isostructural. Their structures are different from that of complexes 4 and 5, but are same as that of the corresponding anionic complexes containing sodium cation. 4. Complexes 1-7 can be used as single component catalysts to initiate the ring-opening polymerization ofε-caprolactone with moderate activity. In the presence of 1 equivalent of isopropanol, complexes 1-7 can catalyze the same polymerization in a controlled manner.5. Reaction of[{(2,6-Me2C6H3)NC(Me)}2CH]SmCl2(THF)2 with LiNPh2 in a 1:2 molar ratio in THF, after workup, afforded the diphenylamido complex[{(2,6-Me2C6H3)NC(Me)}2CH]Sm(NPh2)2(THF)(8) in high yield, which was characterization by elemental analysis and IR spectrum. Complex 8 can initiate the polymerization ofε-caprolactone and L-Lactide in very high activity. Compared with 8, the known complex[{(2,6-iPr2C6H3)NC(Me)}2CH]Yb(NPh2)2 showed lower activity.6. An unexpected complex[{(2,6-iPr2C6H3)NC(Me)}2CH]Yb(THF)(μ-Cl)3Yb(O-C6H3-2,6-Me2)[{(2,6-iPr2C6H3)N C(Me)}2CH](9) was synthesized by the reaction of[{(2,6-iPr2C6H3)NC(Me)}2CH]YbCl2(THF)2 with sodium 2,6-di-methylphenoxide in THF in a 1:1 molar ratio, which was characterized by elemental analysis and IR spectrum. Crystal structure determination of 9 revealed that it has a binuclear structure, in which two Yb atoms were linked by a trichloro bridge, the aryloxo group was coordinated to one of the Yb atoms. |
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