The synthesis and characterization of aluminum alkoxide and alkyl complexes stabilized by piperazidine- bridged bis（phenolate） ligands are described. Treatment of ligand precursors Hz[ONNO]^1 {Hz[ONNO]^1= 1,4-bis（2...The synthesis and characterization of aluminum alkoxide and alkyl complexes stabilized by piperazidine- bridged bis（phenolate） ligands are described. Treatment of ligand precursors Hz[ONNO]^1 {Hz[ONNO]^1= 1,4-bis（2-hydroxy-3-tert-butyl-5-methylbenzyl）piperazidine} and Hz[ONNO]2 {H2[ONNO]2=1,4-bis（2-hydroxy3,5-di-tert-butylbenzyl）piperazidine} with A1Et2（OCH2Ph） and A1Etz（OPr-i）, which were generated in situ by the reactions of AIEt3 with equivalent of the corresponding alcohols, in a 1： 1 molar ratio in THF gave the corresponding aluminum alkoxide complexes [ONNO]IAI（OCH2Ph） （1） and [ONNO]2Al（OPr-i） （2）, respectively. The reaction of H2[ONNO]^1 with A1Etz（OCHzPh） in a 1 ： 2 molar ratio in THF afforded a mixture of monometallic aluminum ethyl complex [ONNO] 1A1Et （3） and complex 1, which can be isolated by stepwise crystallization. Similarly, Hz[ONNO]2 reacted with A1Etz（OPr-0 in a 1： 2 molar ratio in THF to give a mixture of aluminum ethyl complex [ONNO]2AlEt （4） and complex 2. Complexes 1 and 2 were also available via treatment of complexes 3 and 4 with 1 equiv, of benzyl alcohol and isopropyl alcohol, respectively. All of these complexes were fully characterized including X-ray structural determination. It was found that complexes 1 to 4 can initiate the ring-opening polymerization of e-caprolactone, and complexes 1 and 2 showed higher catalytic activity in comparison with com- plexes 3 and 4.展开更多
A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthe...A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.展开更多
A series of neutral bimetallic lanthanide aryloxides p-C6H4[OLnL(THF)n]2 [Ln = Y(1), Yb(2), Sm(3)(n = 1) and La(4)(n = 2), L = Me2NCH2CH2N{CH2-(2-O–C6H2–tBu2-3,5)}2] and alkoxides p-C6H4CH2[OLnL(THF)]2 [Ln = Y(5), Y...A series of neutral bimetallic lanthanide aryloxides p-C6H4[OLnL(THF)n]2 [Ln = Y(1), Yb(2), Sm(3)(n = 1) and La(4)(n = 2), L = Me2NCH2CH2N{CH2-(2-O–C6H2–tBu2-3,5)}2] and alkoxides p-C6H4CH2[OLnL(THF)]2 [Ln = Y(5), Yb(6)] supported by an amine-bridged bis(phenolate) ligand have been synthesized through one-pot reactions of Ln(C5H5)3(THF), LH2 with p-benzenediol and 1,4-benzenedimethanol, respectively. All complexes have been fully characterized by elemental analyses, single-crystal X-ray diffraction analysis, and IR and multi-nuclear NMR spectroscopy(in the cases of 1, 4 and 5). Study of their catalytic behavior revealed that, in general, all complexes are efficient initiators for the polymerization of rac-lactide(LA) and rac-β-butyrolactone(BBL), except for 3 and 4 in the case of BBL. The influence imposed by lanthanides of different ionic radii and initiating groups of different structures on the activity, controllability, and stereoselectivity of polymerization were systematically studied and compared. Highly heterotactic PLA(Pr up to 0.99) and syndiotactic PHB(Pr ≈ 0.81) with high molecular weight and narrow polydispersity formed and were automatically capped with hydroxyl functionality at both ends.展开更多
文摘The synthesis and characterization of aluminum alkoxide and alkyl complexes stabilized by piperazidine- bridged bis（phenolate） ligands are described. Treatment of ligand precursors Hz[ONNO]^1 {Hz[ONNO]^1= 1,4-bis（2-hydroxy-3-tert-butyl-5-methylbenzyl）piperazidine} and Hz[ONNO]2 {H2[ONNO]2=1,4-bis（2-hydroxy3,5-di-tert-butylbenzyl）piperazidine} with A1Et2（OCH2Ph） and A1Etz（OPr-i）, which were generated in situ by the reactions of AIEt3 with equivalent of the corresponding alcohols, in a 1： 1 molar ratio in THF gave the corresponding aluminum alkoxide complexes [ONNO]IAI（OCH2Ph） （1） and [ONNO]2Al（OPr-i） （2）, respectively. The reaction of H2[ONNO]^1 with A1Etz（OCHzPh） in a 1 ： 2 molar ratio in THF afforded a mixture of monometallic aluminum ethyl complex [ONNO] 1A1Et （3） and complex 1, which can be isolated by stepwise crystallization. Similarly, Hz[ONNO]2 reacted with A1Etz（OPr-0 in a 1： 2 molar ratio in THF to give a mixture of aluminum ethyl complex [ONNO]2AlEt （4） and complex 2. Complexes 1 and 2 were also available via treatment of complexes 3 and 4 with 1 equiv, of benzyl alcohol and isopropyl alcohol, respectively. All of these complexes were fully characterized including X-ray structural determination. It was found that complexes 1 to 4 can initiate the ring-opening polymerization of e-caprolactone, and complexes 1 and 2 showed higher catalytic activity in comparison with com- plexes 3 and 4.
基金supported by the National Natural Science Foundation of China(21132002,21372172,21402138)the Major Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(14KJA150007)the Qing Lan Project
文摘A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.
基金financial supported by the National Natural Science Foundation of China (20972108, 21174095, 21132002)a project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the Qing Lan Project is gratefully acknowledged
文摘A series of neutral bimetallic lanthanide aryloxides p-C6H4[OLnL(THF)n]2 [Ln = Y(1), Yb(2), Sm(3)(n = 1) and La(4)(n = 2), L = Me2NCH2CH2N{CH2-(2-O–C6H2–tBu2-3,5)}2] and alkoxides p-C6H4CH2[OLnL(THF)]2 [Ln = Y(5), Yb(6)] supported by an amine-bridged bis(phenolate) ligand have been synthesized through one-pot reactions of Ln(C5H5)3(THF), LH2 with p-benzenediol and 1,4-benzenedimethanol, respectively. All complexes have been fully characterized by elemental analyses, single-crystal X-ray diffraction analysis, and IR and multi-nuclear NMR spectroscopy(in the cases of 1, 4 and 5). Study of their catalytic behavior revealed that, in general, all complexes are efficient initiators for the polymerization of rac-lactide(LA) and rac-β-butyrolactone(BBL), except for 3 and 4 in the case of BBL. The influence imposed by lanthanides of different ionic radii and initiating groups of different structures on the activity, controllability, and stereoselectivity of polymerization were systematically studied and compared. Highly heterotactic PLA(Pr up to 0.99) and syndiotactic PHB(Pr ≈ 0.81) with high molecular weight and narrow polydispersity formed and were automatically capped with hydroxyl functionality at both ends.
