γ-脒基二阴离子β-二酮亚胺基金属酰胺和三阴离子β-二酮亚胺基 Na/Sm 杂双金属配合物的合成及其在 L-丙交酯聚合反应中的活性。

Synthesis of γ-amidine-functionalized dianionic β-diketiminato lanthanide amides and trianionic β-diketiminato Na/Sm heterobimetallic complexes and their reactivity in polymerization of L-lactide.

机构信息

Key Laboratory of Organic Synthesis of Jiangsu Province, Department of Chemistry and Chemical Engineering, Dushu Lake Campus, Soochow University, Suzhou 215123, People's Republic of China.

出版信息

Dalton Trans. 2014 Apr 14;43(14):5586-94. doi: 10.1039/c3dt52706a.

DOI:10.1039/c3dt52706a

PMID:24549149

Abstract

The readily accessible dianionic β-diketiminato lanthanide amido complexes LnLN(SiMe3)2(THF) (L = {(2,6-(i)Pr2C6H3)NC(CH2)CHC(CH3)N(2,6-(i)Pr2C6H3)}(2-)) show an unprecedented reactivity toward carbodiimides. The reaction with N,N'-dicyclohexylcarbodiimide (DCC) led via [4 + 2] cycloaddition to γ-amidine-functionalized dianionic β-diketiminato lanthanide amido complexes, LnL(1)N(SiMe3)2 (L(1) = {[(NHC6H11)(NC6H11)C]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(2-), Ln = Sm(1), Yb(2), Y(3), Gd(4)). Conversion of a mixture of SmLN(SiMe3)2(THF) and NaN(SiMe3)2 with carbodiimide furnished the heterobimetallic complexes of Sm/Na with a novel amidinate-functionalized trianionic β-diketiminate ligand, Na(DME)2[SmN(SiMe3)2] (L(2) = {[C(N(i)Pr)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-), DME = dimethoxyethane) (5) for N,N'-diisopropylcarbodiimide (DIC) and Na(DME)3 SmL(3)N(SiMe3)2 (L(3) = {[C(NCy)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-)) (6) for DCC. Molecular structures of complexes 1-6 were determined by an X-ray single crystal structure analysis. Complexes 1-4 were found to be highly active initiators of the ring-opening polymerization (ROP) of L-lactide (L-LA). The activity depended on the central metal with the increasing sequence of Yb < Y < Gd < Sm. Notably, the binary 1/BnOH (benzyl alcohol) system exhibited an "immortal" nature and proved able to convert 2000 equivalents of L-LA with up to 100 equivalents of BnOH per initiator. All the polylactides (PLAs) obtained showed monomodal, narrow molar mass distributions (M(w)/M(n) = 1.08-1.13) with the M(n) (average number molar mass) decreasing with increasing amount of BnOH proportionally.

摘要

易于接近的二阴离子β-二酮亚胺镧系元素酰胺配合物 LnLN(SiMe3)2(THF)（L = {(2,6-(i)Pr2C6H3)NC(CH2)CHC(CH3)N(2,6-(i)Pr2C6H3)}(2-)) 对碳二亚胺表现出前所未有的反应性。与 N,N'-二环己基碳二亚胺 (DCC) 的反应通过 [4 + 2] 环加成反应生成 γ-脒基官能化的二阴离子β-二酮亚胺镧系元素酰胺配合物 LnL(1)N(SiMe3)2（L(1) = {[(NHC6H11)(NC6H11)C]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(2-), Ln = Sm(1), Yb(2), Y(3), Gd(4)）。将 SmLN(SiMe3)2(THF)和 NaN(SiMe3)2 的混合物与碳二亚胺转化为具有新型酰胺基官能化三阴离子β-二酮亚胺配体的 Sm/Na 异双金属配合物，Na(DME)2[SmN(SiMe3)2]（L(2) = {[C(N(i)Pr)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-), DME = 二甲氧基乙烷）（5）对于 N,N'-二异丙基碳二亚胺（DIC）和 Na(DME)3 SmL(3)N(SiMe3)2（L(3) = {[C(NCy)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-))（6）对于 DCC。通过 X 射线单晶结构分析确定了配合物 1-6 的分子结构。发现配合物 1-4 是 L-丙交酯（L-LA）开环聚合（ROP）的高活性引发剂。活性取决于中心金属，其顺序为 Yb < Y < Gd < Sm。值得注意的是，二元 1/BnOH（苄醇）体系具有“不朽”的性质，并证明能够在每个引发剂上使用多达 100 当量的 BnOH 转化 2000 当量的 L-LA。获得的所有聚乳酸（PLA）均表现出单峰、窄摩尔质量分布（M(w)/M(n) = 1.08-1.13），随着 BnOH 比例的增加，数均摩尔质量（平均摩尔质量）逐渐减小。