Bridged bis(amidinate) ytterbium alkoxide and phenoxide: syntheses, structures, and their high activity for controlled polymerization of L-lactide and epsilon-caprolactone.
Bridged bis(amidinate) ytterbium alkoxide and phenoxide: syntheses, structures, and their high activity for controlled polymerization of L-lactide and epsilon-caprolactone.
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DOI：
10.1021/ic801189j
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发表时间：
2009-01
影响因子：
4.6
通讯作者：
Junfeng Wang;Yingming Yao;Yong Zhang;Q. Shen
中科院分区：
文献类型：
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作者：
Junfeng Wang;Yingming Yao;Yong Zhang;Q. Shen
高产率地合成了具有不同分子结构的桥联双(酰胺)Yb醇盐和苯氧化合物，并经X-射线晶体结构分析证实。LYbCl(THF)(2)(L=Me(3)sinc(Ph)N(CH2)(3)Nc(Ph)NSiMe(3))与1当量NaOAr(ArO=2，6-二异丙基苯氧基)反应，合成了单核配合物LYB(OAr)DME1，其周围有一个螯合双(酰胺)配体、一个苯氧基和一个二甲醚(DME)分子。与1当量的NaO(I)Pr反应生成了Yb(Mu(2)-L)(2)(Mu(2)-O(I)Pr)(2)Yb，2，其中两个等价的六配位金属中心由两个连接的双酰亚胺S连接，两个O(I)Pr桥通过复分解反应中发生的配体重分配反应形成。1和2均以可控方式引发了L-丙交酯和己内酯的开环聚合，反应活性较高，M(N)与转化率呈线性关系，分子量分布较窄(Pdi=1.15~1.25)，转化率达100%。讨论了配合物1和2在催化性能上的差异。
Bridged bis(amidinate) ytterbium alkoxide and phenoxide with diverse molecular structures were synthesized in high yields and confirmed by X-ray crystal structural analysis. The reaction of LYbCl(THF)(2) (L = Me(3)SiNC(Ph)N(CH(2))(3)NC(Ph)NSiMe(3)) with 1 equiv of NaOAr (ArO = 2,6-diisopropylphenoxo) afforded the mononuclear complex LYb(OAr)DME 1 with a seven-coordinated ytterbium atom surrounded by one chelating bis(amidinate) ligand, one phenoxo group, and one DME (dimethoxyethane) molecule. The same reaction with 1 equiv of NaO(i)Pr yielded the binuclear complex Yb(mu(2)-L)(2)(mu(2)-O(i)Pr)(2)Yb, 2, with two equivalent six-coordinate metal centers connected by two linked bis(amidinate)s and two O(i)Pr bridges formed via a ligand redistribution reaction that occurred during the metathesis reaction. Both 1 and 2 initiated the ring-opening polymerization of L-lactide, as well as epsilon-caprolactone (epsilon-CL), in a controlled manner with high reactivity, as indicated by a linear relationship between M(n) and conversion and by narrow molecular weight distributions (PDI = 1.15-1.25) up to 100% conversion. The differences in catalytic performance between complexes 1 and 2 are discussed.