Wang Junfeng, Yao Yingming, Zhang Yong, Shen Qi
Key Laboratory of Organic Synthesis Jiangsu Province, Chemistry and Chemical Engineering of Suzhou University, Suzhou, 215123, China.
Inorg Chem. 2009 Jan 19;48(2):744-51. doi: 10.1021/ic801189j.
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.
高产率合成了具有不同分子结构的桥联双（脒基）镱醇盐和酚盐，并通过X射线晶体结构分析进行了确证。LYbCl(THF)(2)（L = Me(3)SiNC(Ph)N(CH(2))(3)NC(Ph)NSiMe(3)）与1当量的NaOAr（ArO = 2,6 - 二异丙基苯氧基）反应，得到单核配合物LYb(OAr)DME 1，其中镱原子为七配位，周围环绕着一个螯合双（脒基）配体、一个酚氧基和一个DME（二甲氧基乙烷）分子。与1当量的NaO(i)Pr进行相同反应，得到双核配合物Yb(μ(2)-L)(2)(μ(2)-O(i)Pr)(2)Yb，即2，其具有两个等价的六配位金属中心，通过两个相连的双（脒基）和两个通过复分解反应过程中发生的配体重新分布反应形成的O(i)Pr桥连接。1和2均以可控方式引发L - 丙交酯以及ε - 己内酯（ε - CL）的开环聚合，反应活性高，M(n)与转化率之间呈线性关系以及分子量分布窄（PDI = 1.15 - 1.25）直至100%转化率表明了这一点。讨论了配合物1和2之间催化性能的差异。
