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在稀土配位共轭双烯烃聚合反应机理的研究中,一般认为按π-烯丙基机理进行,但迄今为止尚缺乏足够的实验证据。我们曾用~1H-NMR、一维~(13)C-NMR和二维~(13)C-NMR系统地研究了(CF_3COO)_2LnCl·EtoH-(i-Bu)_2AIH-共轭双烯烃(Ln=La、Pr、Nd、Sm、Tb、Ho、Sc和Y)均相聚合体系的聚合机理,提出了η~4-共轭双烯(顺式-反式-)和η~3-烯丙基(同式-对式-)机理。但由于广烯丙基稀土配合物稳定性差,难于合成,加之聚合体系中很难直接分离出π-烯丙基稀土配合物活性体,为此,至今尚未能用模型π-烯丙基稀土配合物对上述机理进行研究。我们已合成一系列π-烯丙基稀土配合物LiLn
In the study of the mechanism of the polymerization of rare earth coordination conjugated diolefins, it is generally considered that the π-allylic mechanism is carried out, but so far there is not enough experimental evidence. We have systematically investigated the effect of (CF_3COO) _2LnCl · EtoH- (i-Bu) _2AIH-conjugated diolefin ( Ln = La, Pr, Nd, Sm, Tb, Ho, Sc and Y) were proposed. The polymerization mechanism of η 4- conjugated diolefin Propyl (same type - to - type) mechanism. However, due to the poor stability of wide-base propyl rare earth complexes, difficult synthesis, coupled with the polymerization system is difficult to separate the π-allyl rare earth complex active, therefore, has not yet used model π-allyl rare earth Complexes to study the above mechanism. We have synthesized a series of π-allyl rare earth complexes LiLn