13C-NMR STUDIES ON η4-IP,η3-ALLYL RARE EARTH CO MPLEXES AND THEIR TAUTOMERIZATION IN THE POLYMERIZATION PROCESSES OF ISOPRENE BASED ON (CF3 CO2) LnCl·EtOH-(i-Bu)2AIH HOMOGENEOUS CATALYST

ZHANG Xi-tian; PEI Feng-kui; LI Xing-min; JIN Ying-tai; DING Ji-zhen; ZHANG Shui-zhen

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13C-NMR STUDIES ON η4-IP,η3-ALLYL RARE EARTH CO MPLEXES AND THEIR TAUTOMERIZATION IN THE POLYMERIZATION PROCESSES OF ISOPRENE BASED ON (CF3 CO2) LnCl·EtOH-(i-Bu)2AIH HOMOGENEOUS CATALYST

Research Article | 更新时间：2021-03-19

- 13C-NMR STUDIES ON η4-IP,η3-ALLYL RARE EARTH CO MPLEXES AND THEIR TAUTOMERIZATION IN THE POLYMERIZATION PROCESSES OF ISOPRENE BASED ON (CF3 CO2) LnCl·EtOH-(i-Bu)2AIH HOMOGENEOUS CATALYST
- Acta Polymerica Sinica Issue 4, Pages: 391-398(1990)
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- Published：20 August 1990，
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ZHANG Xi-tian, PEI Feng-kui, LI Xing-min, JIN Ying-tai, DING Ji-zhen, ZHANG Shui-zhen. 13C-NMR STUDIES ON η4-IP,η3-ALLYL RARE EARTH CO MPLEXES AND THEIR TAUTOMERIZATION IN THE POLYMERIZATION PROCESSES OF ISOPRENE BASED ON (CF3 CO2) LnCl·EtOH-(i-Bu)2AIH HOMOGENEOUS CATALYST. [J]. Acta Polymerica Sinica (4):391-398(1990)
DOI：

ZHANG Xi-tian, PEI Feng-kui, LI Xing-min, JIN Ying-tai, DING Ji-zhen, ZHANG Shui-zhen. 13C-NMR STUDIES ON η4-IP,η3-ALLYL RARE EARTH CO MPLEXES AND THEIR TAUTOMERIZATION IN THE POLYMERIZATION PROCESSES OF ISOPRENE BASED ON (CF3 CO2) LnCl·EtOH-(i-Bu)2AIH HOMOGENEOUS CATALYST. [J]. Acta Polymerica Sinica (4):391-398(1990) DOI：

摘要

本文用13C-NMR研究了异戊二烯(IP)在均相催化剂(CF3CO2)2LnCl·EtOH—(i-Bu)AlH—o-C6D4Cl2作用下的聚合过程。单体首先被活化同稀土配位生成η4-IP稀土配合物(反式和顺式)

然后η4-IP的C-3和C-4插入Ln-H键生成η3-烯丙基稀土配合物——η3-(2-甲基)丁烯基稀土配合物(同式和对式)。二维13C-NMR交换谱表明η4-IP和0η3-烯丙基的每对异构体在常温下分别进行慢交换反应(互变异构)

这一过程使插入反应在常温下得以进行。

Abstract

The polymerization processes of isoprene (IP) based on (CF3CO2)2LnCl·EtOH一(i-Bu)2AlH homogeneous catalysts were traced out by 13C-NMR. First，IP coordina-ted to rare earth to become

n4-IP rare earth complexes trans and cis)．Then C-3 and C-4 of

n4-IP inserted into Ln-H bond to form n3-allyl rare earth complexes (syn and anti)．13C chemical shifts and 1JcH coupling constants of n4-IP indicated that C一1 and C-2 of n4-IP coordinated to rare earth with π coordination bond，while the double bond between C-3 and C-4 transformed to σ bond to form a metal cyclopropane structure with rare earth，i.e. a activated structure．2D 13C-NMR exchange spectra showed that the slow exchange (tautomcrism) reaction between every pair of n4-IP and

n3-allyl isomers could take place at ambient temperature．These reactions underwent the processes of bond breaking and reformi-ng

which enable insert reaction to take place at room temperature．The suggested polymerization mechanism is IP—n4-trans—IP→n4-cis-IP一n3-syn-allyl→n3一anti-allyl—trans一1，4一IP／cis—1，4一IP(C-1 insert) or 3

4-IP(C-3 insert)unit．

关键词

13C-NMRη4-IP稀土配合物η3-烯丙基稀土配合物互变异构

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