Evidence for Ligand-Dependent Mechanistic Changes in Nickel-Catalyzed Chain-Growth Polymerizations
Evidence for Ligand-Dependent Mechanistic Changes in Nickel-Catalyzed Chain-Growth Polymerizations
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DOI：
10.1021/ma101565u
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发表时间：
2010-10-12
期刊：
影响因子：
5.5
通讯作者：
McNeil, Anne J.
中科院分区：
文献类型：
--
作者：
Lanni, Erica L.;McNeil, Anne J.
研究了Ni（dppp）Cl-2催化4-溴-2，5-双（己氧基）苯基氯化镁和5-溴-4-己基噻吩-2-基氯化镁的链增长聚合反应机理。结合速率和光谱研究表明，transmetalation是两种单体的催化循环的速率决定步骤。P-31 NMR光谱研究表明，镍（II）芳基卤化物和镍（II）噻吩基卤化物是催化剂的静止状态。此外，发现LiCl改变芳烃聚合速率。这些结果是不同于先前获得的替代催化剂（Ni（dppe）Cl-2），并表明，配体具有很强的机械影响的聚合。
The mechanisms for Ni(dppp)Cl-2-catalyzed chain-growth polymerization of 4-bromo-2.5-bis(hexyloxy)phenylmagnesium chloride and 5-bromo-4-hexylthiophen-2-ylmagnesium chloride were investigated. A combination of rate and spectroscopic studies revealed that transmetalation is the rate-determining step of the catalytic cycle for both monomers. P-31 NM R spectroscopic studies revealed that a Ni(II) aryl halide and a Ni(II) thienyl halide are the catalyst resting states. In addition, LiCI was found to alter the arene polymerization rates. These results are different than those previously obtained with an alternative catalyst (Ni(dppe)Cl-2) and suggest that the ligand has a strong mechanistic influence on the polymerization.