Mechanistic Studies on Ni(dppe)Cl2-Catalyzed Chain-Growth Polymerizations: Evidence for Rate-Determining Reductive Elimination
Mechanistic Studies on Ni(dppe)Cl2-Catalyzed Chain-Growth Polymerizations: Evidence for Rate-Determining Reductive Elimination
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DOI：
10.1021/ja904197q
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发表时间：
2009-11-18
影响因子：
15
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(dppe) 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-基氯化镁的链式聚合机理。利用红外光谱和气相色谱的速率研究表明，这两种聚合都表现出一阶依赖于催化剂浓度，而零阶依赖于单体浓度。反应性有机金属中间体的P-31 NMR研究表明静息态为不对称的ni - ii -联芳基和ni - ii -噻吩配合物。结合起来，数据暗示还原消除作为两个单体的速率决定步骤。此外，还发现LiCl对芳烃聚合的速率决定步骤和分子量分布没有影响。
The mechanisms for Ni(dppe)Cl-2-catalyzod chain-growth polymerization of 4-bromo-2,5-bis(hexyloxy)phenyl magnesium chloride and 5-bromo-4-hexylthiophen-2-ylmagnesium chloride were investigated. Rate studies utilizing IR spectroscopy and gas chromatography revealed that both polymerizations exhibit a first-order dependence on the catalyst concentration but a zeroth-order dependence on the monomer concentration. P-31 NMR spectroscopic studies of the reactive organometallic intermediates suggest that the resting states are unsymmetrical Ni-II-biaryl and Ni-II-bithiophene complexes. In combination, the data implicate reductive elimination as the rate-determining step for both monomers. Additionally, LiCl was found to have no effect on the rate-determining step or molecular weight distribution in the arene polymerization.