Halide Abstraction Competes with Oxidative Addition in the Reactions of Aryl Halides with [Ni(PMe(n) Ph((3-n)) )(4) ].
Halide Abstraction Competes with Oxidative Addition in the Reactions of Aryl Halides with [Ni(PMe(n) Ph((3-n)) )(4) ].
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DOI：
10.1002/chem.201702331
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发表时间：
2017-11-27
期刊：
影响因子：
--
通讯作者：
Maseras F
中科院分区：
文献类型：
--
作者：
Funes-Ardoiz I;Nelson DJ;Maseras F
密度泛函理论（DFT）计算已被用于研究芳基卤化物与[Ni（PMenPh（3−n））4]型络合物的氧化加成，揭示了开壳层单线态过渡态对卤化物提取的关键作用。NiI与NiII的形成通过三种不同途径的研究得到了合理化：（i）[Ni（PMenPh（3−n））3]通过开壳层单重态过渡态的卤化物提取;（ii）[Ni（PMenPh（3−n））3]的SN 2型氧化加成，随后膦解离;以及（iii）[Ni（PMenPh（3−n））2]的氧化加成。 对于[Ni（PMe 3）4]，PhCl，和PhI之间的整体反应，微动力学模型被用来表明，我们的结果是一致的实验观察到的比例NiI和NiII时，使用的PEt 3复合物。重要的是，[Ni（PMenPh（3−n））2]配合物通常在氧化加成反应中几乎没有作用，因为它们的能量相对较高。因此，[Ni（PR 3）4]配合物在催化中的行为可能与基于双膦配体的那些有很大不同，其中两个配位Ni 0配合物是进行氧化加成的关键物种。
Density functional theory (DFT) calculations have been used to study the oxidative addition of aryl halides to complexes of the type [Ni(PMenPh(3−n))4], revealing the crucial role of an open‐shell singlet transition state for halide abstraction. The formation of NiI versus NiII has been rationalised through the study of three different pathways: (i) halide abstraction by [Ni(PMenPh(3−n))3], via an open‐shell singlet transition state; (ii) SN2‐type oxidative addition to [Ni(PMenPh(3−n))3], followed by phosphine dissociation; and (iii) oxidative addition to [Ni(PMenPh(3−n))2]. For the overall reaction between [Ni(PMe3)4], PhCl, and PhI, a microkinetic model was used to show that our results are consistent with the experimentally observed ratios of NiI and NiII when the PEt3 complex is used. Importantly, [Ni(PMenPh(3−n))2] complexes often have little, if any, role in oxidative addition reactions because they are relatively high in energy. The behaviour of [Ni(PR3)4] complexes in catalysis is therefore likely to differ considerably from those based on diphosphine ligands in which two coordinate Ni0 complexes are the key species undergoing oxidative addition.
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