Halide Abstraction Competes with Oxidative Addition in the Reactions of Aryl Halides with [Ni(PMePh)]
Density functional theory (DFT) calculations have been used to study the oxidative addition of aryl halides to complexes of the type [Ni(PMePh)], revealing the crucial role of an open-shell singlet transition state for halide abstraction. The formation of Ni I versus Ni II has been rationalised thro...
| Authors: | , , |
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| Format: | article |
| Publication Date: | 2017 |
| Country: | España |
| Institution: | Universitat Autònoma de Barcelona |
| Repository: | Dipòsit Digital de Documents de la UAB |
| Language: | English |
| OAI Identifier: | oai:ddd.uab.cat:186358 |
| Online Access: | https://ddd.uab.cat/record/186358 https://dx.doi.org/urn:doi:10.1002/chem.201702331 |
| Access Level: | Open access |
| Keyword: | Density functional calculations Electron transfer Homogeneous catalysis Ligand effects Nickel |
| Summary: | Density functional theory (DFT) calculations have been used to study the oxidative addition of aryl halides to complexes of the type [Ni(PMePh)], revealing the crucial role of an open-shell singlet transition state for halide abstraction. The formation of Ni I versus Ni II has been rationalised through the study of three different pathways: (i) halide abstraction by [Ni(PMePh)], via an open-shell singlet transition state; (ii) S2-type oxidative addition to [Ni(PMePh)], followed by phosphine dissociation; and (iii) oxidative addition to [Ni(PMePh)]. For the overall reaction between [Ni(PMe)], PhCl, and PhI, a microkinetic model was used to show that our results are consistent with the experimentally observed ratios of Ni I and Ni II when the PEt complex is used. Importantly, [Ni(PMePh)] complexes often have little, if any, role in oxidative addition reactions because they are relatively high in energy. The behaviour of [Ni(PR)] complexes in catalysis is therefore likely to differ considerably from those based on diphosphine ligands in which two coordinate Ni 0 complexes are the key species undergoing oxidative addition. |
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