Light‐Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII‐Aryl Complex

Yang, Liu; Lu, Huan‐Huan; Lai, Chu‐Hui; Li, Gang; Zhang, Wei; Cao, Rui; Liu, Fengyi; Wang, Chao; Xiao, Jianliang; Duan, Xue

doi:10.1002/anie.202003359

Cited by 105 publications

(117 citation statements)

References 68 publications

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“…While it is unclear whether these species initiate a subsequent Ni(I)/Ni(III) catalytic cycle, this represents an intriguing means to photochemically generate reduced Ni species and organic radicals for ground state thermal catalysis. 18,20 Overall, more detailed experimental and theoretical descriptions of the ground state bonding and excited state relaxation processes in Ni-bpy complexes (and other Ni heteroaromatic complexes 24 ) are critical for developing synthetic applications. Here we describe a new electronic structural framework to interpret experimental data on Ni(II)-bpy complexes of relevance to photoredox catalysis.…”

Section: Introductionmentioning

confidence: 99%

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

et al. 2020

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Multireference electronic structure calculations consistent with known experimental data have elucidated a novel mechanism for photo-triggered Ni(II)-C homolytic bond dissociation in Ni 2,2'bipyridine (bpy) photoredox catalysts. Previously, a thermally assisted dissociation from the lowest energy triplet ligand field excited state was proposed and supported by density functional theory (DFT) calculations that reveal a barrier of ~30 kcal mol-1. In contrast, multireference ab initio calculations suggest this process is disfavored, with barrier heights of ~70 kcal mol-1 , and highlight important ligand noninnocent contributions to excited state relaxation and bond dissociation processes that are not captured with DFT. In the multireference description, phototriggered Ni(II)-C homolytic bond dissociation occurs via initial population of a singlet Ni(II)-tobpy metal-to-ligand charge transfer (1 MLCT) excited state followed by intersystem crossing and aryl-to-Ni(III) charge transfer, overall a formal two-electron transfer process driven by a single photon. This results in repulsive triplet excited states from which spontaneous homolytic bond dissociation can occur, effectively competing with relaxation to the lowest energy, nondissociative triplet Ni(II) ligand field excited state. These findings guide important electronic structure considerations for the experimental and computational elucidation of the mechanisms of ground and excited state cross-coupling catalysis mediated by Ni heteroaromatic complexes.

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Section: Introductionmentioning

confidence: 99%

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

et al. 2020

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“…Tr ansient absorption (TA) spectroscopy showed that one of the two absorptions by bpyC À disappeared, meaning that the MLCT state evolved to ad ifferent excited state.T he relatively constant lifetimes of different substituted Ni II excited states were also inconsistent with the trend in the MLCT states.T he fact that the Lewis basicity of the solvent had as mall effect on the excited-state lifetimes implies that the initially generated MLCT state may evolve into al ong-lived tetrahedral 3 Very recently,X ue and co-workers reported photoinduced nickel-catalyzed CÀOc ouplings using aN i II -aryl complex as the catalyst without any additional photosensitizer (Scheme 14 B). [38] Ther eactions were performed with as oluble amine as the base under irradiation by longwave UV (390-395 nm) at an elevated temperature of 80 8 8C. The mechanism was similar to that proposed by Doyle,i nw hich active Ni I species were generated via the light-promoted homolysis of the Ni II -aryl complex through al ong-lived 3 d-d excited state.T he signals at g k = 2.25 and g ?…”

Section: Photoinduced Nickel-catalyzed Reactionsmentioning

confidence: 68%

Nickel‐Catalyzed C‐Heteroatom Cross‐Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination

et al. 2021

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The formation of C‐heteroatom bonds represents an important type of bond‐forming reaction in organic synthesis and often provides a fast and efficient access to privileged structures found in pharmaceuticals, agrochemical and materials. In contrast to conventional Pd‐ or Cu‐catalyzed C‐heteroatom cross‐couplings under high‐temperature conditions, recent advances in homo‐ and heterogeneous Ni‐catalyzed C‐heteroatom formations under mild conditions are particularly attractive from the standpoint of sustainability and practicability. The generation of NiIII and excited NiII intermediates facilitate the reductive elimination step to achieve mild cross‐couplings. This review provides an overview of the state‐of‐the‐art approaches for mild C‐heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel catalysis; electro and nickel dual catalysis; heterogeneous photoredox and nickel dual catalysis involving graphitic carbon nitride (mpg‐CN), metal organic frameworks (MOFs) or semiconductor quantum dots (QDs); as well as more conventional zinc and nickel dual catalyzed reactions.

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“…The yield of cross-coupled product obtained from direct excitation of 1 is incident light dependent; high yields are only observed with UV light (390-395 nm or ~70 kcal mol -1 ), 20 corresponding to excitation into the higher energy manifold of MLCT states (Figure 4). Of Thus, an alternative relaxation pathway and mechanism may exist for photosensitized crosscoupling.…”

Section: Resultsmentioning

confidence: 99%

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

Cagan

Stroscio

Cusumano

et al. 2020

Preprint

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Multireference electronic structure calculations consistent with known experimental data have elucidated a novel mechanism for photo-triggered Ni(II)–C homolytic bond dissociation in Ni 2,2’-bipyridine (bpy) photoredox catalysts. Previously, a thermally assisted dissociation from the lowest energy triplet ligand field excited state was proposed and supported by density functional theory (DFT) calculations that reveal a barrier of ~30 kcal mol-1. In contrast, multireference ab initio calculations suggest this process is disfavored, with barrier heights of ~70 kcal mol-1, and highlight important ligand noninnocent contributions to excited state relaxation and bond dissociation processes that are not captured with DFT. In the multireference description, photo-triggered Ni(II)–C homolytic bond dissociation occurs via initial population of a singlet Ni(II)-to-bpy metal-to-ligand charge transfer (1MLCT) excited state followed by intersystem crossing and aryl-to-Ni(III) charge transfer, overall a formal two-electron transfer process driven by a single photon. This results in repulsive triplet excited states from which spontaneous homolytic bond dissociation can occur, effectively competing with relaxation to the lowest energy, nondissociative triplet Ni(II) ligand field excited state. These findings guide important electronic structure considerations for the experimental and computational elucidation of the mechanisms of ground and excited state cross-coupling catalysis mediated by Ni heteroaromatic complexes.

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Light‐Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a Ni^II‐Aryl Complex

Cited by 105 publications

References 68 publications

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

Nickel‐Catalyzed C‐Heteroatom Cross‐Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination

Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

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