Cyclic voltammetry and chronoamperometry: mechanistic tools for organic electrosynthesis

Chemical Society Reviews, Год журнала: 2023, Номер 53(2), С. 566 - 585

Опубликована: Дек. 5, 2023

This tutorial review explains the use of cyclic voltammetry and chronoamperometry to interrogate reaction mechanisms, optimize electrochemical reactions, or design new reactions.

Язык: Английский

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Interrogating the Mechanistic Features of Ni(I)-Mediated Aryl Iodide Oxidative Addition Using Electroanalytical and Statistical Modeling Techniques

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(15), С. 8689 - 8699

Опубликована: Апрель 4, 2023

While the oxidative addition of Ni(I) to aryl iodides has been commonly proposed in catalytic methods, an in-depth mechanistic understanding this fundamental process is still lacking. Herein, we describe a detailed study using electroanalytical and statistical modeling techniques. Electroanalytical techniques allowed rapid measurement rates for diverse set iodide substrates four classes catalytically relevant complexes (Ni(MeBPy), Ni(MePhen), Ni(Terpy), Ni(BPP)). With >200 experimental rate measurements, were able identify essential electronic steric factors impacting through multivariate linear regression models. This led classification mechanisms, either three-center concerted or halogen-atom abstraction pathway based on ligand type. A global heat map predicted was created shown applicable better reaction outcome case Ni-catalyzed coupling reaction.

Язык: Английский

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Mechanisms of Photoredox Catalysis Featuring Nickel–Bipyridine Complexes

ACS Catalysis, Год журнала: 2024, Номер 14(11), С. 9055 - 9076

Опубликована: Май 29, 2024

Metallaphotoredox catalysis can unlock useful pathways for transforming organic reactants into desirable products, largely due to the conversion of photon energy chemical potential drive redox and bond transformation processes. Despite importance these processes cross-coupling reactions other transformations, their mechanistic details are only superficially understood. In this review, we have provided a detailed summary various photoredox mechanisms that been proposed date Ni-bipyridine (bpy) complexes, focusing separately on photosensitized direct excitation reaction By highlighting multiple key findings, depict how mechanisms, which ultimately define substrate scope, themselves defined by ground- excited-state geometric electronic structures Ni-based intermediates. We further identify knowledge gaps motivate future studies development synergistic research approaches spanning physical, organic, inorganic chemistry communities.

Язык: Английский

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Photogenerated Ni(I)–Bipyridine Halide Complexes: Structure–Function Relationships for Competitive C(sp²)–Cl Oxidative Addition and Dimerization Reactivity Pathways

Inorganic Chemistry, Год журнала: 2023, Номер 62(24), С. 9538 - 9551

Опубликована: Июнь 6, 2023

We report the facile photochemical generation of a library Ni(I)-bpy halide complexes (Ni(I)(Rbpy)X (R = t-Bu, H, MeOOC; X Cl, Br, I) and benchmark their relative reactivity toward competitive oxidative addition off-cycle dimerization pathways. Structure-function relationships between ligand set are developed, with particular emphasis on rationalizing previously uncharacterized ligand-controlled high energy challenging C(sp2)-Cl bonds. Through dual Hammett computational analysis, mechanism formal is found to proceed through an SNAr-type pathway, consisting nucleophilic two-electron transfer Ni(I) 3d(z2) orbital Caryl-Cl σ* orbital, which contrasts observed for activation weaker C(sp2)-Br/I The bpy substituent provides strong influence reactivity, ultimately determining whether or even occurs. Here, we elucidate origin this as arising from perturbations effective nuclear charge (Zeff) center. Electron donation metal decreases Zeff, leads significant destabilization entire 3d manifold. Decreasing electron binding energies powerful donor activate These changes also prove have analogous effect dimerization, in Zeff leading more rapid dimerization. Ligand-induced modulation thus tunable target by can be altered, providing direct route stimulate stronger C-X bonds potentially unveiling new ways accomplish Ni-mediated photocatalytic cycles.

Язык: Английский

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Ultrafast Photophysics of Ni(I)–Bipyridine Halide Complexes: Spanning the Marcus Normal and Inverted Regimes

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(22), С. 15506 - 15514

Опубликована: Май 22, 2024

Owing to their light-harvesting properties, nickel–bipyridine (bpy) complexes have found wide use in metallaphotoredox cross-coupling reactions. Key these transformations are Ni(I)–bpy halide intermediates that absorb a significant fraction of light at relevant reaction irradiation wavelengths. Herein, we report ultrafast transient absorption (TA) spectroscopy on library eight complexes, the first such characterization any Ni(I) species. The TA data reveal formation and decay Ni(I)-to-bpy metal-to-ligand charge transfer (MLCT) excited states (10–30 ps) whose relaxation dynamics well described by vibronic Marcus theory, spanning normal inverted regions as result simple changes bpy substituents. While lifetimes relatively long for MLCT first-row transition metal duration precludes excited-state bimolecular reactivity photoredox We also present one-step method generate an isolable, solid-state species, which decouples light-initiated from dark, thermal cycles catalysis.

Язык: Английский

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Light-Induced Access to Carbazole-1,3-dicarbonitrile: A Thermally Activated Delayed Fluorescent (TADF) Photocatalyst for Cobalt-Mediated Allylations

The Journal of Organic Chemistry, Год журнала: 2022, Номер 88(10), С. 6390 - 6400

Опубликована: Ноя. 16, 2022

The stability of a photocatalyst under irradiation is important in photoredox applications. In this work, we investigated the thermally activated delayed fluorescence (TADF) {3DPAFIPN [2,4,6-tris(diphenylamino)-5-fluoroisophthalonitrile]}, recently employed photoredox-mediated processes, discovering that absence quenchers chromophore unstable and efficiently converted by with visible light into another species based on carbazole-1,3-dicarbonitrile moiety. new obtained itself TADF emitter finds useful applications transformations. At excited state, it strong reductant was applied to cobalt-mediated allylation aldehydes, whereas other TADFs (4CzIPN 3DPAFIPN) failed promote efficient photocatalytic cycles.

Язык: Английский

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Electronic Structures of Nickel(II)-Bis(indanyloxazoline)-dihalide Catalysts: Understanding Ligand Field Contributions That Promote C(sp²)–C(sp³) Cross-Coupling

Inorganic Chemistry, Год журнала: 2023, Номер 62(34), С. 14010 - 14027

Опубликована: Авг. 16, 2023

NiII(IB) dihalide [IB = (3aR,3a′R,8aS,8a′S)-2,2′-(cyclopropane-1,1-diyl)bis(3a,8a-dihydro-8H-indeno[1,2-d]-oxazole)] complexes are representative of a growing class first-row transition-metal catalysts for the enantioselective reductive cross-coupling C(sp2) and C(sp3) electrophiles. Recent mechanistic studies highlight complexity these ground-state cross-couplings but also illuminate new reactivity pathways stemming from one-electron redox their significant sensitivities to reaction conditions. For first time, diverse array spectroscopic methods coupled electrochemistry have been applied NiII-based precatalysts evaluate specific ligand field effects governing key Ni-based potentials. We experimentally demonstrate DMA solvent coordination catalytically relevant Ni complexes. Coordination is shown favorably influence redox-based steps prevent other deleterious equilibria. Combined with electronic structure calculations, we further provide direct correlation between intermediate frontier molecular orbital energies yields. Considerations developed herein use synergic electrochemical concepts catalyst design rationalization condition optimization.

Язык: Английский

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Strategies for Carbon Electrophile Addition to Carbonyls and Imines by Cobalt Catalysis

European Journal of Organic Chemistry, Год журнала: 2023, Номер 26(45)

Опубликована: Окт. 16, 2023

Abstract The addition of carbon electrophiles to carbonyls and imines has emerged as a valuable strategy for the construction C−C bonds. merger this concept with sustainable cobalt catalysis yielded numerous innovative methodologies. Remarkable functional group tolerance selectivity have been observed in many cases, providing reliable methods bond construction. cobalt‐catalyzed additions carbonyls, carboxylic acid derivatives described review include earliest reports, such Takai‐Utimoto Co/Cr co‐catalyzed their progression, well modern variants, exemplified by recent Co/photoredox protocols. systematic appraisal provides clearer perspective inspiration its further development.

Язык: Английский

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Automated approaches, reaction parameterisation, and data science in organometallic chemistry and catalysis: towards improving synthetic chemistry and accelerating mechanistic understanding

Digital Discovery, Год журнала: 2024, Номер 3(8), С. 1467 - 1495

Опубликована: Янв. 1, 2024

This review discusses the use of automation for organometallic reactions to generate rich datasets and, with statistical analysis and reaction component parameterisation, how mechanisms can be probed gain understanding.

Язык: Английский

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Cathodic tandem alkylation/dearomatization of heterocycles enabled by Al-facilitated carbonyl deoxygenation

Nature Communications, Год журнала: 2025, Номер 16(1)

Опубликована: Янв. 25, 2025

Язык: Английский

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