Synthesis of a stable crystalline nitrene

Science, Journal Year: 2024, Volume and Issue: 385(6706), P. 318 - 321

Published: June 13, 2024

Nitrenes are a highly reactive, yet fundamental, compound class. They possess monovalent nitrogen atom and usually short life span, typically in the nanosecond range. Here, we report on synthesis of stable nitrene by photolysis arylazide M

Language: Английский

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Red-Light-Active N,C,N-Pincer Bismuthinidene: Excited State Dynamics and Mechanism of Oxidative Addition into Aryl Iodides

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 10, 2025

Despite the progress made in field of synthetic organic photocatalysis over past decade, use higher wavelengths, especially those deep-red portion electromagnetic spectrum, remains comparatively rare. We have previously disclosed that a well-defined N,C,N-pincer bismuthinidene (1a) can undergo formal oxidative addition into wide range aryl electrophiles upon absorption low-energy red light. In this study, we map out photophysical dynamics 1a and glean insights nature excited state responsible for activation electrophiles. Transient emission techniques reveal that, irradiation with light, complex undergoes direct S0 → S1 metal-to-ligand charge transfer (MLCT) transition, followed by rapid intersystem crossing (ISC) to highly reducing emissive triplet (−2.61 V vs Fc+/0 MeCN). The low dissipative losses incurred during ISC (∼6% incident light energy) help rationalize ability convert useful chemical energy. Spectroelectrochemical computational data support charge-separated excited-state structure radical-anion character on ligand radical-cation bismuth. Kinetic studies competition experiments afford mechanism iodides; concerted inner-sphere processes from are ruled out, strongly supporting pathway proceeds via outer-sphere dissociative electron transfer.

Language: Английский

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Bi-Catalyzed Trifluoromethylation of C(sp²)–H Bonds under Light

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(47), P. 25538 - 25544

Published: Nov. 14, 2023

We disclose a Bi-catalyzed C–H trifluoromethylation of (hetero)arenes using CF3SO2Cl under light irradiation. The catalytic method permits the direct functionalization various heterocycles bearing distinct functional groups. structural and computational studies suggest that process occurs through an open-shell redox manifold at bismuth, comprising three unusual elementary steps for main group element. cycle starts with rapid oxidative addition to low-valent Bi(I) catalyst, followed by light-induced homolysis Bi(III)–O bond generate trifluoromethyl radical upon extrusion SO2, is closed hydrogen-atom transfer Bi(II) intermediate.

Language: Английский

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Ligand-enforced geometric constraints and associated reactivity in p-block compounds

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 53(2), P. 764 - 792

Published: Dec. 15, 2023

This review presents a group-wise summary of ligand enforced non-VSEPR geometries in compounds the p-block elements and discusses emergent consequences for reactivity.

Language: Английский

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Oxidative Addition of Aryl Electrophiles into a Red-Light-Active Bismuthinidene

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(34), P. 18742 - 18747

Published: Aug. 21, 2023

The oxidative addition of aryl electrophiles is a fundamental organometallic reaction widely applied in the field transition metal chemistry and catalysis. However, analogous version based on main group elements still remains largely underexplored. Here, we report ability well-defined organobismuth(I) complex to undergo formal with wide range electrophiles. process facilitated by reactivity both ground excited states N,C,N-bismuthinidenes upon absorption low-energy red light.

Language: Английский

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Low-energy photoredox catalysis

Nature Reviews Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 11, 2024

Language: Английский

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Decarboxylative stereoretentive C–N coupling by harnessing aminating reagent

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: May 6, 2024

Abstract In recent decades, strategies involving transition-metal catalyzed carbon-carbon or carbon-heteroatom bond coupling have emerged as potent synthetic tools for constructing intricate molecular architectures. Among these, decarboxylative carbon-nitrogen formation using abundant carboxylic acids their derivatives has garnered notable attention accessing alkyl- arylamines, one of key pharmacophores. While several amination methods been developed, the involvement a common carboradical intermediate currently poses challenges in achieving stereospecific transformation toward chiral alkylamines. Herein, we present base-mediated, stereoretentive amidation by harnessing 1,4,2-dioxazol-5-one reactive and robust amidating reagent under transition-metal-free ambient conditions, encompassing all types primary, secondary tertiary acids, thereby providing access to important pharmacophore, α-chiral amines. This method exhibits high functional group tolerance, convenient scalability, ease applicability 15 N-isotope labeling, thus accentuating its utilities. Experimental computational mechanistic investigations reveal sequence elementary steps: i) nucleophilic addition carboxylate dioxazolone, ii) rearrangement form dicarbonyl N-hydroxy intermediate, iii) conversion hydroxamate, followed Lossen-type rearrangement, finally, iv) reaction situ generated isocyanate with leading C–N manner.

Language: Английский

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Organobismuth Compounds as Aryl Radical Precursors via Light-Driven Single-Electron Transfer

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(4), P. 2664 - 2670

Published: Feb. 6, 2024

A light-driven method for the generation of aryl radicals from triarylbismuth(III) and (V) reagents is described. Aryl radical proposed to occur through ligand-assisted mesolytic cleavage an organobismuth(IV) intermediate generated either oxidation BiIII or reduction BiV. This mode demonstrated be compatible with a range bimolecular arylations, including hydroarylation electron-deficient olefins arylation diboronates, disulfides, sulfonyl cyanides, phosphites, isocyanides. The intermediacy supported by trapping clock experiments, BiIV–aryl mesolysis computationally.

Language: Английский

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Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

Beilstein Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 20, P. 346 - 378

Published: Feb. 21, 2024

Due to their ease of preparation, stability, and diverse reactivity, N -hydroxyphthalimide (NHPI) esters have found many applications as radical precursors. Mechanistically, NHPI undergo a reductive decarboxylative fragmentation provide substrate capable engaging in transformations. Their reduction via single-electron transfer (SET) can occur under thermal, photochemical, or electrochemical conditions be influenced by number factors, including the nature electron donor, use Brønsted Lewis acids, possibility forming charge-transfer complexes. Such versatility creates opportunities influence reaction conditions, providing parameters with which control reactivity. In this perspective, we an overview different mechanisms for reactions involving esters, emphasis on recent additions, cyclizations cross-coupling reactions. Within these classes, discuss utility eye towards continued development complexity-generating

Language: Английский

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Stabilizing Monoatomic Two-Coordinate Bismuth(I) and Bismuth(II) Using a Redox Noninnocent Bis(germylene) Ligand

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(9), P. 6025 - 6036

Published: Feb. 26, 2024

The formation of isolable monatomic BiI complexes and BiII radical species is challenging due to the pronounced reducing nature metallic bismuth. Here, we report a convenient strategy tame atoms by taking advantage redox noninnocent character new chelating bis(germylene) ligand. remarkably stable novel cation complex 4, supported bis(iminophosphonamido-germylene)xanthene ligand [(P)GeII(Xant)GeII(P)] 1, [(P)GeII(Xant)GeII(P) = Ph2P(NtBu)2GeII(Xant)GeII(NtBu)2PPh2, Xant 9,9-dimethyl-xanthene-4,5-diyl], was synthesized two-electron reduction cationic BiIIII2 precursor 3 with cobaltocene (Cp2Co) in molar ratio 1:2. Notably, owing germylene moieties, positive charge 4 migrates one Ge ligand, giving rise germylium(germylene) as suggested DFT calculations X-ray photoelectron spectroscopy (XPS). Likewise, migration results bis(germylium)BiIIII2 complex. delocalization engenders much higher stability comparison an isoelectronic two-coordinate Pb0 analogue (plumbylone; decomposition below −30 °C). Interestingly, 4[BArF] undergoes reversible single-electron transfer (SET) reaction (oxidation) afford 5 5[BArF]2. According electron paramagnetic resonance (EPR) spectroscopy, unpaired predominantly resides at atom. Extending reactivity 4[OTf] employing AgOTf MeOTf affords BiIII(OTf)2 7 BiIIIMe 8, respectively, demonstrating high nucleophilic 4.

Language: Английский

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