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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Combining geometric constraint and redox non-innocence within an ambiphilic PBiP pincer ligand

Chemical Science, Journal Year: 2024, Volume and Issue: 15(16), P. 6036 - 6043

Published: Jan. 1, 2024

The first pincer ligand featuring a strictly T-shaped pnictogen donor moiety was synthesised. PBiP ligand's redox activity facilitates unprecedented ambiphilic bonding of the Bi centre with transition metals through Bi(6p) orbital.

Language: Английский

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Transient Triplet Metallopnictinidenes M–Pn (M = Pd^II, Pt^II; Pn = P, As, Sb): Characterization and Dimerization

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

Published: Jan. 29, 2025

Nitrenes (R–N) have been subject to a large body of experimental and theoretical studies. The fundamental reactivity this important class transient intermediates has attributed their electronic structures, particularly the accessibility triplet vs singlet states. In contrast, structure trends along heavier pnictinidene analogues (R–Pn; Pn = P–Bi) are much less systematically explored. We here report synthesis series metallodipnictenes, {M–Pn═Pn–M} (M PdII, PtII; P, As, Sb, Bi) characterization metallopnictinidene intermediates, {M–Pn} for Sb. Structural, spectroscopic, computational analysis revealed spin ground states metallopnictinidenes with characteristic series. comparison nitrene, pnictinidenes exhibit lower-lying state SOMOs excited states, thus suggesting increased electrophilic reactivity. Furthermore, splitting magnetic microstates is beyond phosphinidenes {M–P} dominated by heavy pnictogen atom induced spin–orbit coupling.

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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Reductive Cyclopropanation through Bismuth Photocatalysis

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(32), P. 22140 - 22144

Published: Aug. 5, 2024

We present here a catalytic method based on low-valent Bi complex capable of cyclopropanation double bonds under blue LED irradiation. The catalysis features various unusual Bi-based organometallic steps, namely, (1) two-electron inner sphere oxidative addition Bi(I) to CH2I2, (2) light-induced homolysis the Bi(III)–CH2I bond, (3) subsequent iodine abstraction-ring-closing, and (4) reduction Bi(III) with an external reducing agent close cycle. Stoichiometric experiments support proposed mechanism. This protocol represents unique example reductive photocatalytic process bismuth radical catalysis.

Language: Английский

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Carbodiphosphorane-Activated Distibene and Dibismuthene Dications

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 19, 2024

Low-valent antimony and bismuth have emerged as novel platforms for achieving reversible small-molecule activation at main-group metals. Although various examples of oxidative addition reactions monomeric Sb(I) Bi(I) been reported, the chemistry heavy group 15 Sb(I)═Sb(I)/Bi(I)═Bi(I) double bonds toward small molecules remains largely unexplored. In this study, we present a straightforward synthesis distibene dibismuthene dications coordinated with neutral carbodiphosphorane (CDP) ligand. The nonbonding interactions between occupied p-orbital CDP ligand π-bonding orbital Sb═Sb/Bi═Bi yield compounds exceptionally HOMO-LUMO gaps. addition, reduction steric hindrance compared to known derivatives stabilized bulky aryl groups allows better accessibility bonds. This high reactivity is demonstrated in diphenyldisulfide well [2+2] cycloadditions alkynes. Additionally, Sb═Sb bond reversibly adds 2,3-dimethylbutadiene [4+2] cycloaddition reaction.

Language: Английский

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Tetra-Cationic Distibane Stabilized by Bis(α-iminopyridine) and Its Reactivity

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

Published: Jan. 16, 2025

The work establishes the salt of a tetra-cationic distibane, [L2Sb2][CF3SO3]4 = [1]2[OTf]4 (CF3SO3 OTf), stabilized by bis(α-iminopyridine) ligand L, defying Coulombic repulsion. synthetic approach involved dehydrocoupling reaction when mixture L and Sb(OTf)3 in 1:1 ratio was treated with Et3SiH/LiBEt3H as hydride source. Compound also achieved from [LSbCl][OTf]2 precursor using Et3SiH. Dissolution polar solvents unveiled formation persistent L-stabilized dicationic Sb(II) radical monomer [1][OTf]2, while addition Me3SiOTf regenerated dimer [1]2[OTf]4. homolytic cleavage Sb–Sb bond [1]24+ has manifested exchange reactions between Ph2Ch2 (Ch S, Se), giving [LSb(SPh)][OTf]2 [2][OTf]2 [LSb(SePh)][OTf]2 [3][OTf]2, respectively, acetonitrile. Reaction p-benzoquinone gave [L2Sb2(C6H4O2)][OTf]4 [4][OTf]4. An interesting oxygen atom insertion occurred 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to give [L2Sb2O][ OTf]4 [5][OTf]4. oxo-bridged compound [5][OTf]4 obtained exposure open air. strong Mn–Mn [Mn2(CO)10] could be cleaved reacting presence pyridine form [LSbMn(CO)5][ OTf]2 [6][OTf]2. On other hand, [Co2(CO)8] oxidative product [L2Sb2Co(CO)3][OTf]3 [7][OTf]3. compounds were characterized both solid solution states. Computational studies comprehensive understanding experimental findings.

Language: Английский

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Nitrogen-Based Ligands in the Coordination Sphere of Bismuth

Structure and bonding, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Language: Английский

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Recent advances in heavier Group 15 (P, As, Sb, Bi) radical chemistry – frameworks, small molecule reactivity, and catalysis

Dalton Transactions, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

New developments in the area of heavier pnictogen-based radicals continue to be reported, along with small molecule reactivity and newly discovered catalytic reactions.

Language: Английский

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Catalyst-controlled regiodivergence and stereodivergence in formal cross-[4+2] cycloadditions: The unique effect of bismuth(III)

Science Advances, Journal Year: 2025, Volume and Issue: 11(13)

Published: March 26, 2025

The [4+2] cycloaddition is crucial for constructing six-membered rings in pharmaceuticals and natural products. Cross-[4+2] cycloadditions offer greater product diversity than traditional diene-dienophile reactions due to multiple possible pathways. However, precise control over regio- stereoselectivity various isomers remains a great challenge. This study reports catalyst-controlled regiodivergent formal cross-cycloadditions of acyclic dienes enones, significantly enhancing access diverse pyrazole-fused spirooxindoles. Chiral phosphoric acid (CPA) catalysis enables endoselective cycloadditions, while Bi(III) with CPA ligand yields [2+4] products high stereoselectivity. A Claisen rearrangement the adduct produces exo-selective product, further increasing stereochemical enabling synthesis six stereo-isomers from single substrate set. DFT calculations reveal that reverses regioselectivity by repositioning reactants pocket stabilizing enone oxygen’s negative charge. In addition, 3as demonstrates therapeutic potential against triple-negative breast cancer, an IC 50 8.5 μM MDA-MB-453 cells.

Language: Английский

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