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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Metallomimetic C–F Activation Catalysis by Simple Phosphines

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(3), P. 2005 - 2014

Published: Jan. 11, 2024

Delivering metallomimetic reactivity from simple p-block compounds is highly desirable in the search to replace expensive, scarce precious metals by cheap and abundant elements catalysis. This contribution demonstrates that catalysis, involving facile redox cycling between P(III) P(V) oxidation states, possible using only simple, cheap, readily available trialkylphosphines without need enforce unusual geometries at phosphorus or use external oxidizing/reducing agents. Hydrodefluorination aminodefluorination of a range fluoroarenes was realized with good very yields under mild conditions. Experimental computational mechanistic studies show phosphines undergo oxidative addition fluoroaromatic substrate via Meisenheimer-like transition state form fluorophosphorane. undergoes pseudotransmetalation step silane, initial fluoride transfer P Si, give experimentally observed phosphonium ions. Hydride hydridosilicate counterion then leads hydridophosphorane, which reductive elimination product reform phosphine catalyst. behavior analogous many classical transition-metal-catalyzed reactions so rare example both functional mechanistically catalysis main-group element system. Crucially, reagents used are commercially, easy handle, making these realistic prospect wide academic industrial settings.

Language: Английский

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Molecular-strain induced phosphinidene reactivity of a phosphanorcaradiene

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

Published: May 29, 2024

Abstract Phosphanorcaradienes are an appealing class of phosphorus compounds that can serve as synthons transient phosphinidenes. However, the synthesis such species is a formidable task owing to their intrinsic high reactivity. Herein we report straightforward synthesis, characterization and reactivity studies phosphanorcaradiene, in which one benzene rings flanking fluorenyl substituents intramolecularly dearomatized through attachment atom. It facilely obtained by reduction phosphorus(III) dichloride precursor with potassium graphite. Despite being thermally robust, it acts synthetic equivalent phosphinidene. reacts trimethylphosphine isonitrile yield phosphanylidene-phosphorane 1-phospha-3-azaallene, respectively. When treated two molar equivalents azide, iminophosphane bis(imino)phosphane isolated, Moreover, capable activating ethylene alkyne afford [1 + 2] cycloaddition products, well oxidative cleavage Si–H N–H bonds secondary phosphines. All reactions proceed smoothly at room temperature without presence transition metals. The driving force for these most likely ring-constraint three-membered PC 2 ring recovery aromaticity ring.

Language: Английский

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Hydrogen splitting at a single phosphorus centre and its use for hydrogenation

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(8), P. 1261 - 1266

Published: June 27, 2024

Language: Английский

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Reactivity of a Strictly T‐Shaped Phosphine Ligated by an Acridane Derived NNN Pincer Ligand

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(39)

Published: April 12, 2023

Abstract The steric tuning of a tridentate acridane‐derived NNN pincer ligand allows for the isolation strictly T‐shaped phosphine that exhibits ambiphilic reactivity. Well‐defined phosphorus‐centered reactivity towards nucleophiles and electrophiles is reported, contrasting with prior reports on this class compounds. Reactions oxidants are also described. latter result in two‐electron oxidation phosphorus atom from +III to +V accompanied by strong geometric distortion ligand. By contrast, cooperative activation E−H (HCl, HBcat, HOMe) bonds proceeds retention redox state. When using H 2 O as substrate, reaction results full disassembly its constituent atoms, highlighting potential platform small molecule reactions.

Language: Английский

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Mechanistic Studies on the Bismuth‐Catalyzed Transfer Hydrogenation of Azoarenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(49)

Published: Sept. 28, 2023

Organobismuth-catalyzed transfer hydrogenation has recently been disclosed as an example of low-valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide insights into a Bi-catalyzed azoarenes using p-trifluoromethylphenol (4) pinacolborane (5) hydrogen sources. A kinetic analysis elucidated the rate orders in all components catalytic reaction determined 1 (2,6-bis[N-(tert-butyl)iminomethyl]phenylbismuth) is resting state. In azobenzene 4, equilibrium between ⋅ [OAr]2 (Ar=p-CF3 -C6 H4 ) observed, thermodynamic parameters are established through variable-temperature NMR studies. Additionally, pKa -gated reactivity validating proton-coupled nature transformation. The ensuing crystallographically characterized, shown to be rapidly reduced presence 5. DFT calculations indicate rate-limiting transition state which initial N-H bond formed via concerted proton upon nucleophilic addition hydrogen-bonded adduct 4. These guided discovery second-generation catalyst, lower energy, leading at catalyst loadings cryogenic temperature.

Language: Английский

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Why Are Some Pnictogen(III) Pincer Complexes Planar and Others Pyramidal?

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(57)

Published: July 30, 2024

Geometrically-constrained pnictogen pincer complexes have emerged in recent years as platforms for unique stoichiometric and catalytic chemical transformations. These feature dynamic conformations ranging from fully planar at the centre to distorted-pyramidal geometries, well variation between phases. Although valued reactivity of is ascribed their there no unified model explain observed conformational outcomes across different ligands centres. Here we propose such a through computational analysis more than 1300 structures 64 (16 4 heavy pnictogens), explaining experimental observations making new predictions. By looking signatures bond stability (bond lengths, Wiberg indices) delocalization (NPA charges, Hirshfeld charges), our framework posits pnictogen-based σ-bonding effect that favours pyramidalization exists competition with ligand-based π-bonding planarity. Variations structure function identity, ligand tethering, electronics, aromaticity can be reconciled reference balance these two opposing forces. Careful consideration σ/π-bonding effects may aid rational design future predictable geometries reactivities.

Language: Английский

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A focus on phosphinophosphination of apolar bonds by a structurally constrained P–P bonded system

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

This article highlights recent work by Greb et al. on the phosphinophosphination of alkenes, alkynes, and carbonyls, with a focus how polarity P–P bond controls scope resulting reactivity.

Language: Английский

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Access to Bis-Silylene-Stabilized Group 13 Cations

Inorganic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 6, 2025

Herein, we report the isolation of pyridine moiety-functionalized SiNSi pincer-based bis-silylene ligand (1) and its reactivity toward various halide precursors (X = Br I) group 13 elements (M Al, Ga, In). This gave us straightforward access to pincer-coordinated cations (2–7). These complexes are duly characterized by single-crystal X-ray diffraction studies, multinuclear magnetic resonance spectroscopy (1H, 13C, 29Si), high-resolution mass spectrometry techniques. Their electronic properties were further analyzed with help quantum chemical calculations.

Language: Английский

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Zirconium-Mediated Carbon-Fluorine Bond Functionalisation Through Cyclohexyne “Umpolung”

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Polarity reversal, or "umpolung", is a widely acknowledged strategy to allow organic functional groups amenable react in alternative ways the usual preference set by their electronic features. In this article, we demonstrate that cyclohexyne umpolung, realized through complexation zirconocene, makes small strained cycloalkyne C-F bond functionalisation. Such strong activation chemistry unprecedented "free" aryne and alkyne chemistry. Our study also reveals reactivity of Zr-cyclohexyne complex highly sensitive degree fluorination heteroarene. addition, parasitic reactions ancillary ligand PMe3 were observed when pentafluoropyridine was substrate.

Language: Английский

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