Reactivity of a Hexaaryldiboron(6) Dianion as Boryl Radical Anions

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(25), P. 17348 - 17354

Published: June 12, 2024

Our study unveils a novel approach to accessing boryl radicals through the spontaneous homolytic cleavage of B–B bonds. We synthesized hexaaryl-substituted diboron(6) dianion, 1, via reductive coupling 9-borafluorene. Intriguingly, compound 1 exhibits ability undergo bond cleavage, leading formation radical anions, as confirmed by EPR studies, in presence 2.2.2-cryptand at room temperature. Moreover, it directly reacts with diphenylacetylene, producing an unprecedented 1,6-diborylated allene species, where phenyl ring is dearomatized. Density functional theory computational studies suggest that favored reaction path, and anion crucial for dearomatization. Additionally, achieves dearomative diborylation anthracene activation elemental sulfur/selenium under mild conditions. The borylation products have been successfully characterized NMR spectra, HRMS, X-ray single-crystal diffraction.

Language: Английский

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Isomeric Azulene-Based Carbon-Centered Radicals Derived from N-Heterocyclic Carbenes

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

Published: Feb. 12, 2025

Azulene (isomer with naphthalene), a representative nonalternant hydrocarbon, has attracted significant attention as building block for π-extended molecules owing to its distinctive electronic structure and physicochemical properties that differ from those of conventional alternant hydrocarbons. Nevertheless, the development stable carbon-centered radicals utilizing an azulene moiety remains relatively scarce. Herein, we report structures optical azulene-based radical isomers, 1 2, which were designed synthesized by attaching N-heterocyclic carbenes (NHCs) 6-position seven-membered ring or 2-position five-membered azulene, respectively. Density functional theory calculations reveal spin density in is primarily localized on indicating it cyclopentadienyl radicals, whereas predominantly distributed serving example cycloheptatrienyl radicals. Furthermore, although both 2 exhibit anti-Kasha emission, emission wavelength (λem ∼ 495 nm) significantly red-shifted compared 396 nm).

Language: Английский

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Dicationic Boron Derivatives of Schlenk’s and Thiele’s Hydrocarbon

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

Published: March 19, 2025

In recent years, neutral NHC-stabilized boryl radicals have been investigated as reactive species in various organic transformations. However, cationic boron significantly less explored. addition, boron-centered open-shell with S > 1/2 emerged attractive synthetic targets. this study, we provide a route to an radical cation salt of the weakly coordinating [Al(ORF)4]- (RF = C(CF3)3) anion. The procedure was extended dicationic diboron derivatives Schlenk's and Thiele's hydrocarbons meta- para-phenylene coupling units between spin centers. While most known isolable biradicals singlet ground-state thermally accessible triplet state, version hydrocarbon occupies spin-state, shown by combined electron paramagnetic resonance spectroscopy density functional theory studies. Furthermore, initial reactivity studies dications elemental sulfur diphenyldiselenide are presented.

Language: Английский

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Carborane–arene fused boracyclic analogues of polycyclic aromatic hydrocarbons accessed by intramolecular borylation

Chemical Science, Journal Year: 2024, Volume and Issue: 15(20), P. 7568 - 7575

Published: Jan. 1, 2024

Carborane fused boron doped polycyclic aromatic hydrocarbons were accessed by dehydrobrominative and dehydrogenative borylation.

Language: Английский

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Redox- and Charge-State Dependent Trends in 5, 6, and 7-Membered Boron Heterocycles: A Neutral Ligand Coordination Chemistry Approach to Boracyclic Cations, Anions, and Radicals

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(10), P. 1510 - 1522

Published: May 6, 2024

ConspectusBoron heterocycles represent an important subset of heteroatom-incorporated rings, attracting attention from organic, inorganic, and materials chemists. The empty pz orbital at the boron center makes them stand out as quintessential Lewis acidic molecules, also serving a means to modulate electronic structure photophysical properties in facile manner. As boracycles are ripe for extensive functionalization, they used catalysis, chemical biology, science, continue be explored synthons conjugated reagents. Neutral boron(III)-incorporated polycyclic molecules some most studied types boracycles, understanding their redox transformations is applications relying on electron transfer charge transport. While relevant species can often electrochemically observed, it remains challenging isolate characterize where and/or skeleton have been chemically reduced.We describe our recent work isolating 5-, 6-, 7-membered boracyclic radicals, anions, cations, focusing stabilization strategies, ligand-mediated bonding situations, reactivity. We present versatile neutral ligand coordination chemistry approach that permits transformation potent electrophiles powerful nucleophilic facilitate diverse bond activation chemistry. Although there wide range suitable stabilizing ligands, we employed both diamino-N-heterocyclic carbenes (NHCs) cyclic(alkyl)(amino) (CAACs), which led with tunable structures aromaticity trends. highlight successful isolation borafluorene radicals demonstrate reversible behavior, undergoing oxidation cation or reduction anion. anion synthon has prepare boryl main-group transition-metal bonds, luminescent oxabora-spirocycles, borafluorenate-crown ethers, CO-releasing via carbon dioxide activation. expanded 6-membered characterized bis(NHC-supported 9-boraphenanthrene)s corresponding bis(CAAC-stabilized 9-boraphenanthrene) biradical. detail interconvertible multiredox states boraphenalene, boraphenalenyl radical, anion, mimic charge-states all-hydrocarbon analogue. Reactivity studies displayed unusual reactivity multiple sites periphery tricyclic scaffold. Reduced borepins, containing heterocycles, isolated. stepwise one-pot synthesis combining halo-borepin precursor, CAAC, KC8 afford monomeric borepin anions. π-system was extended contain two rings fused pentacyclic scaffold, permitted diborepin biradicals dibora-quinone core.Our goal provide guide explaining current structure–function trends strategies redox-active boron-incorporated initiate rational design use these compounds across vast space.

Language: Английский

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Pentacyclic fused diborepinium ions with carbene- and carbone-mediated deep-blue to red emission

Chemical Science, Journal Year: 2024, Volume and Issue: 15(35), P. 14358 - 14370

Published: Jan. 1, 2024

Designing molecules that can undergo late-stage modifications resulting in specific optical properties is useful for developing structure-function trends materials, which ultimately advance optoelectronic applications. Herein, we report a series of fused diborepinium ions stabilized by carbene and carbone ligands (diamino-N-heterocyclic carbenes, cyclic(alkyl)(amino) carbodicarbenes, carbodiphosphoranes), including detailed bonding analysis. These are the first structurally confirmed examples diborepin dications detail how distortions core pentacyclic system impact aromaticity, stability, their light-emitting properties. Using same scaffold, coordinating were used to dramatically shift emission profile, exhibit colors ranging from blue red (358-643 nm). Notably, these access expanded regions visible spectrum compared known borepins, with quantum yields up 60%. Carbones determined be superior stabilizing ligands, improved stability solution solid states. Density functional theory was provide insight into as well transitions result observed photophysical

Language: Английский

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Crystalline Radical Anion of a Diboratriazole and Its Conversion to a Neutral Radical Driven by a Carbene

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(30), P. 20945 - 20950

Published: July 21, 2024

One-electron reduction of diboratriazole

Language: Английский

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Recent Advances in NIR‐Switchable Multi‐Redox Systems Based on Organic Molecules

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 6, 2024

Abstract Electrochromic systems capable of switching absorption in the near‐infrared (NIR) region (750–2500 nm) are attractive from viewpoint applications for material and life science, thus several examples have been reported to date. In general, development organic‐based is needed reduce environmental impact improve biocompatibility. Although extending switchable spectral range crucial application organic electrochromic molecules, NIR based on redox interconversion still a challenging issue regarding reversibility durability during interconversion. To overcome this potential instability, introduction heteroatoms into molecular backbone and/or π‐extension could be useful strategies terms effective delocalization charge spin corresponding states. review, we focus redox‐active well‐defined small molecules that enable ON/OFF precise control states, present recent studies their intrinsic electrochemical spectroscopic properties structural characterization charged

Language: Английский

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