Recent advances in the chemistry and applications of N-heterocyclic carbenes

Nature Reviews Chemistry, Год журнала: 2021, Номер 5(10), С. 711 - 725

Опубликована: Сен. 3, 2021

Язык: Английский

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Boron: Its Role in Energy‐Related Processes and Applications

Angewandte Chemie International Edition, Год журнала: 2019, Номер 59(23), С. 8800 - 8816

Опубликована: Окт. 18, 2019

Abstract Boron's unique position in the Periodic Table, that is, at apex of line separating metals and nonmetals, makes it highly versatile chemical reactions applications. Contemporary demand for renewable clean energy as well energy‐efficient products has seen boron playing key roles energy‐related research, such 1) activating synthesizing energy‐rich small molecules, 2) storing electrical energy, 3) converting into light. These applications are fundamentally associated with boron's characteristics, its electron‐deficiency availability an unoccupied p orbital, which allow formation a myriad compounds wide range physical properties. For example, ability to achieve full octet electrons four covalent bonds negative charge led synthesis variety borate anions high electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances study processes

Язык: Английский

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Beyond Ammonia: Nitrogen–Element Bond Forming Reactions with Coordinated Dinitrogen

Chemical Reviews, Год журнала: 2020, Номер 120(12), С. 5637 - 5681

Опубликована: Май 27, 2020

The functionalization of coordinated dinitrogen to form nitrogen–element bonds en route nitrogen-containing molecules is a long-standing challenge in chemical synthesis. strong triple bond and the nonpolarity N2 molecule pose thermodynamic kinetic challenges for promoting reactivity. While heterogeneous, homogeneous, biological catalysts are all known catalytic nitrogen fixation ammonia, synthesis more complicated organic has far less precedent. example silyl radical additions silylamines stands as lone reaction involving product other than ammonia. This Review surveys field molecular transition metal complexes well recent boron examples formation bonds. Emphasis placed on coordination activation modes various compounds from across series how these structures can rationally inform reactivity studies. Over past few decades, evolved addition carbon electrophiles manner similar that protonation reactions organometallic-inspired reactivity, including insertions, 1,2-additions, cycloadditions. Various N–C, N–Si, N–B bond-forming have been discovered, highlighting chemistry not but rather removal functionalized ligand sphere metal.

Язык: Английский

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Dinitrogen complexation and reduction at low-valent calcium

Science, Год журнала: 2021, Номер 371(6534), С. 1125 - 1128

Опубликована: Март 11, 2021

Calcium catches dinitrogen Although lithium reduces dinitrogen, the other alkali and alkaline Earth metals have proven largely inert to gas under ambient conditions. Rösch et al. report that with just right β-diketiminate ligand an assist from potassium as terminal reductant, calcium can mediate reduction. Crystallography spectroscopic characterization revealed a product in which doubly reduced adopted side-on bridging motif between two centers. A subsequent reaction coordinated tetrahydrofuran appeared release diazene. Science , this issue p. 1125

Язык: Английский

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Diverse Uses of the Reaction of Frustrated Lewis Pair (FLP) with Hydrogen

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(48), С. 20002 - 20014

Опубликована: Ноя. 17, 2021

The articulation of the notion "frustrated Lewis pairs" (FLPs) emerged from discovery that H2 can be reversibly activated by combinations sterically encumbered main group acids and bases. This has prompted numerous studies focused on various perturbations acid/base applications to organic reductions. Perspective focuses new directions developments are emerging this FLP chemistry involving hydrogen. Three areas discussed including approaches reductions, reductions small molecules, advances in heterogeneous systems. These foci serve illustrate despite having its roots chemistry, simple concept FLPs is being applied across discipline.

Язык: Английский

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Isolated Boron Sites for Electroreduction of Dinitrogen to Ammonia

ACS Catalysis, Год журнала: 2020, Номер 10(3), С. 1847 - 1854

Опубликована: Янв. 2, 2020

Exploring electrocatalysts with high activity is essential for the production of ammonia via an electrochemical routine. By employing density functional theory calculations, we investigated nitrogen reduction reaction (eNRR) on binary metal borides, a model system borides. To elaborate mechanisms, molybdenum borides (Mo2B, α-MoB, and MoB2) were first modeled; results indicate that crystal structures greatly impact N2 adsorption therefore electrocatalytic activity. Our electronic structure investigation suggests boron p-orbital hybrids dinitrogen π*-orbital, population p−π*-orbital determine strength. Therefore, isolated site Mo2B less filled pz-orbital benefits activation weaken triple bond dinitrogen. This sites concept was successfully extended to other in form M2B (M stands Ti, Cr, Mn, Fe, Co, Ni, Ta, W). Mo2B, Fe2B, Co2B discovered as most promising candidates low limiting potentials due appropriate strength intermediates led by moderate pz filling. work provides insights designing eNRR electrocatalysts.

Язык: Английский

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Where silylene–silicon centres matter in the activation of small molecules

Chemical Society Reviews, Год журнала: 2020, Номер 49(18), С. 6733 - 6754

Опубликована: Янв. 1, 2020

Small molecules such as H2, N2, CO, NH3, O2 are ubiquitous stable species and their activation role in the formation of value-added products fundamental importance nature industry. The last few decades have witnessed significant advances chemistry heavy low-coordinate main-group elements, with a plethora newly synthesised functional compounds, behaving like transition-metal complexes respect to facile small molecules. Among them, silylenes received particular attention this vivid area research showing even metal-free bond catalysis. Recent striking discoveries take advantage narrow HOMO-LUMO energy gap Lewis acid-base bifunctionality divalent Si centres. review is devoted recent using isolable corresponding silylene-metal for but inert COx, N2O, O2, H2O, C2H4 E4 (E = P, As).

Язык: Английский

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Activation of Dinitrogen by Polynuclear Metal Complexes

Chemical Reviews, Год журнала: 2020, Номер 120(12), С. 5517 - 5581

Опубликована: Май 4, 2020

Activation of dinitrogen plays an important role in daily anthropogenic life, and the processes by which this fixation occurs have been a longstanding significant research focus within community. One major fields activation is use multimetallic compounds to reduce and/or activate N2 into more useful nitrogen-atom source, such as ammonia. Here we report comprehensive review multimetallic-dinitrogen complexes their utility toward activation, beginning with d-block metals from Group 4 11, then extending 13 (which exclusively populated B complexes), finally rare-earth actinide species. The considers all polynuclear metal aggregates containing two or centers coordinated activated (i.e., partial complete cleavage triple bond observed product). Our survey includes mononuclear are used building blocks generate homo- heteromultimetallic species, allow one evaluate potential heterometallic species for activation. We highlight some common trends throughout periodic table, differences between coordination modes it relates functionalization effect polarizing bridging ligand employing different ions differing Lewis acidities. By providing treatment Review aims outline past provide future directions continued area.

Язык: Английский

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Nitrogen Fixation via Splitting into Nitrido Complexes

Chemical Reviews, Год журнала: 2021, Номер 121(11), С. 6522 - 6587

Опубликована: Май 11, 2021

The large carbon footprint of the Haber–Bosch process, which provides ammonia for fertilizers but also feedstock all nitrogenous commercial products, has fueled quest alternative synthetic strategies to nitrogen fixation. Owing extraordinarily strong N≡N triple bond, key step reaction, i.e., dissociative adsorption N2, requires high temperatures. Since first report in 1995, a wide variety molecular transition metal and f-block compounds have been reported that can fully cleave N2 at ambient conditions form well-defined nitrido complexes. We here provide comprehensive survey current state splitting reactions solution follow-up transfer reactivity. Particular emphasis is put on electronic structure requirements formation suitable precursors their N–N scission prospects synthesis containing products will be discussed, ranging from heterocumulenes organic amines, amides or nitriles via proton coupled electron transfer, carbonylation, electrophilic functionalization derived Accomplishments challenges fixation are presented offer guidelines development catalytic platforms.

Язык: Английский

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MBenes: emerging 2D materials as efficient electrocatalysts for the nitrogen reduction reaction

Nanoscale Horizons, Год журнала: 2020, Номер 5(7), С. 1106 - 1115

Опубликована: Янв. 1, 2020

MBenes, an emerging family of two-dimensional (2D) transition metal borides, have recently been synthesized in experiment and hold great promise for 2D ferromagnets ion batteries. With a well-defined layered structure outstanding electrical conductivity, MBenes provide ideal platform exploring the catalytic behavior boride surfaces at atomic level. Herein, we exploit ten kinds electrocatalysis N2 reduction reaction (NRR). By comprehensive first-principles calculations, show that high stability aqueous environments excellent selectivity toward NRR against hydrogen evolution (HER). Intriguingly, both surface boron atoms can serve as active sites owing to co-existence occupied unoccupied p (d) states (metal) atoms, while centers even superior activity compared atoms. Moreover, these borides be tuned by engineering their work function. Our theoretical results shine light on utilizing new category non-precious catalysts nitrogen fixation, illuminate fundamental principles controlling performance.

Язык: Английский

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