New horizons in low oxidation state group 2 metal chemistry

Chemical Communications, Год журнала: 2021, Номер 57(74), С. 9354 - 9365

Опубликована: Янв. 1, 2021

Since the seminal report on Mg in +I oxidation state 2007, low-valent complexes featuring a MgI-MgI bond developed from trophy molecules to state-of-the-art reducing agents. Despite increasing interest low-valency of other group 2 metals, this area was restricted for long time rare example CaI(arene)CaI inverse sandwich. This feature article focuses most recent developments field, highlighting breakthroughs Be, and Ca. The more exotic metal Be first be isolated as zero-valent complex which could oxidized BeI species. There also has been breaking with superbulky β-diketiminate ligands (BDI) that suppress (BDI)Mg-Mg(BDI) formation. led Mg-Mg elongation or Mg-N cleavage. Several reports attempts isolate (BDI)Mg˙ radicals by combinations ligand bulk, addition neutral UV(vis) irradiation reduction aromatic solvents, underscoring high reactivity these open shell Only recently, were introduced. Double (BDI)MgI Na gave [(BDI)Mg-]Na+. Mg0 crystallized dimer Na+ cations bridge two (BDI)Mg- anions react nucleophiles. Thermal decomposition spontaneous formation Na0 trinuclear (BDI)MgMgMg(BDI) complex. mixed-valence Mg3-complex is prime fleeting multinuclear Mgn intermediates discussed way Grignard reagent. Attempts prepare CaI compounds (BDI)CaI dearomatization arene solvents: (BDI)Ca(arene)Ca(BDI). Reduction alkanes prevented pathway but N2 isolation (BDI)Ca(N2)Ca(BDI), representing molecular nitrogen fixation an early main metal. As N22- anion reacts cases very strong two-electron reductant, LCa(N2)CaL seen synthon hitherto elusive CaI-CaI complexes. Theoretical calculations suggest participation Ca d-orbitals relevant activation. These chemistry will revive undoubtly lead new reactivities applications.

Язык: Английский

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Transition-Metal Chemistry of the Heavier Alkaline Earth Atoms Ca, Sr, and Ba

Accounts of Chemical Research, Год журнала: 2021, Номер 54(15), С. 3071 - 3082

Опубликована: Июль 15, 2021

ConspectusAlkaline earth elements beryllium, magnesium, calcium, strontium, and barium with an ns2 valence-shell configuration are usually classified as main-group that belong to the s-block atoms. For a long time, were considered be rather chemically uninteresting atomic species due preconceived ideas about bonding, structure, reactivity. They typically use two ns valence electrons in forming ionic salt compounds metal formal oxidation state of +2. heavier alkaline atoms, barium, their (n – 1)d orbitals (AOs) empty but lie close energy np orbitals. Earlier theoretical investigations have already suggested these can employ AOs some extent form polar bonds divalent which centers sufficiently positively charged. The d orbital involvement increases from Ca Sr markedly Ba. Thus, has been termed honorary transition metal.Recently, molecular complexes Ca, Sr, Ba prepared gas phase low-temperature solid neon matrix detected by infrared spectroscopy. An analysis electronic structures [Ba(CO)]+, [Ba(CO)]−, saturated coordinated octacarbonyls [M(CO)8] [M(CO)8]+, isoelectronic dinitrogen [M(N2)8] [M(N2)8]+, tribenzene [M(Bz)3] (M = Ba) revealed metal–ligand bonding straightforwardly discussed using traditional Dewar–Chatt–Duncanson (DCD) model classical transition-metal complexes. explained → ligand π back donation occupied vacant antibonding ligands concomitant σ MOs In addition, heteronuclear Ca–Fe carbonyl cation also produced phase. Bonding coordination [CaFe(CO)10]+ complex implies it described interactions between [Ca(CO)6]2+ fragment [Fe(CO)4]− anion Fe d–d dative bond. nature metal–metal was quantitatively elucidated decomposition conjunction natural for chemical (EDA-NOCV) method, indicate metals dominant participating covalent interactions, just typical metals. results much richer chemistry than previously thought. These findings, along earlier studies, suggest atoms should main group periodic table elements. This interesting structural chemistry, together recently reported examples spectacular reactivity, establishes exciting promising research targets current research.

Язык: Английский

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Synthesis and reactivity of low-oxidation-state alkaline earth metal complexes

Nature Synthesis, Год журнала: 2022, Номер 1(6), С. 439 - 448

Опубликована: Июнь 2, 2022

Язык: Английский

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Nitrogen fixation and transformation with main group elements

Chemical Society Reviews, Год журнала: 2022, Номер 51(10), С. 3846 - 3861

Опубликована: Янв. 1, 2022

In this tutorial, we introduced the fundamental aspects of nitrogen fixation, summarized recent progresses with main group elements and tried to make clear clue for further developments.

Язык: Английский

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Transition‐Metal‐Free Barium Hydride Mediates Dinitrogen Fixation and Ammonia Synthesis

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(39)

Опубликована: Авг. 3, 2022

Transition-metal-mediated dinitrogen fixation has been intensively investigated. The employment of main group elements for this vital reaction recently sparked interest because new chemistry. We report ammonia synthesis via a chemical looping process mediated by transition-metal-free barium hydride (BaH2 ). Experimental and computational studies reveal that the introduction hydrogen vacancies is essential creating multiple coordinatively unsaturated Ba sites N2 activation. adjacent lattice hydridic (H- ) then undergoes both reductive elimination protonation to convert NHx . production rate supports hydride-vacancy mechanism route far exceeds catalytic process. BaH2 -mediated prospects in future technologies using materials.

Язык: Английский

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Electron deficient boron-doped amorphous carbon nitride to uphill N2 photo-fixation through π back donation

Applied Catalysis B Environment and Energy, Год журнала: 2022, Номер 321, С. 122070 - 122070

Опубликована: Окт. 12, 2022

Язык: Английский

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Atomically Dispersed Alkaline‐Earth Metals as Active Centers for CO₂ Electroreduction to Exclusively Produce Formate

Small Structures, Год журнала: 2023, Номер 4(7)

Опубликована: Янв. 4, 2023

Electrocatalytic CO 2 reduction reaction (CO RR) to produce formate (HCOOH) attracts special interest in the upgrade of waste . For selective conversion into HCOOH, preferable binding *OCHO compared with *COOH is a prerequisite, which presents great challenge rational design catalytic active center. Recently, alkaline‐earth (AE) metals as centers have been reported for electrocatalysis. Herein, feasibility AE heterogeneous catalysis electrocatalytic RR toward HCOOH based on series metal single‐atom catalysts (SACs) theoretically studied. High‐throughput first‐principles calculations reveal that, all studied systems, preferably adsorb *OCHO, enabling exclusive production. Especially, Mg SACs embedded graphene and Ca SAC anchored g‐C N can efficiently convert under near‐zero potential, both systems exhibit high stability. Mechanistic investigation indicates that are highly ionic, strongly bind mainly through electrostatic attraction interaction. This study lays theoretical foundation efficient electroreduction selectivity, further emphasizes potential catalysis.

Язык: Английский

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Stable Ketenyl Anions via Ligand Exchange at an Anionic Carbon as Powerful Synthons**

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(15)

Опубликована: Фев. 20, 2023

Under an atmosphere of carbon monoxide (CO), a (phosphino)diazomethyl anion salt [[P]-CN2 ][K(18-C-6)(THF)] (1) ([P]=[(CH2 )(NDipp)]2 P; 18-C-6=18-crown-6; Dipp=2,6-diisopropylphenyl) undergoes facile N2 /CO exchange reaction giving the (phosphino)ketenyl [[P]-CCO][K(18-C-6)] (2). Oxidation 2 with elemental Se affords (selenophosphoryl)ketenyl [P](Se)-CCO][K(18-C-6)] (3). These ketenyl anions feature strongly bent geometry at P-bound and this atom is highly nucleophilic. The electronic structure [[P]-CCO]- examined by theoretical studies. Reactivity investigations demonstrate as versatile synthon for derivatives ketene, enolate, acrylate acrylimidate moieties.

Язык: Английский

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The borderless world of chemical bonding across the van der Waals crust and the valence region

Chemical Science, Год журнала: 2023, Номер 14(42), С. 11647 - 11688

Опубликована: Янв. 1, 2023

The definition of the van der Waals crust as spherical section between atomic radius and an element is discussed a survey application penetration index two interacting atoms in wide variety covalent, polar, coordinative or noncovalent bonding situations presented. It shown that this newly defined parameter permits comparison pairs structural computational studies independently atom sizes.

Язык: Английский

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Coordination and Activation of N₂ at Low‐Valent Magnesium using a Heterobimetallic Approach: Synthesis and Reactivity of a Masked Dimagnesium Diradical**

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(37)

Опубликована: Июль 21, 2023

Abstract The activation of dinitrogen (N 2 ) by transition metals is central to the highly energy intensive, heterogeneous Haber–Bosch process. Considerable progress has been made towards more sustainable homogeneous activations N with d‐ and f‐block metals, though little success had main group metals. Here we report that reduction a bulky magnesium(II) amide [( TCHP NON)Mg] ( NON=4,5‐bis(2,4,6‐tricyclohexylanilido)‐2,7‐diethyl‐9,9‐dimethyl‐xanthene) 5 % w/w K/KI yields magnesium‐N complex [{K( NON)Mg} (μ‐N )]. DFT calculations experimental data show unit in reduced 2− dianion, via transient anionic magnesium(I) radical. compound readily reductively activates CO, H C 4 , reactions which it acts as masked dimagnesium(I) diradical.

Язык: Английский

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