Metal-coordinated azoaromatics: Strategies for sequential azo-reduction, isomerization and application potential

Coordination Chemistry Reviews, Journal Year: 2022, Volume and Issue: 475, P. 214895 - 214895

Published: Oct. 21, 2022

Language: Английский

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Complexes Featuring a cis‐[MUM] Core (M=Rh, Ir): A New Route to Uranium‐Metal Multiple Bonds

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(21)

Published: March 24, 2023

Although examples of multiple bonds between actinide elements and main-group are quite common, studies the transition metals extremely rare owing to difficulties associated with their synthesis. Here we report first example molecular uranium complexes featuring a cis-[M →→${{\rm{ \mathbin{{\stackrel{\textstyle\rightarrow} { {\smash{\rightarrow}\vphantom{_{\vbox to.5ex{\vss}}}} } }} }}}$ U ←←${{\rm{ \mathbin{{\stackrel{\textstyle\leftarrow} {\smash{\leftarrow}\vphantom{_{\vbox M] core (M=Rh, Ir), which exhibits an unprecedented arrangement two M double dative bond linkages single center. These were prepared by reactions chlorine-bridged heterometallic [{U{N(CH3 )(CH2 CH2 NPi Pr2 )2 }(Cl)2 [(μ-Cl)M(COD)]2 }] Ir) MeMgBr or MeLi, new method for construction species U-M bonds. Theoretical calculations including dispersion confirmed presence in these complexes. This study not only enriches chemistry, but also provides opportunity explore bonding elements.

Language: Английский

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Terminal Imido Complexes of the Groups 9–11: Electronic Structure and Developments in the Last Decade

European Journal of Inorganic Chemistry, Journal Year: 2021, Volume and Issue: 2021(40), P. 4147 - 4166

Published: July 28, 2021

Abstract We thank the Fonds der Chemischen Industrie (Liebig fellowship for D.M.), German‐American Fulbright Commission (Fulbright‐Cottrell Award D.M.) as well Bavarian Equal Opportunities Sponsorship – Realization of Women in Research and Teaching (fellowship A.G.) financial support. RRZ Erlangen computational resources.

Language: Английский

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A Terminal Imido Complex of an Iron–Sulfur Cluster

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(23), P. 12802 - 12806

Published: March 27, 2021

Abstract We report the synthesis and characterization of first terminal imido complex an Fe–S cluster, (IMes) 3 Fe 4 S =NDipp ( 2 ; IMes=1,3‐dimesitylimidazol‐2‐ylidene, Dipp=2,6‐diisopropylphenyl), which is generated by oxidative group transfer from DippN to all‐ferrous cluster (PPh ). This two‐electron process achieved formal one‐electron oxidation imido‐bound site two IMes‐bound sites. Structural, spectroscopic, computational studies establish that Fe–imido best described as a high‐spin 3+ center, manifested in its long Fe−N(imido) distance 1.763(2) Å. Cluster abstracts hydrogen atoms 1,4‐cyclohexadiene yield corresponding anilido complex, demonstrating competency for C−H activation.

Language: Английский

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Between imide, imidyl and nitrene – an imido iron complex in two oxidation states

Chemical Science, Journal Year: 2022, Volume and Issue: 13(26), P. 7907 - 7913

Published: Jan. 1, 2022

Imidyl and nitrene metal species play an important role in the N-functionalisation of unreactive C-H bonds as well aziridination olefines. We report on synthesis trigonal imido iron complexes [Fe(NMes)L2]0,- (L = -N{Dipp}SiMe3); Dipp 2,6-diisopropyl-phenyl; Mes (2,4,6-trimethylphenyl) via reaction mesityl azide (MesN3) with linear precursors [FeL2]0,-. UV-vis-, EPR-, 57Fe Mössbauer spectroscopy, magnetometry, computational methods suggest for reduced form electronic structure a ferromagnetically coupled iron(ii) imidyl radical, whereas oxidation leads to mixed iron(iii) electrophilic character. Reactivity studies show that both are capable H atom abstraction from bonds. Further, [Fe(NMes)L2]- reacts nucleophilically CS2 by inserting into bond, electrophilically CO under transfer. The neutral [Fe(NMes)L2] complex shows enhanced behavior evidenced transfer phosphine, yet combination overall reactivity.

Language: Английский

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Open-Shell Early Lanthanide Terminal Imides

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(9), P. 4102 - 4113

Published: Feb. 25, 2022

Group 3- and 4f-element organometallic chemistry reactivity are decisively driven by the rare-earth-metal/lanthanide (Ln) ion size associated electronegativity/ionicity/Lewis acidity criteria. For these reasons, synthesis of terminal "unsupported" imides [Ln═NR] smaller, closed-shell Sc(III), Lu(III), Y(III), increasingly covalent Ce(IV) has involved distinct reaction protocols while derivatives "early" large Ln(III) have remained elusive. Herein, we report such open-shell lanthanide cations Ce(III), Nd(III), Sm(III) according to a new protocol. Lewis-acid-stabilized methylidene complexes [TptBu,MeLn(μ3-CH2){(μ2-Me)MMe2}2] (Ln = Ce, Nd, Sm; M Al, Ga) react with 2,6-diisopropylaniline (H2NAriPr) via methane elimination. The formation arylimide is governed size, Lewis group 13 metal alkyl, steric factors, presence donor solvent, sterics (pKa) aromatic amine. Crucially, arylimides [TptBu,MeLn(═NAriPr)(THF)2] Sm) formed only for Ga, [TptBu,MeLn(NAriPr)(AlMe3)] persistent. In stark contrast, [GaMe3]-stabilized imide [TptBu,MeLn(NAriPr)(GaMe3)] reversibly in noncoordinating solvents.

Language: Английский

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Ti-Catalyzed Modular Ketone Synthesis from Carboxylic Derivatives and gem-Dihaloalkanes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(27), P. 14884 - 14893

Published: June 26, 2023

Ketones are ubiquitous in organic synthesis. However, the general method to convert widely available carboxylic acids, unactivated esters, and amides into ketones remains elusive. Herein, we describe Ti-catalyzed modular ketone synthesis from derivatives easily accessed gem-dihaloalkanes. Notably, this protocol could achieve direct catalytic olefination of acids. This features a sequence electrophilic transformation good functional group compatibility allows rapid access various functionalized ketones. Preliminary mechanistic studies provide insights reaction pathway support intermediacy plausible alkylidene titanocene gem-bimetallic complexes.

Language: Английский

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Ti-Catalyzed and -Mediated Oxidative Amination Reactions

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(17), P. 3476 - 3490

Published: Aug. 23, 2021

ConspectusTitanium is an attractive metal for catalytic reaction development: it earth-abundant, inexpensive, and generally nontoxic. However—like most early transition metals—catalytic redox reactions with Ti are difficult because of the stability high-valent TiIV state. Understanding fundamental mechanisms behind processes key making progress toward potential applications. This Account details recent in Ti-catalyzed (and -mediated) oxidative amination that proceed through formally TiII/TiIV cycles.This class built on our initial discovery [2 + 2 1] pyrrole synthesis from alkynes azobenzene, where detailed mechanistic studies have revealed important factors allow turnover despite inherent difficulty redox. Two conclusions (1) low-valent intermediates catalysis can be stabilized coordination π-acceptor substrates or products, they act as "redox-noninnocent" ligands metal-to-ligand π back-donation, (2) reductive elimination π-type electrocyclic (or pericyclic) rather than direct σ-bond coupling.The reactive species imidos (Ti≡NR), which generated either aryl diazenes (RN═NR) organic azides (RN3). These then undergo 2] cycloadditions alkynes, resulting coupled to array other unsaturated functional groups, including alkenes, nitriles, nitrosos. basic reactivity pattern has been extended into a broad range stoichiometric multicomponent coupling small molecules, leading syntheses various heterocycles aminated building blocks.For example, two different leads pyrroles, while nitriles pyrazoles. heterocycle often yield substitution patterns complementary those classical condensation routes provide access new electron-rich, highly substituted heteroaromatic scaffolds. Furthermore, alkyne carboamination accomplished via yielding α,β-unsaturated imine cyclopropylimine blocks. New methods such α-diimination, isocyanide imination, ring-opening strained alkenes continuously emerging result better understanding catalysis.Ultimately, these -mediated demonstrate importance examining often-overlooked elements like metals lens modern catalysis: lack utility, frequently undiscovered transformations orthogonal selectivity their late counterparts.

Language: Английский

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s‐Block Multiple Bonds: Isolation of a Beryllium Imido Complex

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(17), P. 9407 - 9411

Published: Jan. 10, 2021

Abstract A common feature of d ‐ and p ‐block elements is that they participate in multiple bonding. In contrast, the synthesis compounds containing homo‐ or hetero‐nuclear bonds involving s‐block extremely rare. Herein, we report synthesis, molecular structure, computational analysis a beryllium imido (Be=N) complex ( 2 ), which was prepared via oxidation Be 0 precursor 1 ) with trimethylsilyl azide Me 3 SiN (TMS‐N ). Notably, compound features shortest known Be=N bond (1.464 Å) to date. This represents first an metal‐nitrogen bond. All were characterized experimentally multi‐nuclear NMR spectroscopy H, 13 C, 9 Be) single‐crystal X‐ray diffraction studies. The bonding situation analyzed density functional theory (DFT) calculations, supports existence π‐bonding between nitrogen.

Language: Английский

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Catalytic Carbodiimide Guanylation by a Nucleophilic, High Spin Iron(II) Imido Complex

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(14), P. 5324 - 5329

Published: April 1, 2021

Reduction of the three-coordinate iron(III) imido [Ph2B(tBuIm)2Fe═NDipp] (1) affords [Ph2B(tBuIm)2Fe═NDipp][K(18-C-6)THF2] (2), a rare example high-spin (S = 2) iron(II) complex. Unusually for late metal complex, ligand in 2 has nucleophilic character, as demonstrated by reaction with DippNH2, which establishes an equilibrium bis(anilido) complex [Ph2B(tBuIm)2Fe(NHDipp)2][K(18-C-6)THF2] (3). In unusual transformation, formal insertion iPrN═C═NiPr into Fe═N(imido) bond yields guanidinate [Ph2B(tBuIm)2Fe(iPrN)2CNDipp][K(18-C-6)THF2] (4). Reaction 4 excess DippNH2 provides 3, along guanidine (iPrNH)2C═NDipp. As suggested these stoichiometric reactions, is efficient catalyst guanylation carbodiimides, converting wide range aniline substrates under mild conditions.

Language: Английский

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