N-heterocyclic silylene stabilized monocordinated copper(<scp>i</scp>)–arene cationic complexes and their application in click chemistry

Parvin, Nasrina; Hossain, Jabed; George, Anjana; Parameswaran, Pattiyil; Khan, Shabana

doi:10.1039/c9cc09115g

Cited by 25 publications

(11 citation statements)

References 35 publications

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“…Consequently, in both 4 and 5f the aryl ligand can be substituted by other donors, which wasa lso previously observed for the related complex [(Dipp 2 Im)Cu(toluene)][SbF 6 ]. [67] However,f luoride abstraction with af luoride-ion acceptors uch as (C 2 F 5 ) 3 PF 2 is advantageousc ompared to bromidea bstraction with as ilver salt of aW CA, since 1) it is am ore atom-efficient process, 2) the Lewis acid (C 2 F 5 ) 3 PF 2 is cheaper than silver salts of WCAs, and 3) it is not necessary to remove any byproducts uch as AgBr.…”

Section: Nickel Complexesmentioning

confidence: 99%

Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry

Föhrenbacher

Krahfuß

Zapf

et al. 2021

Chemistry A European J

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Fluoride abstraction from different types of transition metal fluoride complexes [LnMF] (M=Ti, Ni, Cu) by the Lewis acid tris(pentafluoroethyl)difluorophosphorane (C2F5)3PF2 to yield cationic transition metal complexes with the tris(pentafluoroethyl)trifluorophosphate counterion (FAP anion, [(C2F5)3PF3]−) is reported. (C2F5)3PF2 reacted with trans‐[Ni(iPr2Im)2(ArF)F] (iPr2Im=1,3‐diisopropylimidazolin‐2‐ylidene; ArF=C6F5, 1 a; 4‐CF3‐C6F4, 1 b; 4‐C6F5‐C6F4, 1 c) through fluoride transfer to form the complex salts trans‐[Ni(iPr2Im)2(solv)(ArF)]FAP (2 a‐c[solv]; solv=Et2O, CH2Cl2, THF) depending on the reaction medium. In the presence of stronger Lewis bases such as carbenes or PPh3, solvent coordination was suppressed and the complexes trans‐[Ni(iPr2Im)2(PPh3)(C6F5)]FAP (trans‐2 a[PPh3]) and cis‐[Ni(iPr2Im)2(Dipp2Im)(C6F5)]FAP (cis‐2 a[Dipp2Im]) (Dipp2Im=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) were isolated. Fluoride abstraction from [(Dipp2Im)CuF] (3) in CH2Cl2 or 1,2‐difluorobenzene led to the isolation of [{(Dipp2Im)Cu}2]2+2 FAP− (4). Subsequent reaction of 4 with PPh3 and different carbenes resulted in the complexes [(Dipp2Im)Cu(LB)]FAP (5 a–e, LB=Lewis base). In the presence of C6Me6, fluoride transfer afforded [(Dipp2Im)Cu(C6Me6)]FAP (5 f), which serves as a source of [(Dipp2Im)Cu)]+. Fluoride abstraction of [Cp2TiF2] (7) resulted in the formation of dinuclear [FCp2Ti(μ‐F)TiCp2F]FAP (8) (Cp=η5‐C5H5) with one terminal fluoride ligand at each titanium atom and an additional bridging fluoride ligand.

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Section: Nickel Complexesmentioning

confidence: 99%

Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry

Föhrenbacher

Krahfuß

Zapf

et al. 2021

Chemistry A European J

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“…We note that Cu(I) complexes are known to readily access a digonal geometry. 35,[41][42][43][44][45][46][47]48 Indeed, density functional theory (DFT) calculations performed on representative molecular subunits reveal that there is a slight energetic preference for the digonal 1•[CuCl]unlocked over the trigonal planar 1•[CuCl] species (~5 kJ/mol). However, for the analogous Br and I species, the trigonal planar coordination is thermodynamically favoured (Figures S7, S8).…”

Section: •[Cucl]mentioning

confidence: 99%

“…2 (linear), 3 (trigonal planar) and 4 (tetrahedral) are known) 34 that can be interconverted under carefully controlled conditions. 30,35 In addition, we recently demonstrated that 1 can support both tetrahedral and trigonal planar geometries for Cu(I). 30 Thus, we speculated whether a flexible MOF material could be realised by modulating the Cu(I) coordination geometry, i.e.…”

Section: Introductionmentioning

confidence: 96%

Coordination modulated on-off switching of flexibility in a metal–organic framework

et al. 2021

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“…in industry as well as in academia. Thus, after the independent selective synthesis of 1,4-disubstituted triazoles by Sharpless–Fokin and Meldal using Cu(I) compounds as catalysts, considerable attention has been given to the CuAAC reaction. − It has been observed that any Cu(I) source may act as a catalyst for the CuAAC reaction. , Generally, an easily available Cu(II) source like CuSO 4 by the chemical reduction of sodium l -ascorbate was used to generate the Cu(I) catalyst . However, this type of Cu source is not desirable because the Cu(I) oxidation state is very unstable; it may disproportionate to Cu(0) and Cu(II) or may get oxidized to its Cu(II) compound. ,, Thus, a larger quantity of Cu(II) compound is required for the selective synthesis of triazoles .…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in electronics and biomedicine applications, removal of copper ions is a problem. , It has been shown that ancillary ligand coordinated Cu(I) complexes can decrease the catalyst loading and increase the selectivity of the CuAAC reaction, as these Cu(I) complexes are more stable. ,, Employing this strategy, Astruc et al have reported amphiphilic and dendrimer nanoreactors, Uozumi et al have reported amphiphilic self-assembled polymers, Zimmerman et al have reported a metal–organic nanoparticles for parts-per-million (ppm) Cu(I) catalysis in water. However, though a library of Cu(I) complex catalyzed CuAAC reaction is known, − such catalysis in water at a low ppm catalyst loading is still rare. − As Cu(I) is the lower oxidation state of copper, it is important to use a strong π-acceptor-type chelating ligand for the development efficient catalyst for CuAAC reactions. Here, we report a series of amine-functionalized azo-aromatic copper(II) complexes (Scheme A) that showed interesting ligand hemilability upon reduction, and the reduced Cu(I) complexes are highly efficient (up to low ppm level catalysis) for selective CuAAC reaction via intramolecular acid–base cooperation solely in water under air (Scheme B).…”

Section: Introductionmentioning

confidence: 99%

Azide–Alkyne “Click” Reaction in Water Using Parts-Per-Million Amine-Functionalized Azoaromatic Cu(I) Complex as Catalyst: Effect of the Amine Side Arm

et al. 2021

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A series of Cu(II) complexes, 1−4 and 6, were synthesized through a reaction of amine-functionalized pincer-like ligands, HL 1,2 , L a,b , and a bidentate ligand L 1 with CuCl 2 •2H 2 O. The chemical reduction of complex 1 using 1 equiv of sodium Lascorbate resulted in a dimeric Cu(I) complex 5 in excellent yield. All of the complexes, 1−6, were thoroughly characterized using various physicochemical characterization techniques, single-crystal X-ray structure determination, and density functional theory calculations. Ligands HL 1,2 and L a,b behaved as tridentated donors by the coordination of the amine side arm in their respective Cu(II) complexes, and the amine side arm remained as a pendant in Cu(I) complexes. All of these complexes (1−6) were explored for copper(I)-catalyzed 1,3-dipolar azide−alkyne cycloaddition (CuAAC) reaction at room temperature in water under air. Complex 5 directly served as an active catalyst; however, complexes 1−4 and 6 required 1 equiv of sodium L-ascorbate to generate their corresponding active Cu(I) catalyst. It has been observed that azobased ligand-containing Cu(I)-complexes are air-stable and were highly efficient for the CuAAC reaction. The amine side arm in the ligand backbone has a dramatic role in accelerating the reaction rate. Mechanistic investigations showed that the alkyne C−H deprotonation was the rate-limiting step and the pendant amine side arm intramolecularly served as a base for Cu-coordinated alkyne deprotonation, leading to the azide−alkyne 2 + 3 cycloaddition reaction. Thus, variation of the amine side arm in complexes 1−4 and use of the most basic diisopropyl amine moiety in complex 4 has resulted in an unique amine-functionalized azoaromatic Cu(I) system for CuAAC reaction upon sodium L-ascorbate reduction. The complex 4 has shown excellent catalysis at its low partsper-million level loading in water. The catalytic protocol was versatile and exhibited very good functional group tolerance. It was also employed efficiently to synthesize a number of useful functional triazoles having medicinal, catalytic, and targeting properties.

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N-heterocyclic silylene stabilized monocordinated copper(i)–arene cationic complexes and their application in click chemistry

Abstract: Herein, we report N-heterocyclic silylene and N-heterocyclic carbene supported monocoordinated cationic Cu(i) complexes with unsymmetrical arenes (toluene and m-xylene], their reactivity and catalytic application in CuAAC reactions.

Cited by 25 publications

References 35 publications

Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry

Tris(pentafluoroethyl)difluorophosphorane: A Versatile Fluoride Acceptor for Transition Metal Chemistry

Coordination modulated on-off switching of flexibility in a metal–organic framework

Azide–Alkyne “Click” Reaction in Water Using Parts-Per-Million Amine-Functionalized Azoaromatic Cu(I) Complex as Catalyst: Effect of the Amine Side Arm

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