Copper(I) complexes of N-alkyl-substituted N-Heterocyclic carbenes

Kuehn, Laura; Eichhorn, Antonius; Marder, Todd B.; Radius, Udo

doi:10.1016/j.jorganchem.2018.11.032

Cited by 23 publications

(19 citation statements)

References 82 publications

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“…The distances between the carbenic carbon atoms and the copper atom in 5c are slightly shorter than those in 5a and 5d.T he CÀCu distances in 5a are similart ot hose of [(Dipp 2 Im) 2 Cu][X] (X = PF 6 :1 .938(5) ; [58] BF 4 :1 .939(18) ; [58] BPh 4 :1 .872(4) ; [62a] Bneop 2 :1.9204( 14) ; [62b] Bpin 2 :1.920(4) ; [62c] (1.898(6)-1.908 (7) ). [63] The C2ÀCu distances in 5c (1.898(2) ) and 5d (1.9136( 14) )a re slightly longer than d(CÀCu) in the related chloride complexes [(Me 2 Im Me )CuCl] (1.878(2) ) [65] and [(cAAC Me )CuCl] (1.878(2) ). [66] The corresponding cationic copperi ons were detected in the high resolution mass spectra of 5a-e (5a: m/z 839.50; 5b: m/z 631.38; 5c: m/z 575.31; 5d: m/z 736.46; 5e: m/z 729.30).…”

Section: Resultsmentioning

confidence: 99%

“…(1.898(6)-1.908(7) ). [63] The C2ÀCu distances in 5c (1.898(2) ) and 5d (1.9136(14) )a re slightly longer than d(CÀCu) in the related chloride complexes [(Me 2 Im Me )CuCl] (1.878(2) ) [65] and [(cAAC Me )CuCl] (1.878(2) ). [66] The corresponding cationic copperi ons were detected in the high resolution mass spectra of 5a-e (5a: m/z 839.50; 5b: m/z 631.38; 5c: m/z 575.31; 5d: m/z 736.46; 5e: m/z 729.30).…”

Section: Nickel Complexesmentioning

confidence: 99%

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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: Resultsmentioning

confidence: 99%

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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“…This outcome may be related to the inherent instability of the respective free carbenes, when containing small alkyl N-substituents, [25][26][27] though accessibility of these free carbenes has been demonstrated. [28][29][30][31] Complex formation was also unsuccessful when applying a one pot synthesis using equimolar quantities of imidazolium salt and Cu(OAc)2 in the presence of tBuOK (1.2 molequiv.) under inert conditions (dry THF, N2 atmosphere).…”

Section: Resultsmentioning

confidence: 99%

Imidazolylidene Cu(II) Complexes: Synthesis Using Imidazolium Carboxylate Precursors and Structure Rearrangement Pathways

et al. 2019

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Copper(II) complexes of type (NHC)CuX2 (X = OAc, Cl, Br, BF4, NO3) bearing monodentate N-heterocyclic carbenes (NHCs) were prepared by in situ decarboxylation of imidazolium carboxylates as a new synthetic methodology for Cu(II)-NHC complexes. In contrast to the classical deprotonation method, the decarboxylation protocol does not require anaerobic conditions and provides access to complexes with NHCs that are unstable as free carbenes such as N,N'-diisopropyl-imidazolylidene and N,N'-dimethyl-imidazolylidene. Spectroscopic evidence of the formation of the Cu-CNHC bond is provided by UV-vis and EPR, in particular by the 44 MHz carbene hyperfine coupling constant using a 13 C-labelled imidazolylidene ligand. A variation of the nature of the carbene N-substituents and the anions bound to the Cu(II) center is possible with this methodology. These variations strongly influence the stability of the complexes. Structural rearrangement and ligand reorganization was observed during recrystallisation, which are comprised of heterolytic Cu-CNHC bond dissociation for unstable NHC ligands as well as homolytic Cu-X bond cleavage and disproportionation reactions depending on the nature of the anion X in the copper complex.

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“…There are only a few examples of similar coordination of copper(I) with NHCs in the literature. 35,36 The Cu center adopts a distorted trigonal geometry in 5, where Cu and I atoms are located at the crystallographic axis of rotation (Figure 5). The silylene moieties are twisted out of the plane, which makes the structure look like a propeller.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…5 is a structurally unique complex due to the coordination of two molecules of 1 to the one copper(I) center. There are only a few examples of similar coordination of copper(I) with NHCs in the literature. , …”

Section: Resultsmentioning

confidence: 99%

Carbazole Substituted Amidinato Silylene: Synthesis, Bonding, and Coordination Behavior with Coinage Metals

2021

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In this work, the synthesis and characterization of a new carbazole substituted amidinatosilylene (1) and its coinage metal complexes 3–8 are being reported. Before the complexation reactions, we prepared [PhC(NtBu)2Si(Cbz)→Co(CO)Cp] complex (2) to estimate the σ-donating strength of the newly synthesized silylene 1. Further, several commonly available coinage metal salts were utilized for the complexation reactions with 1, which afforded complexes 3–8. The solid-state structures of 1–8 have been validated by single-crystal X-ray diffraction studies, NMR spectroscopy, and mass spectroscopy. DFT studies were also performed to understand the bonding scenario of 1 and 3–7. Of note, 1 consists of a HOMO on its carbazolide moiety, and the HOMO-1 features the silylene character. We also compared the HOMO-LUMO gap of 1 with other amidinato silylenes having different N-substitutions.

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Copper(I) complexes of N-alkyl-substituted N-Heterocyclic carbenes

Cited by 23 publications

References 82 publications

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

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

Imidazolylidene Cu(II) Complexes: Synthesis Using Imidazolium Carboxylate Precursors and Structure Rearrangement Pathways

Carbazole Substituted Amidinato Silylene: Synthesis, Bonding, and Coordination Behavior with Coinage Metals

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