Intermolecular =C–H···:C hydrogen bond in a crystalline unsaturated Arduengo-type carbene

Leites, L. A.; Magdanurov, Gaidar I.; Bukalov, S. S.; West, Robert

doi:10.1016/j.mencom.2008.01.006

Cited by 15 publications

(13 citation statements)

References 27 publications

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“…First, DFT modeling the interaction of cation [(nIDipp) 2 Zn-Me] + (IV)w ith free IDipp (Carb)l ed to the exergonic formation of cation A (DG = À14.3 kcal mol À1 , Figure 7), which features aC ÀH· ·· Chydrogen-bond interaction between IDipp (C2) and one IDipp ligand in cation IV.T hough 4 + and IDipp do not apparently interacti ns olution ( 1 HNMR, C 6 D 5 Br,r oom temperature), NHCs are well-knowns trong Hbond acceptors owing to their Brønsted basicity and the acidic character of NHCÀC4/C5ÀH hydrogen atoms is also exemplified. [20,21] Besides H-bonding, dispersive interactions in A (between the incoming IDipp ligand and IV)c ertainly favor itss tabilization,asdeduced from computed noncovalentinteractions for A ( Figure S28',S upporting Information). H-bonded IDipp in cation A is ideally disposed for deprotonation of aC 4 ÀH Scheme3.Isomerization of cation [D 4 ]4 + to [D 4 ]5 + .…”

Section: Resultsmentioning

confidence: 99%

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

Specklin

Fliedel

Gourlaouen

et al. 2017

Chemistry A European J

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Tri-organyl and tricoordinate N-heterocyclic carbene (NHC) Zn-NHC alkyl cations [(nNHC) Zn-Me] (nNHC=C2-bonded-IMes/-IDipp; 3 and 4 ; IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were first synthesized and structurally characterized by ionization of the corresponding neutral precursors [(nNHC)ZnMe ] with [Ph C][B(C F ) ] in the presence of one equivalent of free NHC. Whereas cation [(nIMes) Zn-Me] (3 ) is stable, its sterically congested analogue [(nIDipp) Zn-Me] (4 ) readily undergoes an nNHC-to-aNHC isomerization in the presence of THF or IDipp to afford the more thermodynamically stable [(aIDipp)(nIDipp)Zn-Me] (aIDipp=C4-bonded IDipp, 5 ), reflecting the adaptable-to-sterics coordination chemistry of these cations for improved stability. Cations 3 -5 are the first Zn cations of the type Zn(C)(C')(C'') (C, C', C''=σ-donor carbyl ligand). Kinetic studies combined with DFT calculations agree with an nNHC-to-aNHC process proceeding through the initial deprotonation of 4 (at a Zn-bonded C4-IDipp moiety) by IDipp. Unlike 3 and 4 , the rearranged cation 5 reacts with CO through insertion into the Zn-Me bond yielding the corresponding Zn(κ -OAc) cation 6 . Both cations 5 and 6 were successfully used in CO hydrosilylation catalysis for silylformate formation.

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Section: Resultsmentioning

confidence: 99%

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

Specklin

Fliedel

Gourlaouen

et al. 2017

Chemistry A European J

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“…The multiplicity of both the H-4 and H-5 signals also changes,f rom tripletb efore electrolysis to doublet (part II of Figure 2). [51,52] The 1 HNMR spectrar eveal that electrolysis of [BMIm][NTf 2 ] generates new diamagnetic speciesi nt he cathodic compartment. All these observations reveal the presence of carbene 3.…”

Section: Resultsmentioning

confidence: 99%

“…The apparent rate constant characterizing the exchange of H-2 between the BMIm + cation 1 and carbene 3 is proportional to the concentration of 3;i tt husi ncreases for increasing concen-trations of carbene and this is consistentwitht he narrowing of the H-2 signal observedf or longere lectrolysis duration.T his degenerate protone xchange might involve ab is(carbene)protonc omplexa si ntermediate, which exhibits unusualhydrogen bonds previously characterised by X-ray crystallography. [51,52] The 1 HNMR spectrar eveal that electrolysis of [BMIm][NTf 2 ] generates new diamagnetic speciesi nt he cathodic compartment. Structure elucidation of these compounds has proven to be challenging.…”

Section: Resultsmentioning

confidence: 99%

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

et al. 2017

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Potential controlled electrolyses of [BMIm][NTf ] ionic liquid were performed at a gold cathode under nitrogen atmosphere. The structures of the major conversion products of the BMIm cation were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) analyses and gas chromatography (GC) analysis of the volatile compounds. Recombination of the imidazol-2-yl radicals, generated at the electrode by single electron transfer, leads to neutral diastereomeric dimers in equal proportions, with a faradaic efficiency of 80 %, while disproportionation of these radicals and/or reaction with hydrogen atoms adsorbed at the electrode generates a neutral monomer with 20 % faradaic efficiency. Both pathways also yield the N-heterocyclic carbene imidazolin-2-ylidene, which is involved in fast proton exchange with the parent BMIm cation. The reductive decomposition products of the BMIm cation are no longer detected if the pre-electrolysed sample is reacted with CO , which undergoes an indirect reduction and generates the carboxylate adduct.

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“…The presence of hydrogen bonds involving the “abnormal” C−H can be observed for 12 , 13 , 25 , and 26 . Owing to the lack of structural information for ILs in general, this feature is difficult to judge, however, it is closely related to findings for abnormal hydrogen bonding in NHCs …”

Section: Resultsmentioning

confidence: 99%

Calorimetric Studies and Structural Aspects of Ionic Liquids in Designing Sorption Materials for Thermal Energy Storage

Brünig

Krekić

Bruhn

et al. 2016

Chemistry A European J

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The thermal properties of a series of twenty‐four ionic liquids (ILs) have been determined by isothermal titration calorimetry (ITC) with the aim of simulating processes involving water sorption. For eleven water‐free ILs, the molecular structures have been determined by X‐ray crystallography in the solid state, which have been used to derive the molecular volumes of the ionic components of the ILs. Moreover, the structures reveal a high prevalence of hydrogen bonding in these compounds. A relationship between the molecular volumes and the experimentally determined energies of dilution could be established. The highest energies of dilution observed in this series were obtained for the acetate‐based ILs, which underlines their potential as working fluids in sorption‐based thermal energy storage systems.

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Intermolecular =C–H···:C hydrogen bond in a crystalline unsaturated Arduengo-type carbene

Cited by 15 publications

References 27 publications

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

Calorimetric Studies and Structural Aspects of Ionic Liquids in Designing Sorption Materials for Thermal Energy Storage

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Intermolecular =C–H···:C hydrogen bond in a crystalline unsaturated Arduengo-type carbene

Cited by 15 publications

References 27 publications

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO2 Functionalization

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO2 Functionalization

NMR Study of the Reductive Decomposition of [BMIm][NTf2] at Gold Electrodes and Indirect Electrochemical Conversion of CO2

Calorimetric Studies and Structural Aspects of Ionic Liquids in Designing Sorption Materials for Thermal Energy Storage

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N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

N‐Heterocyclic Carbene Based Tri‐organyl‐Zn–Alkyl Cations: Synthesis, Structures, and Use in CO₂ Functionalization

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂