Dipole moments and complexation enthalpies of 1-methyl and 1,2-dimethylimidazole with various phenols in benzene solution. Angle between the moment of the bases and the hydrogen bond

Huyskens, P.; Cleuren, W. C.; Franz, Małgorzata; Vuylsteke, M. A.

doi:10.1021/j100458a016

Cited by 23 publications

(4 citation statements)

References 2 publications

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“…The addition of a large excess of (BimH) 3 to a Cu· 8 mixture did not change the characteristic yellow color or electronic spectrum of the neocuproine complex; the Cu(I)· (BimH) 3 complex is colorless. To the extent that protic basicity is correlated with binding affinity (and for Cu(I), such a correlation is likely to be only partially valid), triazoles (p K a of conjugate acid ≈ 0.1−1.0) are expected to be the poorest binders, followed closely by benzothiazoles (p K a ≈ 1.2), and then by pyridines (p K a ≈ 5.2) and benzimidazoles (p K a ≈ 6.3). , All of these heterocycles are kinetically labile on Cu(I).…”

Section: Resultsmentioning

confidence: 99%

“…To the extent that protic basicity is correlated with binding affinity (and for Cu(I), such a correlation is likely to be only partially valid 10 ), triazoles (pK a of conjugate acid ≈ 0.1-1.0) 11 are expected to be the poorest binders, followed closely by benzothiazoles (pK a ≈ 1.2), 12 and then by pyridines (pK a ≈ 5.2) and benzimidazoles (pK a ≈ 6.3). 13,14 All of these heterocycles are kinetically labile on Cu-(I).…”

Section: Resultsmentioning

confidence: 99%

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Ligand-Accelerated Cu-Catalyzed Azide−Alkyne Cycloaddition: A Mechanistic Report

et al. 2007

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The experimental rate law for the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction was found to vary in complex ways with concentration, the presence of chloride ion, and the presence of accelerating ligands. Several examples of discontinuous ("threshold behavior") kinetics were observed, along with a decidedly nonlinear correlation of electronic substituent parameter with the rate of CuAAC reaction with p-substituted arylazides. The previously observed tendency of the CuAAC reaction to provide ditriazoles from a conformationally constrained 1,3-diazide was found to be affected by a class of polybenzimidazole ligands introduced in the accompanying article. Various lines of evidence suggest that the standard tris(triazolylmethyl)amine ligand binds less strongly to Cu(I) than its benzimidazole analogues. On the basis of these observations, it is proposed that (a) a central nitrogen donor provides electron density at Cu(I) that assists the cycloaddition reaction, (b) the three-armed motif bearing relatively weakly coordinating heterocyclic ligands serves to bind the metal with sufficient strength while providing access to necessary coordination site(s), (c) at least two active catalysts or mechanisms are operative under the conditions studied, and (d) pendant acid or ester arms in the proper position can assist the reaction by speeding the protiolysis step that cleaves the Cu-C bond of a Cu.triazolyl intermediate.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Ligand-Accelerated Cu-Catalyzed Azide−Alkyne Cycloaddition: A Mechanistic Report

et al. 2007

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“… a Where references to both CGC and literature values and can be found; tw: this work. b Key: B, benzene; C, CCl 4 c Average of two or more runs. d Reference e See run 7 in the Supporting Information. …”

Section: Discussion Of Resultsmentioning

confidence: 99%

The Vaporization Enthalpies of 2- and 4-(N,N-Dimethylamino)pyridine, 1,5-Diazabicyclo[4.3.0]non-5-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene, Imidazo[1,2-a]pyridine and 1,2,4-Triazolo[1,5-a]pyrimidine by Correlation–Gas Chromatography

et al. 2011

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The vaporization enthalpies of a series of heterocyclic compounds some suspected of showing evidence of a higher degree of self-association in comparison to many other nitrogen heterocycles have been measured both by correlation gas chromatography (CGC) and for comparison by transpiration. The compounds share some structural similarities. They include 2- and 4-(N,N-dimethylamino)pyridine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,2,4-triazolo[1,5-a]pyrimidine and imidazo[1,2-a]pyridine. The vaporization enthalpies of the first three of the compounds are well reproduced by a standard series of reference compounds, mainly pyridine derivatives. The latter two compounds and 4-(N,N-dimethylamino)pyridine exhibit vaporization enthalpies approximately 7 kJ·mol(-1) larger. Their values are reproduced by using standards previously shown to exhibit stronger but similar self-association properties. The crystal structure of 1,2,4-triazolo[1,5-a]pyrimidine has been determined in an effort to understand the nature of the self-association. The molecule crystallizes in planar stacks slightly offset with a stacking distance of 3.24 Å.

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“…The conditions when Δp K N = 0 can be treated as critical are when the proton occupies either one broad minimum or is equally distributed between the donor and acceptor atoms. One should also note that the critical point is also well-reflected in the plot of Δ H (enthalpy of H-bond formation) versus Δp K N …”

Section: Nature Variety Of Appearance and Properties Associated With ...mentioning

confidence: 90%

Interrelation between H-Bond and Pi-Electron Delocalization

2005

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Dipole moments and complexation enthalpies of 1-methyl and 1,2-dimethylimidazole with various phenols in benzene solution. Angle between the moment of the bases and the hydrogen bond

Cited by 23 publications

References 2 publications

Ligand-Accelerated Cu-Catalyzed Azide−Alkyne Cycloaddition: A Mechanistic Report

Ligand-Accelerated Cu-Catalyzed Azide−Alkyne Cycloaddition: A Mechanistic Report

The Vaporization Enthalpies of 2- and 4-(N,N-Dimethylamino)pyridine, 1,5-Diazabicyclo[4.3.0]non-5-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene, Imidazo[1,2-a]pyridine and 1,2,4-Triazolo[1,5-a]pyrimidine by Correlation–Gas Chromatography

Interrelation between H-Bond and Pi-Electron Delocalization

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