Dissociation, Chemical Exchange, and the Proton Magnetic Resonance in Some Aqueous Electrolytes

Gutowsky, H. S.; Saika, A.

doi:10.1063/1.1698644

Cited by 514 publications

(161 citation statements)

References 15 publications

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“…In both these ions, though oppositely charged, the protons are less screened relative to Hz0 by 10-11 p.p.m. (21,22). T o account for this it has been proposed (23) that only the square term in eq.…”

Section: For Benzene Itself This Gives a Contribution T O The Proton mentioning

confidence: 99%

Proton Magnetic Resonance Shifts and the Electron Density Distribution in Aromatic Systems

Schaefer¹,

Schneider²

1963

Can. J. Chem.

235

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The quantitative nature of the empirical linear correlation between the proton resonance shifts in aromatic molecules and the local electron density on the carbon atom to which the proton is bonded has been investigated. The application of this relationship t o the determination of the electron density distribution of a variety of aromatic molecules, as well as the main limitations inherent in this application, are discussed. Electron density distributions have been derived for aniline, anisole, azulene, acepleiadylene, pyridine, pyridinium ion, and for the aromatic ions pentalenyl, indenyl, fluorenyl, triphenylmethyl cation, and azulene dianion, and are compared with those calculated by molecular orbital methods. In general there is a fairly good correspondence between the experimental and calculated density values, although for the aromatic ions the excess charge tends t o be somewhat more uniformly distributed over the molecule than would be indicated by simple MO calculations.

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Section: For Benzene Itself This Gives a Contribution T O The Proton mentioning

confidence: 99%

Proton Magnetic Resonance Shifts and the Electron Density Distribution in Aromatic Systems

Schaefer¹,

Schneider²

1963

Can. J. Chem.

235

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“…Since the beginning of the application of NMR in chemistry it has been used for quantitative determination of reaction rate constants [1][2][3][4]. The theory and reams of examples for exchange rate measurements by NMR can be found in books [5][6][7][8] review articles [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Ligand exchange and complex formation kinetics studied by NMR exemplified on fac-[(CO)3M(H2O)]+ (M=Mn, Tc, Re)

Helm

2008

Coordination Chemistry Reviews

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“…spectra was recognized in the original work of Gutowsky et al (2,6), and various approximate analytical expressions have been developed to derive kinetic data for specific cases (7-10). Only recently, how-…”

Section: Introductionmentioning

confidence: 99%

Nuclear Magnetic Resonance Studies of Multi-site Chemical Exchange. II. Hindered Rotation in N,N-Dimethyl Carbamyl Fluoride

Reeves¹,

Shaw²

1971

Can. J. Chem.

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The matrix formulation of the Bloch equations including chemical exchange reported earlier is extended to include indirect spin-spin coupling in first-order spectra. The ABX (JAB = 0) spin system is treated in detail and particular attention is paid to the determining effect on the nuclear magnetic resonance (n.rn.r.) lineshapes of the relative signs of the coupling constants J A X and J B X . The hindered rotation for N,N-dimethyl carbamyl fluoride in CCI4 as solvent has been studied using a complete lH n.m.r. lineshape analysis and the activation parameters obtained are: AG* = 18.1 + 0.6 kcal rnol-l, AH* = 17.7 + 0.6 kcal rnol-', and AS* = -1.4 + 2.1 cal deg-' mol-' at 25 "C. Introductionever, have complete lineshape analyses been The Bloch equations (1) have been modified to applied to multi-site exchange systems with include chemical exchange effects (2-4), in first-J-coupling (1 1-15). Inconsistent analyses are still order spectra, and have allowed a simple phe-appearing in the literature, however, and very nomenological description of n.m.r. lineshape little reliable kinetic data is available. Thus this characteristics. In the first paper in this series ( 5 ) , paper outlines the inclusion of J-coupling for the a concise matrix formulation of the modified representative ABX (JAB = 0) spin system. It is Bloch equations has been presented as a basis shown that, from a complete lineshape analysis for a series of experimental studies of a wide range of chemical systems. This formulation accommodates a general first-order n-site exchange system and a complete description of all rate processes is contained in a single n x n matrix. Such a theoretical approach allows an efficient routine analysis for rate constants and activation parameters.The effect of chemical exchange on spin-spin multiplets in first-order n.m.r. spectra was recognized in the original work of Gutowsky et al. (2,6), and various approximate analytical expressions have been developed to derive kinetic data for specific cases (7-10). Only recently, how-

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Dissociation, Chemical Exchange, and the Proton Magnetic Resonance in Some Aqueous Electrolytes

Cited by 514 publications

References 15 publications

Proton Magnetic Resonance Shifts and the Electron Density Distribution in Aromatic Systems

Proton Magnetic Resonance Shifts and the Electron Density Distribution in Aromatic Systems

Ligand exchange and complex formation kinetics studied by NMR exemplified on fac-[(CO)3M(H2O)]+ (M=Mn, Tc, Re)

Nuclear Magnetic Resonance Studies of Multi-site Chemical Exchange. II. Hindered Rotation in N,N-Dimethyl Carbamyl Fluoride

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