摘要:

The electron spin resonance spectrum of the pyrogallol semiquinone radical has been measured in aqueous solutions of varying pH, a rapid flow system being employed for production of the radicals. Distinct spectra are obtained from species possessing two, one and zero hydroxyl protons and the first and second acid dissociation constants of the pyrogallol radical cation are estimated. It is possible to set upper limits on the rate of hydroxyl proton exchange between the radical species and the solvent.

ISSN:0026-8976    

DOI:10.1080/00268976400100131

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The classical configurational free-energy of a system of molecules with steep intermolecular potentials is obtained from that of a system of hard spheres by an expansion in powers ofn-1, wherenis a measure of the steepness of the potential. It is shown that the free energy can be obtained explicitly and exactly to the order ofn-1. Higher terms have non-thermodynamic coefficients. The first-order term yields an excellent equation of state for gases at high temperatures and densities. It can also be used to calculate the course of the melting line of monatomic close-packed solids at high pressures in terms of the parameters of the repulsive potential. It is shown, subject only to the neglect of terms of the order ofn-2, that there is no solid-fluid critical point for molecules with continuous but steep repulsive potentials.

ISSN:0026-8976    

DOI:10.1080/00268976400100141

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The electron spin resonance spectrum of the fluorenone anion has been measured in mixtures of an alcohol with dimethylformamide. The main dependence of the proton coupling constants on the concentration of alcohol may be understood in terms of an equilibrium between the solvated ketyl and a ketyl-alcohol hydrogen-bonded complex, but a secondary solvent effect must be postulated to account completely for the variation. The changes in spin density in the ketyl on formation of the ketyl-alcohol complexcannotbe understood using simple Hückel molecular-orbital theory.

ISSN:0026-8976    

DOI:10.1080/00268976400100151

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The factors which determine the electron resonance line widths of transition metal complexes in solution are considered. For complex ions possessing two or more unpaired electrons the dominant relaxation mechanism arises from coupling of the zero-field splitting of the spin multiplet with the random tumbling of the molecules in fluid solution. The theory of this effect is re-examined using the time-dependent density matrix methods of Redfield.

ISSN:0026-8976    

DOI:10.1080/00268976400100161

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Several workers have attempted to correlate19F chemical shifts in fluorinated benzene derivatives with theπ-electron charge densities and bond orders as calculated by the Hückel molecular orbital method. In all cases chemical shifts of the fluorine nuclei in meta and para positions to substituents could be predicted successfully, but for fluorine nuclei at ortho positions large deviations were encountered. We have shown that such ortho effects in haloperfluorobenzenes can be accounted for satisfactorily in terms of intramolecular electric field contributions.

ISSN:0026-8976    

DOI:10.1080/00268976400100171

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Calculations have been made using the alternant molecular orbitals (AMO) proposed by Löwdin, which are designed to make some allowance for correlation effects arising from interelectron repulsion, for the electrons in theπ-systems of the allyl radical and ions. Calculations have also been carried out at the same general level of approximation using a full configuration interaction (CI) treatment and the non-paired spatial orbitals first used by Hirst and Linnett. It is found that the function using non-paired spatial orbitals resembles the full CI one more closely than does the AMO function. This conclusion is based on the calculation of energies and overlap integrals.

ISSN:0026-8976    

DOI:10.1080/00268976400100181

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Bei allen Verfahren der Quantenchemie, in denen die Wellenfunktion als Summe von Determinanten dargestellt wird, treten bei Verwendung von Slater- oder slaterähnlichen Funktionen grosse Intergrationsschwierigkeiten auf. Diese können praktisch beseitigt werden, wenn sogenannte reine Gaußfunktionen verwendet werden. Es handelt sich dabei um Funktionen vom Typ

ISSN:0026-8976    

DOI:10.1080/00268976400100191

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Experimental results are given for both the steady-state proton magnetic resonance line shape and for the echo amplitude modulation pattern for liquid methyl alcohol over a temperature range which includes the collapse of theJmultiplet due to increasingly rapid hydroxyl proton exchange.

ISSN:0026-8976    

DOI:10.1080/00268976400100201

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976400100211

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976400100221

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor