摘要:

Two-centre overlap integrals are evaluated for any combination ofs, p, d, f, gandhorbitals for some low value of the parametern, from which formulae for any higher value ofncan be obtained by simple derivation. The formulae are well suited for desk calculations.

ISSN:0026-8976    

DOI:10.1080/00268976200100111

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The electron spin resonance spectra of CH3ĊH(CO2H) inγ-irradiatedα-alanine between 100°kand 200°kdiffer from the spectra obtained above and below this range. The ‘intermediate temperature’ spectra are interpreted in terms of a rather critical rate of rotation of the methyl group. From the line-width change near 100°kand 200°kan estimate of approximately 4 kcals has been made for the activation energy hindering the rotation of the methyl group.

ISSN:0026-8976    

DOI:10.1080/00268976200100121

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

This paper describes a semi-emprical quantitative theory of the low-lying electronic states of the radicals CH, CH2, CH3, NH, NH2, BH, BH2and BH3. The method combines certain features of the valence-bond theory and Moffitt's method of Atoms in Molecules, and bond bending is taken into account. The results are in excellent general agreement with experiment: the ground state of CH2is a linear3Σg-state, whose potential energy curve crosses that of the lowest singlet state which is bent. The CH3radical is predicted to resist out-of-plane deformation quite strongly, and the BH2radical is predicted to be linear in its ground state.

ISSN:0026-8976    

DOI:10.1080/00268976200100131

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The chemical shifts of the proton resonances in dimethyl formamide, diethyl formamide and dimethyl acetamide have been measured as a function of concentration in 31 solvents. The shifts extrapolated to infinite dilution are discussed in terms of complex formation between the amide and aromatic solvents.

ISSN:0026-8976    

DOI:10.1080/00268976200100141

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

Shifts in the proton resonances of mesityl oxide,β,β-dimethyl acrylic acid, acetoxime,γ-picoline and N, N dimethyl phosphoramidic dichloride are given for solutions of these substances in various solvents. The differential shifts of the resonances in aromatic solvents are interpreted in terms of stereo-specific association.

ISSN:0026-8976    

DOI:10.1080/00268976200100151

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The e.s.r. spectrum of the durosemiquinone cation exhibits a marked line width alternation effect which is dependent on the temperature and the solvent. The effect is ascribed to cis-trans isomerism, the lifetime of each isomer being comparable with the inverse frequency separation between the proton hyperfine components.

ISSN:0026-8976    

DOI:10.1080/00268976200100161

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The crystal spectra of copper acetylacetonate first measured by Ferguson are re-interpreted using the results of an accurate crystal structure determination. The principles involved in such an analysis are fully discussed. The analysis does not provide unambiguous assignments of the observed bands because of the unfortunate orientation of the molecule in unit cell and also because it is not known which vibrations are effective in promoting the transitions. Therefore, there is now no reason to discard the ground state assignment based on the crystal field theory and results of electron spin resonance. The spectral data in solutions is reviewed and tentative assignments of the bands are proposed.

ISSN:0026-8976    

DOI:10.1080/00268976200100171

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The method of double irradiation has been used to determine the relative signs of all the F-F (and H-F) spin coupling constants in three trifluorethylene derivatives. In all three cases,JFFtransis of opposite sign toJFFcisandJFFgem.

ISSN:0026-8976    

DOI:10.1080/00268976200100181

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The first three absorption bands of CO2-trapped in crystalline sodium formate have been detected and their intensities and directions of polarization determined. The spectrum is similar to that theoretically calculated by Green and Linnett [10] for NO2apart from a large shift to higher energies. In addition the first absorption band of HCO2-has been shown to be polarized parallel to the O … O direction in this ion.

ISSN:0026-8976    

DOI:10.1080/00268976200100191

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor

摘要:

The proton resonance spectra of trans hydroxy-L-proline and allo hydroxy-L-proline in D2O are obtained and completely analysed to give the coupling constants between, and chemical shifts of, all the non-exchangeable protons in the molecules. The values of the coupling constants between protons on adjacent carbon atoms in the five-membered ring vary from 1 to 10 c.p.s. Also a long-range coupling over four bonds is observed between one C3proton and one C5proton in both compounds. From the values of the proton-proton couplings, it is proposed that the ring in both compounds is considerably buckled in solution. The ring in the trans hydroxy proline has a conformation in which C4projects out of the plane of the other ring atoms in the opposite direction to the carboxyl group. In the allo compound no such simple conformation is found.

ISSN:0026-8976    

DOI:10.1080/00268976200100201

出版商:Taylor & Francis Group    

年代:1962

数据来源: Taylor