摘要:

The relative polarizations of the absorption bands in the electronic spectra of the mono- and di-negative ions of biphenyl, terphenyl and quaterphenyl were determined by the same method as reported in a previous paper [1].

ISSN:0026-8976    

DOI:10.1080/00268976300100761

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The 60 Mc/s proton resonance spectrum of 3-chloromercurifuran has been studied and analysed to yield all the proton chemical shifts and the proton-proton and mercury-proton coupling constants. The relative signs of these coupling constants have been determined either by the spin decoupling method or by analysis and it has been shown that all the proton-proton couplings are of the same sign, as are all the mercury-proton ones. The relative signs of the proton-proton and mercury-proton types of coupling constants have not been determined.

ISSN:0026-8976    

DOI:10.1080/00268976300100771

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Absorption spectra of solutions in acetonitrile of tetra (ethyl) ammonium salts of UCl6--, UBr6--, UI6--, NpCl6--, NpBr6--, PuCl6--and PuBr6--show three types of bands arranged according to increasing half-width: (1) internal 5fqtransitions showing a large nephelauxetic effect, the wavenumbers in the hexabromides being some 3–5 per cent smaller than of the corresponding hexachlorides; (2) 5fq→5fq-16d transitions indicating that the 5f→6d orbital energy differences are roughly constant as function ofqin contrast to the strong increase in the aqua ions; (3)π245fq→π235fq+1electron transfer bands indicating that the optical electronegativitiesxopt(corrected for spin-pairing energy and certain effects ofL, S, Jsplitting) are 1·5 for U(IV), 1·75 for Np(IV) and 2·05 for Pu(IV). Further on, the charge separation effects on electron transfer bands are discussed with special regard to uranyl iodide complexes.

ISSN:0026-8976    

DOI:10.1080/00268976300100781

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The radical trapped in x-irradiated monofluoracetamide is shown to be CHF CONH2by electron spin resonance studies. The principal values of the hydrogen hyperfine coupling are -96, -63 and -31 Mc/s and of the fluorine coupling are +530, -11 and -45 Mc/s. The relative signs of the principal couplings were established, using a spectrometer operating at 35 000 Mc/s which is briefly described. The differences in spectra between measurements at 9000 Mc/s and at 35 000 Mc/s are indicated. Finally the couplings are interpreted and shown to be consistent with Hückel parameters for fluorine with (αF-αC) = 2·4βC-F.

ISSN:0026-8976    

DOI:10.1080/00268976300100791

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

In a nuclear magnetic resonance spectrum of the type AMX, the relative signs of the spin coupling constantsJAMandJMXcannot be determined by double resonance experiments ifJAXis unobservably small or zero, but the problem can be solved by the simultaneous application of three radio-frequency fields. This technique is described and demonstrated, and it is suggested that it should prove particularly useful for relating the signs of long-range spin coupling constants to couplings of known sign. Applied to the molecule of 3-bromothiophene-2-aldehyde, this experiment establishes that the long-range coupling to the aldehyde proton has the same sign as the vicinal coupling.

ISSN:0026-8976    

DOI:10.1080/00268976300100801

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The action ofγ-rays on 2-furoic acid is shown, by means of electron spin resonance spectroscopy, to give, in low yield, a radical formed by the addition of a hydrogen atom at position 5. The hyperfine couplings are shown to be in accord with the expected electronic structure for this radical with a negative spin population at C3.

ISSN:0026-8976    

DOI:10.1080/00268976300100811

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The ring proton and fluorine nuclear magnetic resonance spectra of para fluoro acetophenone, para fluoro ethyl benzoate and para fluoro benzonitrile have been studied as an A2B2X system at 40 Mc/sec and 56·445 Mc/sec. As the AB chemical shift is large, the secular equation has been solved in the first approximation. The two meta H-H coupling constants are found to be different. With the values obtained in the first approximation the roots of the involved 4 × 4 determinants have been calculated by an iteration method and it has been found that the values of the parameters are not affected appreciably by the approximation.

ISSN:0026-8976    

DOI:10.1080/00268976300100821

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The ring proton and fluorine nuclear magnetic resonance spectra ofp-fluoronitrobenzene,p-fluorobenzoyl chloride andp-fluorobenzene sulphonyl chloride have been studied as an A2B2X system at 40 and 56·445 Mc/sec. The involved spin coupling constants and chemical shifts are determined.

ISSN:0026-8976    

DOI:10.1080/00268976300100831

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Measurements have been made from a temperature between 14 and 20°kto ∼300°kof the heat capacity of three carbon monoxide quinol clathrates, two oxygen quinol clathrates and one nitrogen quinol clathrate. The results have been used to estimate the contributionCAmade to the heat capacity by a mole of carbon monoxide, nitrogen or oxygen in the clathrate. Analysis of theCAvalues leads to the conclusion that the barrier hindering rotation of the molecules in the cavities is ∼200 cal mole-1for oxygen, ∼1100 cal mole-1for nitrogen and slightly larger for carbon monoxide than for nitrogen. Possible reasons for these differences are briefly discussed. An attempt has been made to calculate the heat capacity contribution of the trapped molecules at low temperatures where a classical treatment is no longer applicable. The agreement with experiment is not good, which may be due party to the alteration of the heat capacity of the lattice itself by the trapped molecules, and partly to the inadequacy of the potential energy function used in the calculations.

ISSN:0026-8976    

DOI:10.1080/00268976300100841

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976300100851

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor