摘要:

There has been considerable interest recently in the study of the submillimetre (or very far-infrared) absorption shown by both polar1–4and non-polar molecules.2,5–8Such absorption, in the ∼5–100 cm−1region, for non-polar molecules is thought2,6to be caused by fluctuating dipoles associated with classical quadrupole-induced dipole interactions (in general multipole-induced dipole interactions). These effects are said to be “collision-induced” and can be thought of as being due to “collision” complexes in the liquid phase. For polar molecules the absorption is now thought1–4to be due to libration of the dipole in a “cage” of surrounding molecules (either molecules of the same species or of solvent). This so-called Poley-Hill model9,10is not inconsistent with the idea1,2of a residual rotation of the molecular dipole in the liquid phase. This similarity is underlined by the fact that some simple polar molecules11,12have a liquid phase Poley-Hill absorption the general shape and position of which follow quite closely that of the pressure broadened, gas phase spectrum. Our interest in the far-infrared region stems from our studies on halogen complexes with various n and bπ donors.13,14The pyridine-I2system (in cyclohexane) for example shows two bands in the far in frared not present in either component. The band at -183 cm is thought to be the stretching mode of the iodine, perturbed in the complex. The band at ∼96 cm to the v(1-I) band, has so far been interpreted molecular″ stretching modebetween donor and acceptor, v(D-A).

ISSN:0038-7010    

DOI:10.1080/00387017208064952

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Several recent reviews1–3have emphasised the current interest in the study of infrared band shapes in condensed phases. Potentially such data can provide very valuable information4–7about the nature of the rotational and translational motions of individual molecules and about the intermolecular forces between them.7However, because of the possible ambiguities arising in the interpretation of such data, (for example, there may be several contributions to the overall band shape7c,d) it is clear that detailed studies on simple, symmetrical molecules are required before studies on more complex systems are attempted. This has been generally recognised and a number of simple (mostly linear and symmetric top) molecules have now been studied4–10in the compressed gas, liquid and solution phases. We have started a systematic study of simple nitriles and their weak molecular complexes. We report here some interesting data for the symmetric top molecule acetonitrile in the pure liquid and in solution in the “inert” solvent carbon tetrachloride. As far as we are aware the only previous work published on rotational diffusion in acetonitrile is the magnetic resonance work of Bopp.11

ISSN:0038-7010    

DOI:10.1080/00387017208064953

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Recently several rare earth chelates have been found that induce large and dramatic chemical shifts when complexed with a ligand.1This is due to paramagnetic shielding, the mechanism of which is observed to be a pseudo-contact shift. In cases such as this involving dynamic equilibria where exchange of protons is rapid compared to observation time, the observed chemical shift represents an average environment determined by the time the proton nuclei spend at each site. The effective site of the complex is a lone pair donor such as the oxygen of a carbonyl group, alcohol, or ether, or the nitrogen of various nitrogen containing groups. The oxygen bearing compounds could theoretically form strong complexes with the added possibility of multiple complexes with chelates. The nitrogen bearing compounds of weak donor strength and containing only a lone pair would presumably form only the 1:1 complex.

ISSN:0038-7010    

DOI:10.1080/00387017208064954

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The significance and role of outer-sphere interactions for the chemistry of complex compounds and solutions have been discussed in the literature time and again.1,2The existence of the complexesper sein solutions is determined not only by the interactions of the central ion with the near-by ligands, but also with the particles of the outer or secondary coordination sphere. Now, while “intra-sphere” complexes may be both labile and inert with respect to their kinetic behavior in solutions, outer-sphere compounds are predominantly labile. Inasmuch as the majority of outer-sphere compounds cannot be isolated from solutions, NMR-spectroscopy is essentially one of the most convenient methods for their study. Naturally, such investigations are complicated by an exchange of particles constituting associate compositions, and this exchange may be sufficiently rapid to present interest in itself.

ISSN:0038-7010    

DOI:10.1080/00387017208064955

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The definition of the limit of determination in emission spectroscopy is discussed. This is a value derived from the function expressing the final relative precision of concentration determination in dependence on gradually decreasing concentration value.

ISSN:0038-7010    

DOI:10.1080/00387017208064956

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The definition of the final precision value of concentration determination at emission spectroscopy is discused. A method of succesive summing up of partial errors, taking into consideration as well the errors yielded at calibration functions construction, is sugested.

ISSN:0038-7010    

DOI:10.1080/00387017208064957

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0038-7010    

DOI:10.1080/00387017208064951

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor