摘要:

A new internal coordinate, referred to as Keating's bending, is defined in terms of the familiar R vectors.

ISSN:0038-7010    

DOI:10.1080/00387018408062709

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The harmonic force field of theE' species of BF3is studied. The Keating force field (KFF) is defined in analogy with the familiar VFF and CFF. In this connection three different coordinate sets are introduced. All of them contain bond stretchings. In addition, the valence coordinates include ordinary (Decius') bendings, the central coordinates nonbond stretchings, and Keating coordinates the Keating's bendings.

ISSN:0038-7010    

DOI:10.1080/00387018408062710

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The experimental works of vibrational spectroscopy and normal coordinate analyses for BCl3, BBr3and BI3are reviewed extensively. Harmonic force fields of theE' species are produced using isotopic frequencies and Coriolis constants as additional data, respectively. The usefulness of Keating coordinates versus valence coordinates as basis of force field approximations is discussed. The conclusions are not unequivocal, but they go in favour of the Keating coordinates when the reliability of the different computations is taken into account. Boron trichloride is treated specifically in some detail. Final force fields are proposed for the title molecules with the aid of the mass influence on Coriolis constants.

ISSN:0038-7010    

DOI:10.1080/00387018408062711

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

TheE' block of the mean-square amplitude matrix (Σ) for the planar symmetrical XY3molecular model is treated theoretically in terms of the Keating coordinates. A numerical example for11BF3is given. Also the mean amplitudes of vibration (ι) and Bastiansen-Morino shrinkage effect (Δ) are considered. New relations which connect the mean-square amplitudes and force constants are given. Previous works on mean amplitudes and related quantities for boron trihalides from vibrational spectroscopy and gas electron diffraction are reviewed, and some new calculations are reported.

ISSN:0038-7010    

DOI:10.1080/00387018408062712

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Force fields from literature for the degenerate (E') vibrations of AlCl3and SO3are transferred from the valence symmetry coordinates to the central- and Keating symmetry coordinates. In both cases it is found |F12k| > |F12| > |F12c|.

ISSN:0038-7010    

DOI:10.1080/00387018408062713

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

TheA1molecular vibrations of the bent symmetrical XY2model are considered. A generalized bending, Ω, is defined in such a way that the (i) ordinary (Decius') bending, (ii) Keating's bending, (iii) the nonbonded (Urey-Bradley-type) stretching and (iv) symmetrical bond stretching all become special cases of it. The force constant denotedF12(Ω) is of interest as a function of Ω. In the numerical example of H2O,F12(Ω)= 0 holds for Ω = 107.2°, which is not far from the interbond equilibrium angle, 2A= 104.53°. This is consistent withF12k≈ 0, where the force constant pertains to the Keating coordinates. In the same connection one finds the KFF (Keating force field) to be superior to the VFF (valence force field) as well as CFF (central force field). Some numerical results are also given for NO2, 03, SO2, ClO2, FlO2, Cl2O and Cl2S. In these cases no general conclusion can be drawn with regard to the superiority of the different coordinate types. As an appendix some explicit formulas are given for the mean amplitudes of vibration (ι) and perpendicular amplitude correction coefficients (K) of the considered molecular model. Numerical values of ι andKfor water are reported.

ISSN:0038-7010    

DOI:10.1080/00387018408062714

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

An approximate force field was deduced for the in-plane vibrations of naphthalene in terms of five parameters corresponding to the coordinates: C-C and C-H stretchings, CCC (two types) and CCH Keating's bendings. Calculated frequencies were compared to observed data. On the other hand, these results were compared to those where Decius' bendings were applied. The set with Keating's bendings proved to be the superior one.

ISSN:0038-7010    

DOI:10.1080/00387018408062715

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In-plane vibrational frequencies of five condensed aromatics were computed from a five-parameter force field pertaining to stretchings and Keating's bendings. The molecules are: anthracene, phenanthrene, pyrene, chrysene and coronene. The results were compared with previous ones from a five-parameter approximation, which employs Decius' bendings. As far as the agreement between calculated and observed frequencies are concerned the results with Keating's bendings appeared clearly to be the superior ones in all the cases investigated.

ISSN:0038-7010    

DOI:10.1080/00387018408062716

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Symmetry coordinates were developed for the dodecaborane-ion type X12Y12model of symmetryIh.Two sets of force constants for the ion are reported, where it was made use of Decius' and Keating's bendings, respectively. Calculated frequencies for B12H12and B12D12are compared with observed data. Better agreement was obtained for the set with Keating's bendings. This conclusion is consistent with one of a previous normal coordinate analysis.

ISSN:0038-7010    

DOI:10.1080/00387018408062717

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0038-7010    

DOI:10.1080/00387018408062708

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor