Electrostatic Field Model Research Articles

A vanished substituent effect predicted by the Kirkwood-Westheimer electrostatic field model

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA vanished substituent effect predicted by the Kirkwood-Westheimer electrostatic field modelCharles T. Wang and Edward J. GrubbsCite this: J. Org. Chem. 1977, 42, 3, 534–536Publication Date (Print):February 1, 1977Publication History Published online1 May 2002Published inissue 1 February 1977https://doi.org/10.1021/jo00423a030RIGHTS & PERMISSIONSArticle Views57Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (406 KB) Get e-Alerts Get e-Alerts

Analysis of the behavior ofEr3+in zircon-structure systems

New sets of crystal-field parameters have been derived for ${\mathrm{Er}}^{3+}$ in YAs${\mathrm{O}}_{4}$, YP${\mathrm{O}}_{4}$, YV${\mathrm{O}}_{4}$, and ScV${\mathrm{O}}_{4}$ crystals, which give a simultaneous good account for the ground-level $g$ values, the hyperfine interaction constants, and susceptibility in addition to the observed Stark levels. Moreover, calculations of the anisotropy and quadrupole splitting for these systems are included. The old as well as new sets of crystal-field parameters are discussed in the framework of electrostatic crystal field, angular overlap, and superposition models. The ionic bonding is found to decrease in the order (YAs${\mathrm{O}}_{4}$, YP${\mathrm{O}}_{4}$), YV${\mathrm{O}}_{4}$, ScV${\mathrm{O}}_{4}$. An attempt has also been made to estimate the spin-lattice relaxation time. Furthermore, based on the analysis of the observed spectroscopic splitting factors and hyperfine interaction constants, crystal-field parameters are reported for ${\mathrm{Er}}^{3+}$ in ZrSi${\mathrm{O}}_{4}$, HfSi${\mathrm{O}}_{4}$, and ThSi${\mathrm{O}}_{4}$.

Ligand-Field Treatment of the Jahn—Teller Distortion in VCl4

A ligand-field treatment of the Jahn—Teller distortion in VCl4 is developed using perturbation methods. Several of the results are at variance with those obtained earlier by means of the electrostatic crystal field model, and are in substantial agreement with some recent molecular orbital calculations. It is found that distortions are of the same order of magnitude as the relevant zero-point vibrational energies so that no ``static'' effect can be expected. This is in accordance with the available experimental evidence. Our results suggest certain splittings in the infrared and Raman spectrum of VCl4. On the basis of the present experimental evidence the consequences of such a ``dynamic'' Jahn—Teller effect can neither be confirmed nor contradicted with certainty.

Do the ``Ligand Field'' Parameters in Lanthanides Represent Weak Covalent Bonding?

Instead of explaining the seven different f-orbital energies or five different d-orbital energies by parameters Anm〈rn〉 of the electrostatic ligand field model, we propose to classify the energy levels according to the actual one-electron energies and to interpret these quantities by the weak effects of σ antibonding on the partly filled shell. Calculations of the relative angular dependence Ξ2 of such effects are made in a simple model and compared with experimental data for nine- and eight-coordinated lanthanide compounds. The agreement is judged to be much more satisfactory than when the electrostatic model is applied, and the number of freely chosen parameters is much smaller.

Some examples of different spectroscopic and magnetic properties connected with the chromium III — oxygen bond

The spectra are given of some chromium (III) complexes in while the chromium atom has oxygen as the six nearest neighbours. The ligand field parameter Δ is found to vary remarkably much and in a way different from what would be expected in view of the electrostatic ligand field model. Some unexpected spectroscopic and magnetic phenomena with polynuclear complexes are described.