Tellurium compounds, chemical bonding

Chemical Bonding. From the above calculations, it is clear that information on chemical bonding of Te compounds can be inferred from the associated quadrupole splitting data. We have neglected the ionic character of the Te bonds in tellurium. However, this parameter may need to be included in bonding calculations of Te compounds as is done, for example, in the Townes and Dailey approximation. 

The chemical bonding in iodine compounds is much simpler to describe than that in tin, antimony, or tellurium which precede it in the Periodic Table. This is particularly true where the iodine forms only one bond to another atom. As a result it is possible to develop a quantitative interpretation of the Mossbauer parameters. The equations given here were first formulated by Hafemeister et al. [74] and subsequently revised to a more elegant form by Perlow and Perlow [72]. 

Calculations were made of the approximate values of the bond ionicity of ternary alkali antimonides containing oxygen, sulfur, selenium, and tellurium. The dependences were obtained of the nature of the chemical bonding on the positions of the elements (forming these compounds) in the periodic table. 

This review is conceived as a progress report. It includes only compounds of selenium and tellurium with the element directly bonded to fluorine. The chemical literature of the last 10 years, including 1979, has been searched thoroughly, and emphasis has been placed on facts rather than on interpretation. There are some earlier reviews covering the same area "Fluorine Compounds of Selenium and Tellurium 1970 (40), "Inorganic Selenium Chemistry 1975 (48), and "Inorganic Chemistry of Tellurium 1975 (53). 

A final and unusual type of carbon-bonded acetylacetonate is that in which the metal atom forms a derivative at a terminal or 1-carbon. The only compounds in this case are three tellurium derivatives shown in Fig. 1G, H, I. These compounds were first prepared by Morgan and Drew (33) in the 1920 s, and on the basis of chemical evidence they correctly postulated the structure of 1G, but not of 1H or 11. Recent spectroscopic studies by Dewar et al. (34) have confirmed the structure of 1G and determined the structures illustrated in Fig. IH and II. It is interesting to note here that sulfur and selenium form bonds only to the 3-carbon atom. At present it is difficult to rationalize the loss of hydrogen for a terminal methyl group which is many orders of magnitude less reactive than the 3-protons. 

The first two sections of this chapter are the usual ones on (1) the discovery and isolation of the elements and (2) the application of the network to group chemistry. The third section, necessitated by the great ability of sulfur to catenate, concentrates on the allotropes and compounds that involve element-to-element bonds. Next is a short section on the relatively new and potentially useful sulfur nitrides. The reactions and compounds of practical importance in the fourth section include sodium-sulfur batteries, the photoelectric properties of selenium and tellurium, and the most important commercial chemical in the world, sulfuric acid. The selected topic in depth is the production, effects, and possible control of acid rain. 

---