Group 16 elements oxygen compounds

Supplement to Mellor s Comprehensive Treatise on Inorganic and Theoretical Chemistry , Vol. V, Boron Part A, Boron-Oxygen Compounds , Longman, London, 1980, 825 pp. See also J. R. Bowser and T. P. Fehlner, Chap. 1 in H. W. Roesky (ed.). Rings, Clusters and Polymers of Main Group and Transition Elements, Elsevier, Amsterdam, 1989, pp. 1-48. 

The chalcogenides are binary compounds of a chalcogen (i.e., the elements of Group Ilb zinc, cadmium, mercury) with a less electropositive element, such as those of Group VIb (oxygen, sulfur, selenium, and tellurium). This section covers the sulfides, selenides, andtellurides. Oxides are reviewed above in Ch. 11. Most of the chalcogenides have useful optical characteristics and their applications are usually found in optics. 

Heavier main-group elements like T1(I), in complex compounds, generally exhibit a stereochemically active lone pair when the donor atoms are nitrogen, oxygen or fluorine [23]. 

Until recently only a handful of main group elements — carbon, nitrogen, oxygen and sulfur — were known to be able to form stable (p-p)rc bonds. The complete lack of such bonds in compounds of the heavier elements had been rationalized by theoretical treatments by Pitzer u and Mulliken 2). Indeed, many commonly used textbooks of inorganic chemistry contain statements such as,. . p-p-n bonding is of little importance in the third and higher period elements,3). 

The constant x depends on the class of compound (e.g., aromatic vs. aliphatic), ry is the number of specific atoms (e.g., C or Cl), y is a constant specific to that atom and how it is bonded, rij is the number of certain bonds or structural types (e.g., double or triple bonds or branching), and z is a constant specific to these bonds or structural elements. Lyman et al. (1982) gives a full account of this approach and recommend it as the preferred method when no partition coefficient data are available. However, this method is dated and does not include functional groups containing oxygen, nitrogen, and sulfur atoms. 

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