Hypervalent bond, definition

The main purpose of this chapter is to review the development of hypervalent chalcogen chemistry after the book of "Chemistry of Hypervalent Compounds edited by Akiba (1999).5 Although several types of compounds may belong to hypervalent ions or molecules by the definition,3a such hypervalent chalcogen compounds (E = S, Se, and Te) will be mainly discussed here that contain CT-type linear bonds.15... 

ICI3, and SeCLi were first reported almost two centuries ago, appropriate models to describe the bonding in these molecnles have only been developed recently. Whilst the term hypervalent is widely nsed and often misnsed there is currently no universally accepted definition of the word. Thus, it is instmctive briefly to explain the origin of the term before giving the working definition for this article. 

The definition of hypervalent species as ions or molecules of the elements of Groups 15—18 bearing more than eight electrons within a valence shell was proposed byj. I. Musherin 1969 (1969AGE54). General aspects of bonding... 

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