Hypervalent molecule

A hypervalent molecule is a molecule that contains one or more main group elements formally bearing more than eight electrons in their valence shells. Phosphorus pentachloride (PCl₅), sulfur hexafluoride (SF₆), the phosphate (PO₄³⁻) ion, chlorine trifluoride (ClF₃) and the triiodide (I₃⁻) ion are examples of hypervalent molecules.

Definitions and nomenclature

Hypervalent molecules were first formally defined by Jeremy I. Musher in 1969 as molecules having central atoms of group 15-18 in any oxidation state other than the lowest.

Several specific classes of hypervalent molecules exist:

• Hypervalent iodine compounds are useful reagents in organic chemistry (e.g. Dess-Martin periodinane)
• Tetra-, penta- and hexacoordinated phosphorus, silicon, and sulfur compounds (ex. PCl₅, PF₅, SF₆, sulfuranes and persulfuranes)
• Noble gas compounds (ex. xenon tetrafluoride, XeF₄)
• Halogen polyfluorides (ex. ClF₅)
• Non-classical carbocations (ex. Norbornyl cation)
• Many common acids (ex. chloric acid, phosphoric acid, and sulfuric acid)

N-X-L notation

N-X-L nomenclature, introduced in 1980,Perkins,C. W.; Martin, J. C.; Arduengo, A....
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