Penetrated Ion Pairs: a New Form of Ion Pair

Abstract

Ion pairs whose van der Waals volume is smaller than the sum of the volumes of the single ions were discovered recently. The picture on the right shows an example of these penetrated ion pairs. Here a BF ion penetrates the empty spaces between the alkyl chains of a tetrabutylammonium ion. It has now become possible to study and explain the structures and interactions of ion pairs in solution with NMR techniques.