Zintl isoelectronic relationships

This chapter examines Zintl isoelectronic relationships. The chapter starts by noting how many binary compounds are formed between the Group 1 and 2 elements and Groups 13–15. The Zintl concept utilizes isoelectronic relationships in order to provide some insight into the solid state structures adopted by such compounds. The chapter highlights that the electronegativity differences between the atoms are sufficiently large in these compounds that, to a first approximation, an ionic formulation is reasonable. The isoelectronic relationship is then used as a basis for rationalizing the manner in which the Group 13–15 elements aggregate in the solid state. Next, the chapter explains that many of the anionic species observed in Zintl phases in the solid state are not observed as stable solution species. This is because their large negative charges make them very nucleophilic and therefore sensitive to the slightest traces of moisture.