Book excerpt: Seven chapters report current research into the phases and ions of a class of compounds that are electronically positioned between the intermetallic compounds and insulating valence compounds. They cover structure and bonding at the Zintl border, structural patterns of homo- and hetero-nuclear anions and related intermetallic compounds and concepts for interpreting them, the early p-block elements, polyanions in liquid ionic alloys, molecular transition metal complexes, transition metal compounds, and synthesizing and characterizing intermetallic materials using Zintl phases as precursors. An introduction surveys the life and work of German chemist Eduard Zintl (1898-1941). Annotation copyright by Book News, Inc., Portland, OR