sentences:  He suggested that the structures of Zintl phases were ionic, where there was complete electron transfer from the more electropositive metal.The structure of the anion (nowadays called the Zintl ion) should then be considered on the basis of the resulting electronic state.These ideas were further developed to become the Zintl rule or Zintl Klemm concept, where the polyanion structure should be similar to an isoelectronic element.