Research results on "metavalent bonding" are discussed in the current edition of "Science"
Chemical bonding is important for understanding and designing new functional materials. In two papers, Wuttig et al. and Raty et al. propose a bonding type they term “metavalent.” Metavalent materials lie between covalently and metallically bound ones but are distinctly different from both. Several of the compounds that plot in the metavalent field have unique and important physical properties that make for good thermoelectric, phase-change, and other functional materials. The new bonding category potentially provides a guide for the development of interesting new materials.