Gold’s Structural Versatility within Complex Intermetallics: From Hume-Rothery to Zintl and even Quasicrystals

Recent exploratory syntheses of polar intermetallic compounds containing gold have established gold’s tremendous ability to stabilize new phases with diverse and fascinating structural motifs. In particular, Au-rich polar intermetallics contain Au atoms condensed into tetrahedra and diamond-like three-dimensional frameworks. In Au-poor intermetallics, on the other hand, Au atoms tend to segregate, which maximizes the number of Au-heteroatom contacts. Lastly, among polar intermetallics with intermediate Au content, complex networks of icosahedra have emerged, including discovery of the first sodium-containing, Bergman-type, icosahedral quasicrystal. Gold’s behavior in this metal-rich chemistry arises from its various atomic properties, which influence the chemical bonding features of gold with its environment in intermetallic compounds. Thus, the structural versatility of gold and the accessibility of various Au fragments within intermetallics are opening new insights toward elucidating relationships among metal-rich clusters and bulk solids.