Gold as a 6p-Element in Dense Lithium Aurides

• Published in: Journal of the American Chemical Society 2016-03, Vol.138 (12), p.4046-4052
• Main Authors: Yang, Guochun, Wang, Yanchao, Peng, Feng, Bergara, Aitor, Ma, Yanming
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.5b11768

The negative oxidation state of gold (Au) has drawn a great attention due to its unusual valence state that induces exotic properties in its compounds, including ferroelectricity and electronic polarization. Although monatomic anionic gold (Au–) has been reported, a higher negative oxidation state of Au has not been observed yet. Here we propose that high pressure becomes a controllable method for preparing high negative oxidation state of Au through its reaction with lithium. First-principles calculations in combination with swarm structural searches disclosed chemical reactions between Au and Li at high pressure, where stable Li-rich aurides with unexpected stoichiometries (e.g., Li4Au and Li5Au) emerge. These compounds exhibit intriguing structural features like Au-centered polyhedrons and a graphene-like Li sublattice, where each Au gains more than one electron donated by Li and acts as a 6p-element. The high negative oxidation state of Au has also been achieved through its reactions with other alkali metals (e.g., Cs) under pressures. Our work provides a useful strategy for achieving diverse Au anions.