Although Cu²⁺ is ubiquitous, the relativistic destabilization of the 5d orbitals makes the isoelectronic Au²⁺ exceedingly rare, typically stabilized only through Au–Au bonding or by using redox non-innocent ligands. Here we report the perovskite Cs₄Au^IIAu^III₂Cl₁₂, an extended solid with mononuclear Au²⁺ sites, which is stable to ambient conditions and characterized by single-crystal X-ray diffraction. The 2+ oxidation state of Au was assigned using ¹⁹⁷Au Mössbauer spectroscopy, electron paramagnetic resonance, and magnetic susceptibility measurements, with comparison to paramagnetic and diamagnetic analogues with Cu²⁺ and Pd²⁺, respectively, as well as to density functional theory calculations. This gold perovskite offers an opportunity to study the optical and electronic transport of the uncommon Au^2+/3+ mixed-valence state and the characteristics of the elusive Au²⁺ ion coordinated to simple ligands. Compared with the perovskite Cs₂Au^IAu^IIICl₆, which has been studied since the 1920s, Cs₄Au^IIAu^III₂Cl₁₂ exhibits a 0.7 eV reduction in optical absorption onset and a 10³-fold increase in electronic conductivity.

尽管 Cu ²⁺无处不在，但 5d 轨道的相对论不稳定使得等电子 Au ²⁺极其罕见，通常只能通过 Au-Au 键合或使用氧化还原非无害配体来稳定。在这里，我们报道了钙钛矿 Cs ₄ Au ^II Au ^III ₂ Cl ₁₂ ，这是一种具有单核 Au ²⁺位点的扩展固体，它在环境条件下稳定，并通过单晶 X 射线衍射进行了表征。使用¹⁹⁷ Au 穆斯堡尔谱、电子顺磁共振和磁化率测量来确定 Au 的 2+ 氧化态，并分别与 Cu ²⁺和 Pd ²⁺的顺磁性和抗磁性类似物进行比较，以及密度泛函理论计算。这种金钙钛矿为研究罕见的 Au ^2+/3+混合价态的光学和电子传输以及与简单配体配位的难以捉摸的 Au ²⁺离子的特性提供了机会。与自1920年代以来研究的钙钛矿Cs ₂ Au ^I Au ^III Cl ₆相比，Cs ₄ Au ^II Au ^III ₂ Cl ₁₂的光学吸收起始点降低了0.7 eV，电子电导率提高了10 ³倍。