Stabilizing Au2+ in a mixed-valence 3D halide perovskite

Kurt P Lindquist; Armin Eghdami; Christina R Deschene; Alexander J Heyer; Jiajia Wen; Alexander G Smith; Edward I Solomon; Young S Lee; Jeffrey B Neaton; Dominic H Ryan; Hemamala I Karunadasa

doi:10.1038/s41557-023-01305-y

Stabilizing Au²⁺ in a mixed-valence 3D halide perovskite

Nat Chem. 2023 Dec;15(12):1780-1786. doi: 10.1038/s41557-023-01305-y. Epub 2023 Aug 28.

Authors

Kurt P Lindquist¹, Armin Eghdami², Christina R Deschene¹, Alexander J Heyer¹, Jiajia Wen³, Alexander G Smith², Edward I Solomon^{1

4}, Young S Lee^{3

5}, Jeffrey B Neaton^{2

6

7}, Dominic H Ryan⁸, Hemamala I Karunadasa^{9

10}

Affiliations

¹ Department of Chemistry, Stanford University, Stanford, CA, USA.
² Department of Physics, University of California Berkeley, Berkeley, CA, USA.
³ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
⁴ Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA.
⁵ Department of Applied Physics, Stanford University, Stanford, CA, USA.
⁶ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁷ Kavli Energy NanoSciences Institute at Berkeley, Berkeley, CA, USA.
⁸ Physics Department and Centre for the Physics of Materials, McGill University, Montreal, Quebec, Canada.
⁹ Department of Chemistry, Stanford University, Stanford, CA, USA. hemamala@stanford.edu.
¹⁰ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA. hemamala@stanford.edu.

PMID: 37640854
DOI: 10.1038/s41557-023-01305-y

Abstract

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.

Abstract

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