Jahn–Teller effects in Au₂₅(SR)₁₈

Abstract

The relationship between oxidation state, structure, and magnetism in many molecules is well described by first-order Jahn-Teller distortions. This relationship is not yet well defined for ligated nanoclusters and nanoparticles, especially the nano-technologically relevant gold-thiolate protected metal clusters. Here we interrogate the relationships between structure, magnetism, and oxidation state for the three stable oxidation states, -1, 0 and +1 of the thiolate protected nanocluster Au₂₅(SR)₁₈. We present the single crystal X-ray structures of the previously undetermined charge state Au₂₅(SR)₁₈⁺¹, as well as a higher quality single crystal structure of the neutral compound Au₂₅(SR)₁₈⁰. Structural data combined with SQUID magnetometry and DFT theory enable a complete description of the optical and magnetic properties of Au₂₅(SR)₁₈ in the three oxidation states. In aggregate the data suggests a first-order Jahn-Teller distortion in this compound. The high quality single crystal X-ray structure enables an analysis of the ligand-ligand and ligand-cluster packing interactions that underlie single-crystal formation in thiolate protected metal clusters.