The X-ray structure of the {Cu(NH3)4[Au(CN)2]}+[Au(CN)2]− salt is reported showing an unprecedented [d9]Cu⋯[d10]Au coinage bond. The physical nature of the interaction has been studied using DFT calculations, including the quantum theory of atoms-in-molecules, the noncovalent interaction plot and the natural bond orbital analysis, revealing the nucleophilic role of the [d10]Au metal and the electrophilic role of [d9]Cu metal.
