The majority of industrial gold recovery techniques rely on 120-year-old cyanidation methods that use large amounts of sodium cyanide, which can potentially have a negative impact on the environment. Alternative approaches that convert the ore to chloroauric or bromoauric acid have attractive features, but also drawbacks that make it hard to recover purified material. This presentation describes a new supramolecular approach that recovers HAuX<sub>4</sub> by co-precipitation using synthetic receptors that are either tetralactam macrocycles or simpler acyclic systems. X-ray crystal structures of the complexes show important supramolecular interactions such as hydrogen bonding between the receptor and the chloride or bromide ligands, and co-facial stacking of the receptor aromatic sidewalls and the gold center. Additionally, unusual proton stabilization was observed. The possibility of exploiting this new supramolecular chemistry for greener gold recovery will be discussed.

New approach to gold recovery: Supramolecular co-precipitation of square-planar gold complexes

2019 Spring National Meeting

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