Cooperative Ligands in Dissolution of Gold. Issue 34 (17th May 2021)

• Record Type: Journal Article
• Authors: Heliövaara, Eeva; Liljeqvist, Henri; Muuronen, Mikko; Eronen, Aleksi; Moslova, Karina; Repo, Timo
• Is Part Of: Chemistry. Volume 27:Issue 34(2021)
• Page Start: 8668
• Page End: 8672
• Publication Date: 2021-05-17
• Subjects: gold -- gold dissolution -- ligand exchange -- reaction mechanisms -- S ligands; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202101028
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Development of new, environmentally benign dissolution methods for metallic gold is driven by needs in the circular economy. Gold is widely used in consumer electronics, but sustainable and selective dissolution methods for Au are scarce. Herein, we describe a quantitative dissolution of gold in organic solution under mild conditions by using hydrogen peroxide as an oxidant. In the dissolution reaction, two thiol ligands, pyridine‐4‐thiol and 2‐mercaptobenzimidazole, work in a cooperative manner. The mechanistic investigations suggest that two pyridine‐4‐thiol molecules form a complex with Au 0 that can be oxidized, whereas the role of inexpensive 2‐mercaptobenzimidazole is to stabilize the formed Au I species through a ligand exchange process. Under optimized conditions, the reaction proceeds vigorously and gold dissolves quantitatively in two hours. The demonstrated ligand‐exchange mechanism with two thiols allows to drastically reduce the thiol consumption and may lead to even more effective gold dissolution methods in the future. Abstract : Dissolution of elemental gold : Gold is dissolved promptly with a combination of two different thiol ligands by ligand‐exchange reaction. Pyridine‐4‐thiol serves as the initiating ligand and 2‐mercaptobenzimidazole ligands stabilize the formed Au I cations in the dissolution.