Selective gold precipitation by a tertiary diamide driven by thermodynamic control

DOI: 10.1021/acs.inorgchem.4c01279

Authors: Susanna S. M. Vance (University of Edinburgh) , Mateusz Mojsak (University of Edinburgh) , Luke M. M. Kinsman (University of Edinburgh) , Rebecca Rae (University of Edinburgh) , Caroline Kirk (University of Edinburgh) , Jason B. Love (University of Edinburgh, Diamond Light Source) , Carole A. Morrison (University of Edinburgh)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry , VOL 15

State: Published (Approved)
Published: May 2024
Diamond Proposal Number(s): 29800

Abstract: The simple diamide ligand L was previously shown to selectively precipitate gold from acidic solutions typical of e-waste leach streams, with precipitation of gallium, iron, tin, and platinum possible under more forcing conditions. Herein, we report direct competition experiments to afford the order of selectivity. Thermal analysis indicates that the gold-, gallium-, and iron-containing precipitates present as the most thermodynamically stable structures at room temperature, while the tin-containing structure does not. Computational modeling established that the precipitation process is thermodynamically driven, with ion exchange calculations matching the observed experimental selectivity ordering. Calculations also show that the stretched ligand conformation seen in the X-ray crystal structure of the gold-containing precipitate is more strained than in the structures of the other metal precipitates, indicating that intermolecular interactions likely dictate the selectivity ordering. This was confirmed through a combination of Hirshfeld, noncovalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) analyses, which highlight favorable halogen···halogen contacts between metalates and pseudo-anagostic C–H···metal interactions in the crystal structure of the gold-containing precipitate.

Subject Areas: Chemistry


Instruments: I11-High Resolution Powder Diffraction

Added On: 13/05/2024 08:09

Documents:
vance-et-al-2024-selective-gold-precipitation-by-a-tertiary-diamide-driven-by-thermodynamic-control.pdf

Discipline Tags:

Physical Chemistry Chemistry Inorganic Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction