Role of Intercluster and Interligand Dynamics of [Ag₂₅(DMBT)₁₈]⁻ Nanoclusters by Multinuclear Magnetic Resonance Spectroscopy

Abstract

Even though gold and silver belong to the same group of the periodic table, they provide significantly different nanocluster (NC) structures in terms of both nuclearities and ligand coordination motifs. Until today, only one isostructural gold analogue has been found for silver nanoclusters, [Ag25(DMBT)18]−, and it is only obtained by using 2,4-dimethylbenzenethiol (DMBT) as the ligand. Our study of the dynamics of DMBT ligands in metal NCs using multinuclear magnetic resonance spectroscopy demonstrates that DMBT favors the formation of two types of interligand interactions, i.e., H−π and π–π. These interactions stabilize the entire nanocluster, yet we observe that thermal and chemical stimuli have the capability to weaken the [Ag25(DMBT)18]− structure triggering irreversible decomposition. Moreover, employing 2D-NMR spectroscopy we demonstrate the intercluster exchange of DMBT ligands and their temperature dependence.