What determines if a ligand activates or passivates a superatom cluster?

Area of Science:

• * Nanoscale science and materials chemistry.
• * Quantum effects in small metal clusters.
• * Superatom chemistry and electronic shell structure.

Background:

• * Quantum confinement in small metal clusters creates electronic shells, analogous to atomic shells, enabling superatom classification.
• * Ligands are used to tune valence electron counts and protect metal cluster cores from etching.
• * The interplay between ligands and metal cores is crucial for cluster stability and reactivity.

Purpose of the Study:

• * To investigate the reactivity of methanol with iodine-ligated aluminum clusters.
• * To understand how ligands influence the stability and etching of metal clusters.
• * To elucidate the role of Lewis acid/base sites in cluster reactivity.

Main Methods:

• * Joint experimental and theoretical investigation.
• * Study of methanol reactivity with aluminum clusters ligated with iodine.
• * Analysis of electronic structure and active site formation.

Main Results:

• * Ligands can enhance cluster stability but may also create active sites for etching due to charge density perturbations.
• * Reactivity is governed by Lewis acid and Lewis base active sites formed by ligand positioning and aluminum core structure.
• * Observed etching of aluminum clusters by methanol, driven by specific ligand-cluster interactions.

Conclusions:

• * Ligand effects on metal cluster stability are complex, with potential for both protection and destabilization.
• * The positioning of electronegative ligands significantly impacts cluster reactivity by creating active sites.
• * This research provides insights into the stability of ligand-protected clusters synthesized via wet chemistry.