Evolution of all-carboxylate-protected superatomic Ag clusters confined in Ti-organic cages

In this study, the size of the titanium organic cage was controlled to achieve the restricted growth from a single Ag(I) atom ( Ag@Ti 5 ) to rare all-carboxylate-protected superatomic Ag cluster ( Ag 6 @Ti 6 ). The classical octahedral Ag 6 4+ cluster with two delocalized electrons (2e) has been encapsulated in a Ti 6 organic cage, which shows high stability in air and dimethyformamide (DMF). Furthermore, larger 2e nested double-tetrahedra Ag clusters (Ag 8 6+ and Ag 9 7+ ) protected using a tetrahedral hollow metalloligand framework ( Ag 8 @Ti 4 and Ag 9 @Ti 4 ) were obtained. Electrospray ionization mass spectrometry (ESI-MS) and density functional theory (DFT) calculations confirmed that there are two delocalized electrons on these small Ag clusters. This study provides a new form of protection for superatomic Ag clusters and provides a feasible strategy for the development of stable Ag clusters.