Precise Implantation of an Archimedean Ag@Cu12 Cuboctahedron into a Platonic Cu4Bis(diphenylphosphino)hexane6 Tetrahedron

Precision loading of nanoclusters in confined spaces, which has been enthusiastically pursued in the scientific realm, is still associated with some mysteries of how, when, and why. Here, we isolated two similar heterometallic cluster-in-cage compounds, [Ag@Cu12S8@Cu-4(dpph)(6)]X (X = OH, SD/AgCu16a and X = PF6, SD/AgCul6b; SD = SunDi), by use of an antigalvanic reaction between organometallic [PhC=CCu](n) and Ph3CSH with elemental silver. Both compounds are formed by fitting an Archimedean Ag@Cu-12 cuboctahedral cluster into a Platonic Cu-4(dpph)(6) tetrahedral cage [dpph = bis(diphenylphosphino)-hexane]. The Ag@Cu-12 cluster is a hollow cuboctahedral Cu-12 cage filled with a central Ag-I atom, and all eight triangular faces of the Ag@Cu-12 cuboctahedron are triply capped by eight S2- ions, four of which in a tetrahedral array further internally pillar four Cu vertices of the outer Cu-4(dpph)(6) tetrahedron, fixing the cluster in the cage. Both compounds can be deemed as molecular fragments excised from porous nanomaterials filled with discrete nanoclusters, thus providing more details for understanding the confined growth of atomically precise nanoclusters. Electrospray ionization mass spectrometry (ESI-MS) reveals that the AgCu16 cluster is quite stable in CH2Cl2 and can stepwise lose dpph ligand in the gas phase under increased collision energy. This work not only presents a precise aggregation of metal atoms in a confined cavity to form a cluster-in-cage compound but also provides deep insights into the binding and geometry matching between clusters and cages in one entity.

Automated summary

The study isolated two similar heterometallic cluster-in-cage compounds through an antigalvanic reaction, providing more details for understanding the confined growth of atomically precise nanoclusters. The compounds can be deemed as molecular fragments excised from porous nanomaterials filled with discrete nanoclusters, shedding light on the binding and geometry matching between clusters and cages.