Enlargement of Globular Silver Alkynide Cluster via Core Transformation

The multinuclear metal-ligand supramolecular synthon R-C C superset of Ag-n (R = alkyl, cycloalkyl; n = 3, 4, 5) has been employed to construct two high-nuclearity silver ethynide cluster compounds, [Cl6Ag8@ Ag-30((BuC)-Bu-t C)(20)(ClO4)(12)]center dot Et2O (1) and [Cl6Ag8@ Ag-30((t)chxC C)(20)(ClO4)(10)](ClO4)(2)center dot 1.5Et(2)O (chx = cyclo-hexyl) (2), that bear the same novel Cl6Ag8 central core. The synthesis of 1 made use of [Cl@Ag-14((BuC)-Bu-t C)(12)]OH as a precursor, and its reaction with AgClO4 in CH2Cl2 resulted in an increase in nuclearity from 14 to 38. The results presented here strongly suggest that the formation of multinuclear silver ethynide cage complexes 1 and 2 proceeds by a reassembly process in solution that involves transformation of the encapsulated chloride template within a Ag-14 cage into a cationic pseudo-O-h Cl6Ag8 inner core, leading to the generation of a much enlarged Cl6Ag8@Ag-30 cluster within a cluster. To our knowledge, this provides the first example of the conversion of a silver cluster into one of higher nuclearity via inner-core transformation.