Enlargement of Globular Silver Alkynide Cluster via Core Transformation

The multinuclear metal–ligand supramolecular synthon R–CC⊃Ag_n (R = alkyl, cycloalkyl; n = 3, 4, 5) has been employed to construct two high-nuclearity silver ethynide cluster compounds, [Cl₆Ag₈@Ag₃₀(^tBuCC)₂₀(ClO₄)₁₂]·Et₂O (1) and [Cl₆Ag₈@Ag₃₀(chxCC)₂₀(ClO₄)₁₀]­(ClO₄)₂·1.5Et₂O (chx = cyclohexyl) (2), that bear the same novel Cl₆Ag₈ central core. The synthesis of 1 made use of [Cl@Ag₁₄(^tBuC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 Ag₁₄ cage into a cationic pseudo-O_h Cl₆Ag₈ inner core, leading to the generation of a much enlarged Cl₆Ag₈@Ag₃₀ 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.