Interparticle Reactions between Silver Nanoclusters Leading to Product Cocrystals by Selective Cocrystallization

We present an example of an interparticle reaction between atomically precise nanoclusters (NCs) of the same metal, resulting in entirely different clusters. In detail, the clusters [Ag₁₂(TBT)₈(TFA)₅(CH₃CN)]⁺ (TBT = tert-butylthiolate, TFA = trifluoroacetate, CH₃CN = acetonitrile) and [Ag₁₈(TPP)₁₀H₁₆]²⁺ (TPP = triphenylphosphine) abbreviated as Ag₁₂ and Ag₁₈, respectively, react leading to [Ag₁₆(TBT)₈(TFA)₇(CH₃CN)₃Cl]⁺ and [Ag₁₇(TBT)₈(TFA)₇(CH₃CN)₃Cl]⁺, abbreviated as Ag₁₆ and Ag₁₇, respectively. The two product NCs crystallize together as both possess the same metal chalcogenolate shell, composed of Ag₁₆S₈, making them indistinguishable. The occupancies of Ag₁₆ and Ag₁₇ are 66.66 and 33.33%, respectively, in a single crystal. Electrospray ionization mass spectrometry (ESI MS) of the reaction product and a dissolved crystal show the population of Ag₁₆ and Ag₁₇ NCs to be in a 1:1 and 2:1 ratio, respectively. This suggests selective crystallization in the cocrystal. Time-dependent ESI MS was employed to understand the formation of product clusters by monitoring the reaction intermediates formed in the course of the reaction. We present an unprecedented growth mechanism for the formation of silver NCs mediated by silver thiolate intermediates.