Stable Dimer Intermediates during Intercluster Reactions of Atomically Precise Nanoclusters

Abstract

Intercluster reactions involving atomically precise noble metal nanoclusters (NCs) in solution, closely resembling reactions between molecules, are important for exploring chemistry on the nanoscale. In the present study, we conducted reactions between [Ag₂₉(1,3-BDT)₁₂]^3– (1,3-BDT = 1,3-benzenedithiol) and center-doped [MAg₂₄(2,4-DMBT)₁₈]^q− (q = 1 for M = Ag, Au; and q = 2 for M = Pd, Pt; 2,4-DMBT = 2,4-dimethylbenzenethiol) NCs in solution. For the first time, we report the formation of stable dimers, formed between two NCs with mixed metal–ligand interfaces. The dimeric species formed were [MAg_53–xBDT₁₂DMBT_18–y]^3– (x ≥ 0 and y ≥ 0), with 16 electrons in their valence shells. Here, the dimers were formed irrespective of the nature of the central atom in the NC, although the compositions were different depending on the central atom. These dimers were stable in solution for ∼2 days. The dithiol-protected [Ag₂₉BDT₁₂]^3– part was more stable in the dimers, during fragmentation than the monothiol-protected [MAg₂₄DMBT₁₈]^q− part. UV/vis spectroscopic and mass spectrometric analyses, along with density functional theory calculations, were used to understand the dimers. Our work highlighted the importance of the cluster interface in the stability of the dimer formed. Probing such stable dimers formed during intercluster reactions can help us understand the reaction mechanism in greater detail.