To achieve dimer formation based on complexation, it is essential to introduce Fe(BF4)2 only into the system, while maintaining the structure of the BB cluster. To suppress the occurrence of the aforementioned ligand exchange during mixing, [BF4] -was consistently used as a counteranion of the precursor Au13 cluster (e.g., 1•(BF4)3 and 20-1•(BF4)3). In the experiment, the addition of NaBF4 to an ethanol solution of 1•(Cl -)3 induced counteranion exchange and changes in the solubility of the cluster, resulting in the precipitation of 1•(BF4 -)3 (Fig. )).