Atom-by-atom substitution is a promising strategy for designing new cluster-based materials, which has been used to generate new gold- and silver-containing clusters. Here, the first study focused on atom-by-atom substitution of Fe and Ni to the core of a well-defined cobalt sulfide superatom [Co6 S8 L6 ]+ ligated with triethylphosphine (L = PEt3 ) to produce [Co5 MS8 L6 ]+ (M = Fe, Ni) is reported. Electrospray ionization mass spectrometry confirms the substitution of 1-6 Fe atoms with the single Fe-substituted cluster being the dominant species. The Fe-substituted clusters oxidize in solution to generate dicationic species. In contrast, only a single Ni-substituted cluster is observed, which remains stable as a singly charged species. Collision-induced dissociation experiments indicate the reduced stability of the [Co5 FeS8 L6 ]+ toward ligand loss in comparison with the unsubstituted and Ni-substituted counterparts. Density functional theory calculations provide insights into the effect of metal atom substitution on the stability and electronic structures of the clusters. The results indicate that Fe and Ni have a different impact on the electronic structure, optical, and magnetic properties, as well as ligand-core interaction of [Co6 S8 L6 ]. This study extends the atom-by-atom substitution strategy to the metal chalcogenide superatoms providing a direct path toward designing novel atomically precise core-tailored superatoms.
Keywords: atom-by-atom substitution; cobalt sulfide cluster; mass spectrometry; superatom.
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