Nanoclusters consist of a core of atoms that are usually protected with surface ligands, intermediate in size between single atoms and nanoparticles. Their high surface to volume ratio, unique electronic structure, and tunability makes them a great candidate as a model system for fundamental studies and application in catalysis, energy storage, and molecular electronics. In this study, we designed nanoclusters using atom-by-atom substitution to replace one of the Fe atoms in the core of [Fe₆S₈L₆]^+/2+cluster with other transition metals. Because the core determines the overall properties of the nanocluster, this is an effective method for tuning the electronic and magnetic properties of the cluster. We synthesized nanoclusters based on the iron sulfide and nickel sulfide cluster protected with triethylphosphine ligand (PEt₃) and analyzed them using high resolution mass spectrometry. Mass spectrometric analysis showed that when FeCl₂ is used as a metal precursor in the synthesis singly and doubly charged cationic species are formed [Fe₆S₈L₆]^+/2+(L=PEt₃). Meanwhile, using NiCl₂ as a metal precursor generates singly charged [Ni₃S₃HL₅]⁺ cluster with the same synthetic procedure. We examined the substitution of Ni atom to the core of [Fe₆S₈L₆]^+/2+clusters by using 1:1 molar ratio of NiCl₂ and FeCl₂. Mass spectrometric analysis revealed signals corresponding to [Fe₅NiS₈L₆]⁺, [Fe₄Ni₂S₈L₆]⁺, [Fe₅NiS₈L₅]²⁺, and [Fe₄Ni₂S₈L₅]²⁺species indicating that [Fe₆S₈L₆]^+/2+cluster undergoes atom-by-atom substitution. The core of the [Ni₃S₃HL₅]⁺ cluster does not undergo substitution with Fe atoms. This work increases the range of atomically precise alloy nanoclusters that have potential applications in molecular electronics, spintronics, quantum computing, and energy storage.

Dylan Forbes

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