The structural, electronic, and magnetic properties of neutral and charged FenS(2)(0/+/-) (n = 1-6) clusters have been calculated in the framework of the density functional theory in the generalized gradient approximation for the exchange and correlation. The calculated adiabatic electron affinity and the vertical detachment energy are found to be in good agreement with the available experimental data. The impact of disulfide-doping of small iron clusters on the atomic structure, stability, magnetic moment, and reactivity is determined through the analysis of the binding energy per atom, electronic charge transfer, spin-polarized electronic densities of states, and global reactivity electronegativity and chemical hardness. Our results provide an exhaustive characterization of these small under vacuum, which is the first step to completely understand their role as components of proteins. indicators like the iron-sulfide particles under vacuum, which is the first step to completely understand their role as components of proteins.