[en] The authors have performed a linear combination of Gaussian-type orbitals, LCGTO, local density functional, LDF, calculations on a series of low- and high-nuclearity carbonylated Ni clusters and on their naked counterparts. The authors have found that while the bare Ni clusters do exhibit several features in common with the bulk metal, the low-nuclearity carbonylated clusters do not show any metallic behavior. Signs of a developing metallic character are found for high-nuclearity Ni cluster carbonyls where it is possible to distinguish between open-quotes surfaceclose quotes atoms, which are directly interacting with the ligand sphere, and open-quotes bulkclose quotes atoms, which are only interacting with other metal atoms. Through the analysis of the magnetic properties of these systems it is possible to formulate a general model which rationalizes both the metallic behavior of the free Ni clusters and the nonmetallic behavior in certain carbonylated Ni clusters. This model is based on the perturbations induced by the ligands on the electronic structure of the metal atoms in the cluster