Complex coalt-carbonyl ligand-based clusters of clusters are used as molecular precursors for self-supported model catalysts. These precursors present two metal layers. The outer layer is associated with the complex Co-carbonyl ligands, and the core layer, which is either cobalt or zinc. These two precursors are identified as CoCo and ZnCo, respectively. In situ DRIFTS, TGA, TPD-MS, XPS, and catalytic measurements show two distinct forms of the catalysts. Partial thermolysis at low temperature (LT) under hydrogen results in almost completely decarbonylated catalysts, which appear to posses a mainly unchanged carboxylate metal core. Complete pyrolysis at higher temperatures (HT) in hydrogen leads to a mixed metal environment. The activities of the catalysts are studied in the hydrogenation of 1,3-butadiene. The LT series show similar catalytic behavior during the hydrogenation of 1,3-butadiene. However, significantly different catalytic behavior is observed between the HT catalysts. The effect of the core metal on the d-electron density appears to be the factor leading to very different catalytic behavior patterns.