The 48e cluster OS,(CO)~,(~-P~-DAB (~~))(Lb) lb with a chelating &donating i-Pr-DAB ligand (abbreviated as i-Pr-DAB (4e)) is converted in refluxing n-hexane into the 50e cluster OS~(CO)~,,(~-P~-DAB (G~))(2b) with a bridging 6e-donating i-Pr-DAB ligand (abbreviated as i-Pr-DAB (6e)). By further heating 2b is decarbonylated to give Os3 (C0),(i-Pr-DAB (8e))(3b) with an Be-donating i-Pr-DAB ligand (abbreviated as i-Pr-DAB (8e)). Under ...