Variable-temperature 1H and 13C NMR spectra of H2FeRu3(CO)13, H2FeRu2Os(CO)13, and H2FeRuOs2(CO)13 have been measured and interpreted in view of three distinct fluxional processes. In the lowest temperature process the bridging and terminal carbonyls bound to Fe undergo localized exchange. The second process involves migration of the carbonyls around the face of the tetrahedral cluster that contains the bridging carbonyls. The highest temperature process involves a subtle reorganization of the metal framework. This latter process accounts for interconversion of the two enantiomers of the Q isomer of H2FeRu2Os(CO)13 and H2FeRuOs2(CO)13 and allows for the Cs ⇄ C1, isomerization. Line-shape analysis of the 1H NMR spectra and comparison of the 13C NMR spectra show that the activation barrier for each process increases as the Os content of the cluster increases.