This dissertation discusses the synthesis, characterization, and reactivity of site-differentiated tetranuclear clusters containing Fe and Mn with NO and H2O-derived ligands. The motivation of this work was to conduct a detailed examination of structure-property relationships in well-defined molecular systems focused on unique features of multinuclear systems, such as bridging ligands, neighboring metal identity, and cluster oxidation state. Reactivity towards NO and H2O-derived ligands was

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... eted due to their relevance to biological multinuclear transition metal active sites that promote multi-electron small molecule transformations. Chapter 2 discusses the synthesis of Fe-nitrosyl clusters bearing an interstitial μ4-F atom. These clusters were prepared to compare their reactivity to previously synthesized [Fe33OFeNO] clusters with an analogous structure. A redox series of the [Fe3FFe] and [Fe3FFeNO] clusters were accessed, with the nitrosyl clusters displaying five cluster oxidation states, from FeII3{FeNO}8 to FeIII3{FeNO}7. Overall, the weaker bonding of the F- ligand resulted in attenuation of the activation and reactivity of the {FeNO}7, relative to the corresponding μ4-O clusters. Furthermore, the ability of distal Fe oxidation state changes to influence the activation of NO was decreased, demonstrating lower cooperativity between metals in clusters linked by a weaker μ4-atom This represents a rare case where the effects of bridging atom ligands could be compared in isostructural multinuclear complexes and decoupled from changes in metal ion coordination number, oxidation states, or geometry. Chapter 3 describes the synthesis of site-differentiated heterometallic clusters of [Fe3OMn], displaying facile ligand substitution at the five-coordinate Mn. This system was able to coordinate H2O and thermodynamic parameters of the proton and electron transfer processes from the MnII–OH2 to form a MnIII–OH moiety were studied. The oxidation state distribution of the neighboring Fe centers had a significant influ [...]