Multinuclear first-row transition metal clusters containing bridging one-atom ligands to three or more metal ions are found in complex biological active sites including the Oxygen Evolving Complex in Photosystem II (μ3- and μ4-oxo ligands), and the iron-molybdenum cofactor in nitrogenase (μ6-carbide). Synthetic tetranuclear clusters have been studied with the goal of understanding how an interstitial atom can affect the chemistry of the cluster. These model complexes are composed of a trimetallic core which is connected to an apical metal center by three pyrazolate ligands, and a μ4-atom (μ4-F and μ4-O). The apical metal center possesses a trigonal pyramidal geometry with an open coordination site. The intermolecular chemistry of these bio-inspired clusters has been investigated to understand the effect of the neighboring metals and bridging atom. When the pyrazolate ligands display phenyl substituents, intramolecular C–H and C–F bond functionalization occurs upon reaction with oxygen atom transfer (OAT) reagents. More sterically open tetrairon clusters with μ4-F and μ4-O interstitial ligands and no phenyl substituents have been synthesized. Reactions with OAT reagents suggest the formation of terminal iron-oxo intermediates. The reactivity and properties of these clusters as a function of the μ4-interstitial atom will be discussed.

Structure-function studies of tetranuclear iron clusters with a variable interstitial μ4-atom as models of biological active sites

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.