title: Heterometallic triiron-oxo/hydroxo clusters: effect of redox-inactive metals.
abstract: A series of tetranuclear oxo/hydroxo clusters comprised of three Fe centers and a redox-inactive metal (M) of various charge is reported. Crystallographic studies show an unprecedented Fe3M(μ4-O)(μ2-OH) core that remains intact upon changing M or the oxidation state of iron. Electrochemical studies reveal that the reduction potentials (E1/2) span a window of 500 mV and depend upon the Lewis acidity of M. Using the pKa of the M-aqua complex as a measure of Lewis acidity, these compounds display a linear dependence between E1/2 and acidity, with a slope of ∼70 mV per pKa unit. The current study of [Fe3MO(OH)] and previous ones of [Mn3MOn] (n = 2,4) moieties support the generality of the above relationship between the reduction potentials of heterometallic oxido clusters and the Lewis acidity of incorporated cations, as applied to clusters of different redox-active metals.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: David E
authors.initials: DE
authors.lastname: Herbert
authors.forename: Davide
authors.initials: D
authors.lastname: Lionetti
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rittle
authors.forename: Theodor
authors.initials: T
authors.lastname: Agapie
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D004563:Electrochemistry; D007501:Iron / Q000737:chemistry*; D008673:Metals, Alkaline Earth / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D008673:Metals, Alkaline Earth; D019216:Metals, Heavy; D007501:Iron; D010100:Oxygen