A Heptanuclear Iron(III) Oxo-Carboxylate Cluster†‡

A new heptanuclear iron(III) oxide pivalate cluster [Fe7O4(OH)2(O2CCMe3)11(bpm)2(H2O)] (1) (bpm = 2,2′-bipyrimidine) has been prepared and characterized. 1 features an asymmetric {Fe7O6} framework based on two corner-sharing {Fe4(μ3-O)2} groups, themselves comprising {Fe3(μ3-O)} motifs that are formally retained from the {Fe6O4} precursor used in thesynthesis of 1. Compared to existing FeIII oxide carboxylate clusters, the {Fe7O6} fragment in 1 exhibits an unusually high Fe:O ratio, with all seven oxygen sites efficiently mediating magnetic exchange. Correspondingly, 1 shows strong intramolecular antiferromagnetic coupling.