A novel bis-β-diketonate ligand stabilizes a [Co(II)8] cage that encapsulates a (μ3-O)⋯H⋯(μ3-O) moiety

The novel ligand 1,3-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-2-pyridine, H4L, is used here for the first time. In a reaction with Co(II) it produces the complex salt [Co8O(OH)(H2L) 6]NO3 (1), containing an octametallic cluster cation. The topology of this cluster, which encapsulates a rare (μ3-O) ⋯H⋯(μ3-O) at its interior, exhibits a remarkable similarity to the cofactor of nitrogenase FeMoco. It features intramolecular antiferromagnetic interactions, which can be simulated using a spin-only model, yielding an S = 0 spin ground state, lying very close to numerous excited states.GA thanks the Generalitat de Catalunya for the prize ICREA Academia 2008 and the ERC for a Starting Grant (258060 FuncMolQIP). The authors thank the Spanish MCI through CTQ2009-06959 (LAB) and MAT2011-24284 (OR), and the ERC for a Predoctoral Fellowship under Grant 258060 FuncMolQIP.Peer reviewe