A mixed-valence metallogrid [CoCo] with an unusual electronic structure and single-ion-magnet characterization.

The reaction of the multisite coordination ligand (HL) with Co(Ac)·4HO in the absence of any base affords a homometallic tetranuclear mixed-valence complex, [Co(L)(CHCO)(CHOH)]·EtO (1). This mixed-valence metallogrid [Co(L)(CHCO) (CHOH)]·EtO (1) has been theoretically and experimentally analyzed to assign the valence and spin state in the form of trans-[Co-Co-Co-Co]. HF-EPR reveals the presence of axial anisotropy (D = -34.4 cm) with a significant transverse component (E = 9.5 cm) in the local high spin cobalt centers. Slow magnetic relaxation effects were observed in the presence of a dc field, demonstrating field-induced single ion magnetic behavior, which is associated with the unusual electronic structure of Co(ii) within the metallogrid.