A mixed-valence metallogrid [CoIII2CoII2] with an unusual electronic structure and single-ion-magnet characterization.

The reaction of the multisite coordination ligand (H2L) with Co(Ac)2·4H2O in the absence of any base affords a homometallic tetranuclear mixed-valence complex, [Co4(L)4(CH3CO2)2(CH3OH)2]·Et2O (1). This mixed-valence metallogrid [Co4(L)4(CH3CO2)2 (CH3OH)2]·Et2O (1) has been theoretically and experimentally analyzed to assign the valence and spin state in the form of trans-[CoIIIls–CoIIhs–CoIIIls–CoIIhs]. HF-EPR reveals the presence of axial anisotropy (D = −34.4 cm−1) with a significant transverse component (E = 9.5 cm−1) 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. [ABSTRACT FROM AUTHOR]