This presentation will describe our efforts to synthesize single-molecule magnets with well-isolated spin ground states by employing radical bridging ligands. In particular, a series of dinuclear metal complexes of the bridging ligand azophenine (NPhLH2), [(TPyA)2M2(NPhL2-]2+ (TPyA = tris(2-pyridylmethyl)amine; M = Mn, Fe, Co, Ni) has been synthesized. Chemical reduction of these species affords the corresponding radical-bridged complexes [(TPyA)2M2(NPhL�-]+, as confirmed by structural and spectroscopic analysis. Dc magnetic susceptibility measurements for the reduced complexes reveals the presence of strong antiferromagnetic exchange between MII centers and azophenine radical, with estimated coupling constants of J = -150 (Mn), -900 (Fe), -310 (Co), and J = -600 (Ni) cm-1. M�ssbauer spectroscopy and ac magnetic susceptibility reveal that the iron congener behaves as a single-molecule magnet with a spin relaxation barrier of Ueff = 50(1) cm-1. To our knowledge, this complex exhibits by far the strongest magnetic exchange yet observed in a single-molecule magnet.

Strong magnetic exchange coupling and slow magnetic relaxation in azophenine radical-bridged dinuclear complexes

248th National Meeting (2014)

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