Ferromagnetic Coupling in the Bis(μ‐end‐on‐azido)iron( III ) Dinuclear Complex Anion of [FeII(bpym)3]2[Fe(N3)10]·2H2O

An energetically low-lying spin state with S = 5 is observed in the title compound, in which low-spin iron(II) [Fe(bpym)3]2+ and high-spin iron(III) [Fe2(N3)10]4− ions coexist. The magnitude of the ferromagnetic coupling in the dimer (J = + 4.8 cm−1) is twice that reported for a high-spin MnII complex with the same bridging ligands. The structure of the anion is shown on the right.