Trinuclear Oxo‐Centered Iron and Iron/Nickel Clusters – Ligand‐Controlled Homo/Hetero Valency

Cleavage of the all‐iron(III) μ2‐O2–‐linked dimer [FeIII3O(L)2‐(OAc)4]2O (3) with lithium chloride yields [FeIII3O(L)2(OAc)4]Cl (4) and with sodium benzoate, in combination with complete acetate‐to‐benzoate coligand exchange, gives [FeIII3O(L)2‐(OBz)4]OBz (5). Reduction of the all‐FeIII complex 5 [Fe/L/OBz = 3:2:(4+1)] with sodium iodide affords the homonuclear mixed‐valent cluster [FeIIFeIII2O(L)3(OBz)3] (6) (Fe/L/OBz = 1:1:1) and requires fundamental coligand‐to‐ligand exchange. Likewise, when the all‐FeIII dimer [FeIII3O(L)2(OAc)4]2O (3) (Fe/L/OAc = 3:2:4) is cleaved with nickel acetate, the mixed‐valent heteronuclear complex [NiIIFeIII2O(L)3(OAc)3] (7) (M/L/OAc = 1:1:1) is formed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)