Synthesis and structures of trinuclear and μ-hydroxo pentanuclear iron(II) carboxylates as models of reduced ferritin and white rust

Abstract

The synthesis of a trinuclear iron(II) complex and the syntheses and X-ray structural characterization of three pentanuclear complexes [Fe 5( μ 3-OH) 2(O 2CPh) 6(L) x (L′) x′ ](CF 3SO 3) 2 ( 8en: L = en, x = 4, x′ = 0; 8py: L = py, x = 8, x′ = 0; 8pyPrCN: L, L′; L = py, x = 6, L′ = PrCN, x′ = 2) are described. The structures are examples of the growth of clusters when the bulky multidentate terminal ligands of the water bridged complex, Fe 2(OH 2)(O 2CPh) 4(tmen) 2, or hydroxy bridged complex, [Fe 2(OH)(O 2CPh) 2(Me 3tacn) 2] +, are replaced by smaller ligands. These cores contain the first examples of μ 3OH in an iron(II) complex. The centrosymmetric core consists of a central octahedral iron ligated solely by oxygen surrounded by four additional iron octahedra which each share an edge with the central Fe. The planar arrangement of Fe 5 atoms resembles a fragment of a layered structure of white rust.