Synthesis, structure, magnetic and electrochemical properties of an oxydiacetate iron(II) complex

Compound [{Fe(oda)(H2O)2} · H2O]n (1) [oda=O(CH2COO)2 2−] has been obtained by reaction of FeCl2 · 4H2O with a 1:1 mixture of O(CH2COOH)2 and Na2CO3 in water. The structure is polymeric with concatenated {Fe(oda)(H2O)2} units extended in one direction. Each iron centre is six-coordinated by the tridentate planar oda ligand, two mutually trans water molecules and one oda oxygen atom from an adjacent {Fe(oda)(H2O)2} unit. Complex 1 is isomorphous with cobalt and zinc analogues. Magnetic susceptibility measurements down to 2 K showed high-spin non-correlated Fe(II) ions with a typical Curie–Weiss behaviour. Differential-pulse voltammetry establishes a value of 0.488 V versus NHE for the Fe(III)/Fe(II) redox potential of this iron complex in 0.25 mol dm−3 NaNO3.