Mono-, di-, and tri-nuclear complexes of iron(II) with N,N,N',N'-tetramethylethylenediamine

Iron(II) chloride reacted with N,N,N',N'-tetramethylethylenediamine (tmen) in tetrahydrofuran (thf) to give the mononuclear complex trans-[FeCl2(tmen)(2)] 1 and the dinuclear complex [{FeCl(tmen)(2)}(2)(mu-Cl)(2)] 2. Both adducts were characterised by microanalyses, magnetic measurements, Mossbauer spectroscopy, and crystal structure analysis. In solution in thf the two species are in an equilibrium affected by temperature and by concentration of tmen. Reaction of either 1 or 2 with Na[BPh4] produced the trinuclear species [Fe-3(mu-Cl)(3)(mu(3)-Cl)(2)(tmen)(3)][BPh4] 3. This compound is paramagnetic both in the solid state and in solution. These iron complexes are very similar in structure to the corresponding vanadium complexes.