Unusual oxidative stability of a multidentate primary amine ligand: facile synthesis of the oxo-bridged diiron(III) complex

The tetrapodal pentaamine 2,6-C5H3N[CMe(CH2NH2)2]2 (pyN4, 1), which possesses four equivalent primary amino groups, has been used to prepare the diiron(III) oxo complex [(1)2Fe2(μ2-O)](ClO4)4(2), by aerobic oxidation of the mononuclear iron(II) aqua complex in methanol. This synthesis is unusual because iron(II) complexes of primary amines are normally unstable with respect to metal-induced ligand oxidation. X-ray as well as Mössbauer data indicate a high-spin electronic configuration for the metal centres in the dinuclear complex.