Selective dehydrogenation of amines with respect to coordination geometry: different oxidation products of tricyano[bis(2-pyridylmethyl)amine]ferrate(II) between mer- and fac-isomers

Both the fac- and mer-isomers of tricyano[bis(2-pyridylmethyl)amine = 2-DPA]ferrate(II) were isolated and their spectroscopic properties compared. The fac-isomer was converted to the corresponding iron(III) complex under acidic conditions. Oxidation of the ferrate(II) complexes with ammonium peroxodisulfate yielded the mer-isomer of the dehydrogenated ferrate(II) compound, but only the metal-oxidized iron(III) complex for the fac-isomer was produced under neutral or basic conditions. Electrochemical measurements confirmed this difference in the oxidation behavior, in which the nature of the coordination governs the ease of oxidative dehydrogenation.