Reactivity of a Bis(amidinato)iron(II) Complex [Fe(MesC(NPri)2)2] toward Some Oxidizing Reagents

Abstract

A diversified reactivity of the mononuclear bis(amidinato)iron(II) complex [Fe(MesC(NPr(i))2)2] (1) toward oxidizing reagents has been disclosed. The bis(amidinato)iron(II) complex was synthesized from the reaction of [Fe(Mes)2]2 with 4 equiv of diisopropyl carbodiimide in good yield. Treatment of 1 with 1 equiv of benzyl chloride gives the high-spin ferric complex [FeCl(MesC(NPr(i))2)2] (2), with 0.25 equiv of S8 affords the sulfur-insertion product [Fe(MesC(NPr(i))(NPr(i)S))2] (3), with 1 equiv of 3,5-dimethylphenyl azide or phenyl azide yields nitrene-insertion product [Fe(MesC(NPr(i))2)(Pr(i)NC(Mes)N(Pr(i))NAr)] (Ar = 3,5-dimethylphenyl, 4a; phenyl, 4b), and with 1 equiv of oxo-transfer reagent, trimethylamine oxide or 2,6-dichloropyridine oxide, generates the oxo-bridged diferric complex [(MesC(NPr(i))2)2FeOFe(MesC(NPr(i))2)2] (5). Complexes 1-3, 4a, and 5 have been characterized by (1)H NMR, UV-vis, IR, elemental analysis, and single-crystal X-ray diffraction studies. The formations of these unusual sulfur- and nitrene-insertion products 3, 4a, and 4b, can be explained by the sequential redox reaction between 1 and the oxidants, followed by migratory insertion steps.