Easy preparation of the tris(2-fluoro-6-pyridylmethyl)amine ligand and instantaneous reaction of the corresponding dichloroferrous complex with molecular dioxygen: New access to dinuclear species

The tris(2-fluoro-6-pyridylmethyl)amine ligand, F(3)TPA, can easily be prepared by reaction of 2-fluoro-6-bromomethylpyridine with NH4Cl in the presence of NaOH. Complexation to FeCl2 affords the high-spin F(3)TPAFe((II))-Cl-2 complex, the X-ray structure of which is reported. The three fluorine substituents provide enough steric hindrance to force the tripod to coordinate in the tridentate mode, affording a trigonal bipyramidal iron center. This complex is thermally stable, and it reacts instantaneously with molecular dioxygen to afford the unsymmetrical mu-oxo dimer F(3)TPAFe((III))ClOFe((III))Cl(3) as the major product, together with small amounts of the mixed salt [F(3)TPAFe((II))Cl](2), [(Fe2OCl6)-O-(III)]. These two complexes have been isolated and characterized by X-ray diffraction analysis. A mechanism by which they are obtained is suggested and seems to parallel the well-known process of autoxidation of ferrous porphyrins.