Synthesis and characterization of monomeric (aryloxo)iron complexes: [Fe(II)L(OAr)] and [Fe(III)L(OAr)(2)] {L=BH(3,5-Pr(2)(i)pz)(3)(-)}

A series of (aryloxo)iron(II) complexes [Fe{BH(3,5-Pr(2)(1)pz(3)}(OAr))] (Ar = C6H5 (4); C6H4-p-Cl (5); C6H4-p-F (6); C6H4-p-Me (7); C6H3-2,6Cl(2) (8); C6F5 (9)) were synthesized by the anion ligand replacement of [Fe(Cl){BH(35-Pr(2)(1)pz)(3)}] (1) with NaOAr. Crystallography was performed for 1 and 9. All these tetrahedral (aryloxo)iron(II) complexes react with dioxygen readily, to afford the bis(aryloxo)iron(III) complexes [Fe{BH(3,5-Pr(2)(1)pz)(3)}(OAr)(2)] (Ar = C6H5 (10); C6H4-p-Cl (11); C6H4-p-F (12); C6H4-p-Me (13); C6H3-2,6-Cl-2 (14); C6F5 (16)) as sole isolable products (the maximum yield based on the iron(II) complex was ca. 50%). The MeCN adduct of 13 was structurally characterized by X-ray crystallography.