Dramatically accelerated selective oxygen-atom transfer by a nonheme iron(IV)-oxo complex: Tuning of the first and second coordination spheres

Abstract

The new ligand N3PyamideSR and its FeII complex [FeII(N3PyamideSR)](BF4)2 (1) are described. Reaction of 1 with PhIO at -40 C gives metastable [Fe IV(O)(N3PyamideSR)]2+ (2), containing a sulfide ligand and a single amide H-bond donor in proximity to the terminal oxo group. Direct evidence for H-bonding is seen in a structural analogue, [Fe II(Cl)(N3PyamideSR)](BF4)2 (3). Complex 2 exhibits rapid O-atom transfer (OAT) toward external sulfide substrates, but no intramolecular OAT. However, direct S-oxygenation does occur in the reaction of 1 with mCPBA, yielding sulfoxide-ligated [Fe II(N3PyamideS(O)R)](BF4)2 (4). Catalytic OAT with 1 was also observed. © 2014 American Chemical Society.