Inorganic Chemistry, Vol.57, No.15, 8769-8777, 2018
Aliphatic C-H Bond Halogenation by Iron(II)-alpha-Keto Acid Complexes and O-2 : Functional Mimicking of Nonheme Iron Halogenases
alpha-Ketoglutarate-dependent nonheme halogenases catalyze the halogenation of aliphatic C-H bonds in the biosynthesis pathway of many natural products. An iron(IV)-oxo-halo species has been established as the active oxidant in the halogenation reactions. With an objective to emulate the function of the nonheme halogenases, two iron(II)-alpha-keto acid complexes, [(phdpa)Fe(BF)Cl] (1) and [(1,4-tpbd)Fe-2(BF)(2)Cl-2] (2) (where phdpa = N,N-bis(2-pyridylmethyl)aniline, 1,4-tpbd = N,N,N',N'-tetrakis(2-pyridylmethyl)benzene-1,4-diamine, and BF = benzoylformate), have been prepared. The iron complexes are capable of carrying out the oxidative halogenation of aliphatic C-H bonds using O-2 as the terminal oxidant. Although the complexes are not selective toward C-H bond halogenation, they are the only examples of nonheme iron(II)-alpha-keto acid complexes mimicking the activity of nonheme halogenases. The dinuclear complex (2) exhibits enhanced reactivity toward C-H bond halogenation/hydroxylation.