Biomimetic Oxidation Studies. 8. Structure of a New MMO Active Site Model, [Fe2O(H2O)2(tris((1-methylimidazol-2-yl)methyl)amine)2]4+,and Role of the Aqua Ligand in Alkane Functionalization Reactions

In this communication, the authors report on an X-ray crystallographic study of a new methane monooxygenase (MMO) active site analogue, [Fe{sub 2}O(H{sub 2}O){sub 2}(tmima){sub 2}]-(ClO{sub 4}){sub 4}, 2, and on important mechanistic aspects of the C-H bond functionalization reaction of several hydrocarbons with 2 as the catalyst using anhydrous TBHP in the presence of oxygen gas (O{sub 2}) and acetonitrile (CH{sub 3}CN) as the solvent. The authors will demonstrate that, by removing the {mu}-OAc group and replacing it with terminal H{sub 2}O ligands, complex 2 enhances the number of turnovers/h for the alkane functionalization reaction, while UV-vis and {sup 1}H NMR spectroscopic data suggest that 2 retains its integrity upon reaction with TBHP. In addition, the authors have further verified the previously found free radical mechanism for alkane functionalization {sup 1e,g} with 2 by the use of a radical clock substrate, trans-2-phenylmethylcyclopropane, to show only ring-opened products that must emanate from a cyclopropylcarbinyl radical rearrangement.