Catalytic studies of an Fe(III) macrocyclic tetradentate triamide complex with hydrogen peroxide

INOR 659

Erich S. Uffelman, uffelmane@wlu.edu, Christopher M. Diebold, Emily A. Binns, Carly S. Levin, Scot B. Pittman, Elizabeth G. Webb, and Kehvon M. Clark. Department of Chemistry, Washington and Lee University, Lexington, VA 24450
A macrocyclic tetradentate triamide ligand system has been successfully metalated with anhydrous ferric chloride and reacted with cyanide to produce an axial bis-cyano iron(III) complex that has been characterized by paramagnetic NMR spectroscopy, electrospray MS, IR, and cyclic voltammetry. The electrochemistry reveals an unusually low Fe(IV)/Fe(III) couple, and the iron(IV) complex, which is stable for hours at room temperature, has been characterized by paramagnetic NMR spectroscopy. The X-ray structures of the bis-imidazole iron(III) complex and of the free ligand are compared to the X-ray structures of a tetraamido macrocyclic ligand (TAML) and its iron complexes that have generated over 100 patents in iron chemistry that catalyzes environmentally friendly Green oxidation with hydrogen peroxide. The hydrogen peroxide-based catalysis of the new complex is presented, along with comparison to its derivatives.