Nature uses high oxidation state metal centers to perform a variety of important transformations, including C-H bond activation and O-O bond formation.  Additionally, transition metal ions in the 4+ oxidation state are often cited as intermediates in numerous catalytic transformations, such as water oxidation.  However, isolation of these intermediates has proven difficult due to their reactive, and often highly oxidizing, nature. The Hayton group has been exploring the ability of the ketimide ligand, [N=CR₂]^-, to stabilize transition metal complexes in the 4+ oxidation state, and have successfully isolated a novel series of M(IV) tetra(ketimide) complexes, M(N=C^tBu₂)₄ (M = Mn, Fe, Co).  We employ a number of characterization methods to explore the properties of these materials, including NMR, IR, EPR, and UV/vis-NIR spectroscopies, SQUID magnetometry, and cyclic voltammetry.  We are currently exploring the reactivity of these complexes in an effort to better understand the properties of high oxidation state metal ions.