Controlled Redox Chemistry at Cerium within a Tripodal Nitroxide Ligand Framework

Ligand reorganization has been shown to have a profound effect on the outcome of cerium redox chemistry. Through the use of a tethered, tripodal, trianionic nitroxide ligand, [((2-tBuNOH) C6H4CH2) 3N](3-) (TriNO(x)(3-)), controlled redox chemistry at cerium was accomplished, and typically reactive complexes of tetravalent cerium were isolated. These included rare cationic complexes [Ce(TriNO(x))thf] [BAr4F], in which Ar-F = 3,5-(CF3)(2)-C6H3, and [Ce(TriNO(x))py]OTf]. A rare complete Ce-halide series, Ce(TriNO(x))X, in which X= F-, Cl-, Br-, I-, was also synthesized. The solution chemistry of these complexes was explored through detailed solution-phase electrochemistry and H-1 NMR experiments and showed a unique shift in the ratio of species with inner- and outer-sphere anions with size of the anionic X- group. DFT calculations on the series of calculations corroborated the experimental findings.