Exploration of the Solid- and Solution-State Structures and Electrochemical Properties of Ce^IV(atrane) Complexes

Chemical oxidation of cerium complexes can be unpredictable because of labile metal-ligand bonds leading to ligand redistribution. The use of tripodal frameworks such as silyl-substituted tren ligands (NN'₃ = [N(CH₂CH₂N(SiMe₂^tBu))₃]^3-) and a tris(hydroxylaminato) ligand, [((2- ^tBuNO)C₆H₄CH₂)₃N]^3- (TriNOx^3-), has been shown to mitigate ligand redistribution effects to allow access to tetravalent cerium complexes with different apical ligands. In the current work, the coordination chemistry of Ce^IV with the related tripodal atrane^3- (H₃atrane = [N(CH₂C(CH₃)₂OH)₃]) ligand framework was examined. A series of Ce^IV(atrane) complexes with supporting chloride, silylamide, and aryloxide ligands were synthesized and characterized by X-ray crystallography. The solution-state behaviors of these complexes were studied using ¹H and diffusion-ordered (DOSY) NMR spectroscopies. The electrochemical stabilization of the Ce^IV cation within the atrane^3- framework was examined. Our results showed that a combination of suitable apical ligands and the atrane framework provided excellent stabilization for the Ce^IV cation.