Exploration of the Solid- and Solution-State Structures and Electrochemical Properties of CeIV(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(SiMe2tBu))3]3-) and a tris(hydroxylaminato) ligand, [((2- tBuNO)C6H4CH2)3N]3- (TriNOx3-), 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 CeIV with the related tripodal atrane3- (H3atrane = [N(CH2C(CH3)2OH)3]) ligand framework was examined. A series of CeIV(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 CeIV cation within the atrane3- framework was examined. Our results showed that a combination of suitable apical ligands and the atrane framework provided excellent stabilization for the CeIV cation.