Structural variation in cerium aryloxide complexes templated by hemilabile K+–amine interactions

Abstract

A series of complexes with the formula K[Ce(OAr)(bdmmp)₃] (Ar = –C₆H₅ (–Ph), –C₁₀H₇ (–Naph), –2,4-tBu-C₆H₃ (–dtbp) and –2,6-Ph-C₆H₃ (–dpp)) and K[Ce(OAr)₂(bdmmp)₂] (Ar = –2,6-iPr-C₆H₃ (–dipp)) (bdmmp = (bis(dimethylamino)methyl-4-phenolate)) are presented. The complexes were obtained through metathesis and protonolysis reactions from K[Ce(OTf)(bdmmp)₃] or K[Ce(OtBu)(bdmmp)₃] respectively. X-ray diffraction studies provide insight into the effect of the steric profile of the aryloxide ligand on perturbing the templating effect of the K⁺ ion with the pendent tertiary amine groups of the bdmmp⁻ ligands. Characterization of the various aryloxide derivatives through cyclic voltammetry and variable temperature ¹H NMR studies demonstrate the impact of the substituents on the solution dynamics and redox properties. Additionally, an unusual example of a terminal cerium(III) hydroxide complex was isolated and characterized in solid state and in solution using the bdmmp framework.