Tuning Reactivity and Electronic Properties through Ligand Reorganization within a Cerium Heterobimetallic Framework

Cerium
compounds have played vital roles in organic, inorganic,
and materials chemistry due to their reversible redox chemistry between
trivalent and tetravalent oxidation states. However, attempts to rationally
access molecular cerium complexes in both oxidation states have been
frustrated by unpredictable reactivity in cerium­(III) oxidation chemistry.
Such oxidation reactions are limited by steric saturation at the metal
ion, which can result in high energy activation barriers for electron
transfer. An alternative approach has been realized using a rare earth/alkali
metal/1,1′–BINOLate (REMB) heterobimetallic framework,
which uses redox-inactive metals within the secondary coordination
sphere to control ligand reorganization. The rational syntheses of
functionalized cerium­(IV) products and a mechanistic examination of
the role of ligand reorganization in cerium­(III) oxidation are presented.