Tunable intramolecular multicenter H-bonding interactions in first-row metal complexes bearing bidentate redox-active ligands.

In this research article, we report the synthesis and structural characterization of a family of first-row metal complexes bearing redox-active ligands with tunable H-bonding donors. We observed that these coordination complexes can adopt three different geometries and that they are stabilized by intramolecular multicenter H-bonding interactions, which are systematically modified by changing the metal ion (Co, Ni, Cu, Zn), the ligand scaffold (variations in the diamine and ureanyl substituents used) and the solvent of crystallization.

Catalytic Aerobic Oxidation of Alcohols by Copper Complexes Bearing Redox-Active Ligands with Tunable H-Bonding Groups.

In this research article, we describe the structure, spectroscopy, and reactivity of a family of copper complexes bearing bidentate redox-active ligands that contain H-bonding donor groups. Single-crystal X-ray crystallography shows that these tetracoordinate complexes are stabilized by intramolecular H-bonding interactions between the two ligand scaffolds. Interestingly, the Cu complexes undergo multiple reversible oxidation-reduction processes associated with the metal ion (CuI, CuII, CuIII) and/or the o-phenyldiamido ligand (L2-, L•-, L). Moreover, some of the CuII complexes catalyze the aerobic oxidation of alcohols to aldehydes (or ketones) at room temperature. Our extensive mechanistic analysis suggests that the dehydrogenation of alcohols occurs via an unusual reaction pathway for galactose oxidase model systems, in which O2 reduction occurs concurrently with substrate oxidation.