A Redox-Active Hydrogen Bond Acceptor Enables Ligand Exchange in a Zinc Complex

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Redox-Active Ligands

Background:

• Hydrogen bonding plays a crucial role in molecular recognition and stabilizing structures.
• Controlling ligand binding at metal centers is fundamental in catalysis and materials science.
• Redox-active molecules offer tunable electronic and steric properties.

Purpose of the Study:

• To investigate the influence of hydrogen bond strength on ligand binding in a zinc complex.
• To explore the use of a redox-active ferrocenecarboxylate ligand for controlling ligand substitution.
• To determine if redox modulation of hydrogen bonding can facilitate metal-ligand exchange.

Main Methods:

• Design and synthesis of a zinc complex with a ferrocenecarboxylate ligand.
• Electrochemical oxidation of the ferrocenecarboxylate moiety.
• Ligand substitution studies using trifluoromethanesulfonate.
• Control experiments to assess the necessity of oxidation and hydrogen bonding.

Main Results:

• Oxidation of the ferrocenecarboxylate enabled facile ligand substitution.
• Ligand substitution did not occur without prior oxidation of the redox-active component.
• Hydrogen bonding interactions were confirmed as essential for the observed substitution.
• Redox-tuning of the hydrogen bond acceptor was achieved at a mild redox potential.

Conclusions:

• The strength of hydrogen bonds, modulated by redox potential, can effectively control ligand binding at a metal center.
• Redox-switchable hydrogen bonding provides a novel strategy for facile and controlled ligand substitution in metal complexes.
• This approach offers a mild and tunable method for manipulating coordination environments.