Efficiently transforming CO₂ into value-added chemicals like CO, MeOH, or hydrocarbons requires innovative solutions to lower the thermodynamic and kinetic hurdles that impede CO₂ reduction. One potential approach for CO₂ activation involves designing organometallic complexes to support metal-ligand cooperative (MLC) binding, where CO₂ simultaneously bonds with both a metal and ligand. This contrasts conventional methods where only the metal participates in binding and activation.
Our groups previously reported that Ru complexes containing a redox-active triaryl N₂S₂ ligand derived from o-phenylenediamine (L1) can undergo MLC binding with BH₃ in a similar way to that observed for CO₂ in other complexes. Cyclic voltammetry (CV) and density functional theory (DFT) studies show that MLC attenuates ligand-centered redox activity in L1 and complexes with related tetradentate ligands, though electron transfer can still occur as long as one redox-active site remains unengaged in MLC. These findings suggest that incorporating multiple reactive sites may preserve ligand-centered redox activity while maintaining MLC reactivity.
This previous research inspired a series of experiments to determine if Ru complexes contain L1 and related tetradentate ligands will bind CO2 via similar MLC interactions observed with BH₃. Though preliminary results suggest that MLC binding with CO₂ is less likely, CV studies suggest that several of the Ru complexes are competent for CO₂ electrocatalysis. In this talk, I will present X-ray diffraction, UV-vis spectroscopy, and cyclic voltammetry studies used to assess MLC binding of the Ru complexes with BH₃. Cyclic voltammograms collected in the presence and absence of CO₂ will also be described alongside data used to identify and quantify CO₂-derived reduction products formed under reducing potentials.

Fateme Parsapour

Appearances