Our goal is to address challenges in energy and the environment by employing and advancing our expertise in fundamental inorganic and physical inorganic chemistry. Some examples of our current interests and projects are described below.

C-H Bond Formation with CO2 with Multi-Metallic Clutsers

Electrochemical methods for the production of fuels can convert electricity (electrons) via a chemical redox reaction into a fuel. In this way, a fuel provides an energy dense, transportable means to store renewable energy. With production of renewable electricity in over supply, its conversion to a fuel makes economic sense. We are investigating multimetallic ensembles of earth-abundant iron and cobalt atoms and atomic-level understanding of the reactions of protons with metal clusters under electrochemical conditions has been probed to control competing reactions such as hydrogen evolution and CO2 reduction to formic acid. Metal-hydride catalyst intermediates can react with H+ or with CO2 and we wish to understand how to selectively direct competing reactions and favor CO2 reduction. The effect of cluster size (2 - 13 metal atoms) on catalysis, the effects of tuning the secondary coordination sphere, and thermochemical vs. kinetic control of reaction pathway, are ongoing areas of investigation. This work involves organometallic synthesis and characterization, and advanced use and development of cyclic voltammetric methods to probe reactions, mechanism and kinetics. Students can specialize in one or both of these areas.

Ligand-Based Proton and Electron Transfer with Aluminum(III) Complexes

In principle, cheap and abundant elements such as aluminum (8% in the earth's crust) are appealing for large scale applications such as catalysis. By addition of redox active ligands to aluminum, the Berben lab can now access aluminum complexes in five oxidation states. Using these complexes we can perform classic transition metal reactions such as one- or two-electron oxidation chemistry, O- or N-atom transfer, and C-H activation. Generation of organic hydrides via ligand protonation and reduction, C-F amination chemistry, and explorations of square planar Group 13 electonic structures are areas of ongoing interest. This work includes inorganic, air-free synthesis, structural characterization and electrohemical methods to probe catalytic and mechanistic aspects.

Organic Electron Transfer and Mixed-Valency

Classic mixed-valent compounds involve two metals, in different oxidation states, and linked by a conjugated organic bridge. Our work explores highly delocalized systems where two redox-active ligands are linked by Group 13 elements. In addition to the synthesis and fundamental studies of electron delocalization we explore these compounds in applications such as redox-flow batteries, and organic electronic materials. This work includes inorganic and organometallic synthesis and characterization, and spectroscopic and electrohemical methods to probe mixed-valency and electron transfer.

Synthesis of Low-Coordinate Complexes using Bulky Acetylide Ligands

Acetylide is a strongly donating ligand and it is well-known that strongly donating and tunable ligands such as phosphines and N-heterocyclic carbenes feature prominently in transition metal synthesis and catalysis. However, unlike phosphine and N-heterocyclic carbene ligands, facile routes to substituted acetylide ligands are not readily available. We are exploring whether the more donating and anionic acetylide ligand can also serve as a tunable and highly donating ancillary ligand.