Organometallic chemistry, inorganic chemistry, homogeneous catalysis, small molecule activation

The development of more efficient synthetic methods represents a major economic and environmental challenge for the chemical industry. With research interests that span the fields of inorganic and organic chemistry, we focus on the preparation and characterization of new transition metal complexes that are capable of activating organic molecules toward novel reactivity. By focusing on fundamental inorganic and organometallic chemistry, our efforts are directed toward the design of single-site catalysts that form the foundation of new synthetic methodologies. We apply our fundamental research toward chemical processes of relevance to the production and use of energy, the synthesis of large-scale chemicals as well as the fine chemical sector.

Petroleum distillates make up a considerable fraction of the synthetic building blocks available to the chemical industry and with a steep rise in demand, the efficient use of fossil resources is increasingly important. Carbon and hydrogen are the major elemental constituents of fossil-derived products. One area of focus for our group is the design of transition metal complexes that selectively break C–H bonds to enable reactivity towards useful products. For example, we are exploring the use of late transition metal systems for catalytic C–C bond formation reactions that proceed through transition metal-mediated C–H activation. Systems based on Ru, Pt, Rh and Ir developed in our labs catalyze the addition of aromatic (including arenes and heteroaromatic substrates) C–H bonds across the C=C bonds of olefins. The overall reactions result in arene alkylation or alkenylation. By understanding how the metal identity, metal oxidation state, and ancillary ligand impact the catalytic cycle, we can design improved catalysts.

Another area of interest is the development and study of catalysts for the selective partial oxidation of light alkanes. Natural gas is an abundant resource for chemicals, but current processes for the oxidation of light alkanes (methane, ethane, propane) to form alcohols are indirect and energy intense. As a result, distributed conversion at natural gas wellheads is not generally economical, which often results in natural gas flaring. We are studying new strategies for catalytic conversion of methane, ethane and propane to selectively generate methanol, ethanol and propanol. Our efforts are focused on both thermal and photo-driven processes. 

Recently, we also have initiated projects to elucidate mechanistic details for electrocatalytic water oxidation. This is a half-reaction for overall electrocatalytic splitting of water to form dihydrogen and dioxygen, which is one strategy for the scaled conversion of abundant solar energy to chemical fuels. Electrocatalytic water oxidation is challenging due to the multi-step/multi-electron pathway as well as the common degradation of active sites to metal oxos. In collaboration with other groups, we are studying well-defined molecular catalysts, primarily based on abundant first row transition metals such as Cu and Co, including the integration of molecular active sites into conductive carbon materials.

Representative Publications

"Rhodium-Catalyzed Arene Alkenylation Using Only Dioxygen as Oxidant" Zhu, W., Gunnoe, T. B.* ACS Catal. 2020, 10, 11519-11531. DOI: 10.1021/acscatal.0c03439

"Synthesis of Stilbenes by Rhodium-Catalyzed Aerobic Alkenylation of Arenes via C–H Activation" Jia, X., Frye, L. I., Zhu, W., Gu S., Gunnoe, T. B.* J. Am. Chem. Soc. 2020, 142, 10534-10543. DOI: 10.1021/jacs.0c03935

"Use of Ligand Steric Properties to Control the Thermodynamics and Kinetics of Oxidative Addition and Reductive Elimination with Pincer-ligated Rh Complexes" Gu, S., Nielsen, R. J.*, Taylor, K. H., Fortman, G. C., Chen, J., Dickie, D. A., Goddard III, W. A.*, Gunnoe, T. B.* Organometallics 2020, 39, 1917-1933. DOI: 10.1021/acs.organomet.0c00122 (NOTE: List of "Most Read Articles" for Organometallics)

"Advances in Rhodium Catalyzed Oxidative Arene Alkenylation" Zhu, W., Gunnoe, T. B.* Acc. Chem. Res. 2020, 53, 920-936. DOI: 10.1021/acs.accounts.0c00036

"Styrene Production from Benzene and Ethylene Catalyzed by Palladium(II): Enhancement of Selectivity towards Styrene via Temperature Dependent Vinyl Ester Consumption" Jia, X., Foley, A. M., Liu, C., Vaughan, B. A., McKeown, B. A., Zhang, S., Gunnoe, T. B.*  Organometallics 2019, 38, 3532-3541. DOI: 10.1021/acs.organomet.9b00349 (manuscript was selected for the issue cover)

"Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period" Zhu, W., Luo, Z.,  Chen, J., Liu, C., Yang, L., Dickie, D. A., Liu, N., Zhang, S., Davis, R. J., Gunnoe, T. B.* ACS Catalysis 2019, 9, 7457-7475. DOI: 10.1021/acscatal.9b01480

"Catalytic Synthesis of Super Linear Alkenyl Arenes Using a Rh(I) Catalyst Supported by a "Capping Arene" Ligand: Access to Aerobic Catalysis" Chen, J., Nielsen, R. J.*, Goddard III, W. A., McKeown, B. A., Dickie, D. A., Gunnoe, T. B.* J. Am. Chem. Soc. 2018, 140, 17007-17018. DOI: 10.1021/jacs.8b07728

"Catalytic Synthesis of "Super" Linear Alkenyl Arenes Using an Easily Prepared Rh(I) Catalyst" Webster-Gardiner, M. S., Chen, J., Vaughan, B. A., McKeown, B. A., Schinski, W., Gunnoe, T. B.* J. Am. Chem. Soc. 2017, 139, 5474-5480. DOI: 10.1021/jacs.7b01165. This manuscript was highlighted in Chemical and Engineering News 2017, 95(17), 8.

"Organometallic Complexes Anchored to Conductive Carbon for Electrocatalytic Oxidation of Methane at Low Temperature" Joglekar, M., Nguyen, V., Pylypenko, S., Ngo, C., Li, Q., O’Reilly, M.E., Gray, T.S., Hubbard, W.A., Gunnoe, T. B.*, Herring, A. M.*, Trewyn, B.G.*. J. Am. Chem. Soc. 2016, 138, 116-125. This manuscript was highlighted in Chemical and Engineering 2015, 93 (43), 6; featured on cover of J. Am. Chem. Soc., selected for JACS Spotlights). DOI: 10.1021/jacs.5b06392

"A Rhodium Catalyst for Single-Step Styrene Production" Vaughan, B. A., Webster-Gardiner, M. S., Cundari, T. R.*, Gunnoe, T. B.* Science 2015, 348, 421-424. This manuscript was highlighted in Chemical and Engineering News 2015, 93 (17), 26. DOI: 10.1126/science.aaa2260

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