About

T. Brent Gunnoe is the Commonwealth Professor of Chemistry with research interests spanning inorganic and organic chemistry, focusing on the development of efficient synthetic methods, transition metal complexes, and catalysis. His work emphasizes the preparation and characterization of new transition metal complexes capable of activating organic molecules for novel reactivity, with the goal of designing single-site catalysts that underpin new synthetic methodologies. His research aims to address economic and environmental challenges in the chemical industry by exploring fundamental inorganic and organometallic chemistry to develop catalysts for energy-related processes, large-scale chemical synthesis, and fine chemicals. Gunnoe's group investigates catalytic processes such as the selective breaking of C–H bonds, catalytic C–C bond formation, and the conversion of light alkanes like methane, ethane, and propane into useful products like alcohols. He also studies electrocatalytic water oxidation as part of efforts to convert solar energy into chemical fuels, focusing on molecular catalysts based on abundant transition metals like copper and cobalt. His contributions include the development of catalysts for aerobic alkenylation, styrene production, and electrocatalytic oxidation, with his work recognized through numerous publications and highlights in the scientific community. His research is driven by fundamental inorganic and organometallic chemistry principles, aiming to create more efficient, sustainable catalytic processes for energy and chemical production.

Research topics

• Chemistry
• Organic chemistry
• Medicinal chemistry
• Combinatorial chemistry
• Physical chemistry
• Chemical physics
• Inorganic chemistry
• Chemical engineering
• Nanotechnology
• Materials science
• Computational chemistry

Selected publications

• Mechanistic Studies of Alkyl Chloride Acetoxylation by Pt–Sb Complexes

  Organometallics · 2025-02-20 · 5 citations

  articleOpen accessSenior authorCorresponding

  The bis-acetate complexes (SbQ3)Pt(OAc)2 (1) and (SbQ2Ph)Pt(OAc)2 (2) (Q = 8-quinolinyl) were used to study C–Cl acetoxylation of 1,2-dichloroethane (DCE) to generate 2-chloroethyl acetate and the complexes (SbQ3)PtCl2 (1b) and (SbQ2Ph)PtCl2 (2b), respectively. The first acetoxylation step produced the intermediates (SbQ3)Pt(Cl)(OAc) (1a) and (SbQ2Ph)Pt(Cl)(OAc) (2a). The reaction was studied using pseudo first order kinetics (excess DCE) in order to compare the rates of reaction of 1 and 2, which revealed that kobs = 2.44(6) × 10–4 s–1 for 1 and 0.51(2) × 10–4 s–1 for 2. The intermediate 1a was synthesized independently, and the solid-state structure was determined using single crystal X-ray diffraction. A non-Sb containing control complex, (tbpy)Pt(OAc)2 (3) (tbpy = 4,4′-di-tert-butyl-2,2′bipyridine), was studied for the acetoxylation of DCE to form (tbpy)Pt(Cl)(OAc) with kobs = 0.46(1) × 10–4 s–1. Density Functional Theory (DFT) calculations were used to examine possible Pt-mediated mechanisms for the reactions of 1, 2, or 3 with DCE. The lowest energy calculated substitution mechanism occurs with nucleophilic attack by the Pt center on the C−Cl bond followed acetate reaction with the Pt−C bond. However, close in energy and potentially also a viable mechanism is a direct substitution mechanism where the coordinated acetate anion directly reacts with the C−Cl bond of DCE. In addition, the rate of acetoxylation for complex 1 in heated dichloromethane-d2 and chloroform-d was determined (0.43(1) × 10–4 s–1 for dichloromethane-d2 and 0.37(1) × 10–4 s–1 for chloroform-d) and compared to the rate of acetoxylation of DCE.

  PublisherDOI

• Polymer Binder Blends Stabilize Alkaline Hydrogen Evolution by Heterogenized Molecular Phen-Based Cobalt Electrocatalysts through Coordination and Environmental Control

  Journal of the American Chemical Society · 2025-03-11 · 8 citations

  articleOpen access

  With the increase in greenhouse gas emissions and their detrimental effect on the environment, there is a push to develop a renewable way to produce H2, a fuel source that has nonharmful byproducts, unlike traditional methods of energy production. Alkaline water electrolysis has seen increasing focus as a viable way to produce H2, but efficient and stable electrocatalysts are required to facilitate this process. Here, a heterogenized Co(II) phenanthroline-based complex for the production of H2 from alkaline water is disclosed. Activity was improved by considering the role of axial Co ligation and the reaction environment created by the polymer binder in the catalyst inks by using variable ratios of Nafion and poly-4-vinylpyridine (P4VP). A ratio of 1:1 Nafion:P4VP was found to have the highest stability, and Co nanoparticle formation was not observed when P4VP was included as part of the binder mixture. The activity and stability enhancement could not be replicated by the addition of molecular pyridine or the use of poly-2-vinylpyridine, which is sterically prevented from coordinating to Co. The increased electrochemical performance caused by the inclusion of Nafion as part of the polymer binder is attributed to a role in mass transfer to and from the Co active site during catalysis, complementing the stabilizing effect of P4VP on the molecular active site.

  PublisherOA PDFDOI

• Rhodium‐Catalyzed Oxidative Alkenylation of Naphthalene: Factors That Influence Reaction at the β‐ versus α‐Position

  ChemCatChem · 2025-04-10 · 1 citations

  articleOpen accessSenior authorCorresponding

  Abstract The catalyst precursor [(η 2 ‐C 2 H 4 ) 2 Rh(μ‐OAc)] 2 and in situ oxidant Cu(OPiv) 2 (OPiv = t ‐BuCOO – ) convert naphthalene and olefins (i.e., ethylene and propylene) to alkenylnaphthalenes. Under all reaction conditions tested, the functionalization is selective for the β‐position of naphthalene with the highest observed β:α ratio >20:1. The β‐selectivity is catalyst controlled, but oxidant identity, ethylene pressure, and olefin identity influence the ratio of β‐alkenylation to α‐alkenylation. The concentration of HOPiv and naphthalene do not have an effect on the β:α ratio under the reaction conditions tested. Arenes similar to naphthalene (i.e., o‐ xylene and 1,2,3,4‐tetrahydronaphthalene) give quantitative selectivity for alkenylation at the position β to the substituent. Using propylene as the olefin for naphthalene alkenylation, the β:α ratio is 32(7):1. and the anti‐Markovnikov to Markovnikov ratio is 16(2):1.

  PublisherOA PDFDOI

• A Change in C–H Activation Mechanism: Experimental and Computational Investigations of Rh-Catalyzed Disubstituted Benzene Functionalization

  Organometallics · 2025-10-29 · 1 citations

  articleOpen accessSenior authorCorresponding

  We report the ethenylation of 1,3- and 1,2-disubstituted benzenes using [(η2-C2H4)2Rh(μ-OAc)]2 as a catalyst precursor and Cu(OPiv)2 as the oxidant. The regioselectivity of alkenylation for 1,3-disubstituted benzenes produces 3,5-disubstituted styrene products, while the alkenylation of 1,2-disubstituted benzenes produces 3,4-disubstituted styrene products. The rate of alkenylation is influenced by steric and electronic factors based on the substituents of the benzene unit. In all cases, 1,2-disubstituted benzenes react faster than 1,3-disubstituted benzenes, with a rate difference that is from 2 times up to >70 times more rapid for 1,2-disubstituted substrates. This is likely due to the difference in the number of accessible C–H bonds based on the steric protection of C–H bonds adjacent to functionality. Furthermore, the rate of alkenylation is influenced by the arene substituent electronics. The rates of alkenylation for 1,2-disubstituted benzenes follow the trend OMe > Me > CF3 > Cl, while for 1,3-disubstituted benzenes the trend is CF3 > Cl > Me > OMe. Using quantum mechanics DFT calculations, we found that the C–H activation step can occur by two different mechanisms. The electronic properties of substituents on the arene ring change the preferred C–H bond-breaking mechanism for 1,2-disubstituted and 1,3-disubstituted benzenes.

  PublisherDOI

• Synthesis of Quinoline-Based Rh–Sb Complexes: Inhibition of Halide Transfer to Access a Rh→Sb Z-Type Interaction

  Organometallics · 2025-08-01 · 2 citations

  articleOpen accessSenior authorCorresponding

  We report the synthesis of Rh–Sb complexes using high valent Sb ligands, Q3SbCl2 (1, Q = 8-quinolinyl) and Q3SbF2 (2), from the low valent Rh precursor [(CO)2Rh(μ-Cl)]2 to afford the complexes [(κ4-Q3SbCl)Rh(CO)Cl][(CO)2RhCl2] (3) and (κ4-Q3SbF2)Rh(CO)Cl (4), respectively. The reaction of 1 with [(CO)2Rh(μ-Cl)]2 results in the transfer of chloride from Sb to Rh to give the ion pair 3 with a Rh–Sb bond for the cation that, according to computational analysis, has some covalent character. Replacing Sb–Cl with Sb–F bonds (i.e., compound 2) inhibited halide transfer and allowed formation of 4 with a Rh→Sb interaction that has more Z-type character than the Rh–Sb bond for complex 3. Molecular orbital and localized orbital bonding analyses are consistent with the proposed Rh→Sb interaction of 4 being more Z-type in character.

  PublisherDOI

• Covalent Bonding Between Ir and High-Oxidation State Sb Constrained by Quinoline Scaffolds

  Inorganic Chemistry · 2025-08-14 · 2 citations

  articleOpen accessSenior authorCorresponding

  From the reaction of a high-valent Sb(V) proligand with a low-valent Ir(I) precursor in acetonitrile, a bimetallic Sb–Ir complex was isolated in which one of the quinoline groups inverted such that it is N-coordinated to Sb and C-coordinated to Ir. The new Sb–Ir complex has a unique structure containing the shortest reported Sb–Ir bond (2.51502(18) Å). Our combined experimental and computational studies indicate pronounced covalent character for the Sb–Ir bond. Based on the covalent bonding, the complex more closely resembles Sb(IV)–Ir(II) species rather than Sb(V)–Ir(I) and thus results in an Ir center with poor π-basicity, particularly toward the position trans to Sb.

  PublisherOA PDFDOI

• Hexa-Fe(III) Carboxylate Complexes Facilitate Aerobic Hydrocarbon Oxidative Functionalization: Rh Catalyzed Oxidative Coupling of Benzene and Ethylene to Form Styrene

  ACS Catalysis · 2024-06-24 · 7 citations

  articleOpen accessSenior authorCorresponding

  Fe(II) carboxylates react with dioxygen and carboxylic acid to form Fe6(μ–OH)2(μ3–O)2(μ–X)12(HX)2 (X = acetate or pivalate), which is an active oxidant for Rh-catalyzed arene alkenylation. Heating (150–200 °C) the catalyst precursor [(η2–C2H4)2Rh(μ–OAc)]2 with ethylene, benzene, Fe(II) carboxylate, and dioxygen yields styrene >30-fold faster than the reaction with dioxygen in the absence of the Fe(II) carboxylate additive. It is also demonstrated that Fe6(μ–OH)2(μ3–O)2(μ–X)12(HX)2 is an active oxidant under anaerobic conditions, and the reduced material can be reoxidized to Fe6(μ–OH)2(μ3–O)2(μ–X)12(HX)2 by dioxygen. At optimized conditions, a turnover frequency of ∼0.2 s–1 is achieved. Unlike analogous reactions with Cu(II) carboxylate oxidants, which undergo stoichiometric Cu(II)-mediated production of phenyl esters (e.g., phenyl acetate) as side products at temperatures ≥150 °C, no phenyl ester side product is observed when Fe carboxylate additives are used. Kinetic isotope effect experiments using C6H6 and C6D6 give kH/kD = 3.5(3), while the use of protio or monodeutero pivalic acid reveals a small KIE with kH/kD = 1.19(2). First-order dependencies on Fe(II) carboxylate and dioxygen concentration are observed in addition to complicated kinetic dependencies on the concentration of carboxylic acid and ethylene, both of which inhibit the reaction rate at a high concentration. Mechanistic studies are consistent with irreversible benzene C–H activation, ethylene insertion into the formed Rh–Ph bond, β–hydride elimination, and reaction of Rh–H with Fe6(μ–OH)2(μ3–O)2(μ–X)12(HX)2 to regenerate a Rh-carboxylate complex.

  PublisherOA PDFDOI

• Carbodicarbene‐Stibenium Ion‐Mediated Functionalization of C(sp³)−H and C(sp)−H Bonds

  Angewandte Chemie International Edition · 2024-09-09 · 12 citations

  articleOpen accessCorresponding

  Abstract Main‐group element‐mediated C−H activation remains experimentally challenging and the development of clear concepts and design principles has been limited by the increased reactivity of relevant complexes, especially for the heavier elements. Herein, we report that the stibenium ion [( py CDC)Sb][NTf 2 ] 3 ( 1 ) ( py CDC=bis‐pyridyl carbodicarbene; NTf 2 =bis(trifluoromethanesulfonyl)imide) reacts with acetonitrile in the presence of the base 2,6‐di‐ tert ‐butylpyridine to enable C(sp 3 )−H bond breaking to generate the stiba‐methylene nitrile complex [( py CDC)Sb(CH 2 CN)][NTf 2 ] 2 ( 2 ). Kinetic analyses were performed to elucidate the rate dependence for all the substrates involved in the reaction. Computational studies suggest that C−H activation proceeds via a mechanism in which acetonitrile first coordinates to the Sb center through the nitrogen atom in a κ 1 fashion, thereby weakening the C−H bond which can then be deprotonated by base in solution. Further, we show that 1 reacts with terminal alkynes in the presence of 2,6‐di‐ tert ‐butylpyridine to enable C(sp)−H bond breaking to form stiba‐alkynyl adducts of the type [( py CDC)Sb(CCR)][NTf 2 ] 2 ( 3 a – f ). Compound 1 shows excellent specificity for the activation of the terminal C(sp)−H bond even across alkynes with diverse functionality. The resulting stiba‐methylene nitrile and stiba‐alkynyl adducts react with elemental iodine (I 2 ) to produce iodoacetonitrile and iodoalkynes, while regenerating an Sb trication.

  PublisherOA PDFDOI

• Carbodicarbene‐Stibenium Ion‐Mediated Functionalization of C(sp ³ )−H and C(sp)−H Bonds

  Angewandte Chemie · 2024-09-08 · 2 citations

  article

  Abstract Main‐group element‐mediated C−H activation remains experimentally challenging and the development of clear concepts and design principles has been limited by the increased reactivity of relevant complexes, especially for the heavier elements. Herein, we report that the stibenium ion [( py CDC)Sb][NTf 2 ] 3 ( 1 ) ( py CDC=bis‐pyridyl carbodicarbene; NTf 2 =bis(trifluoromethanesulfonyl)imide) reacts with acetonitrile in the presence of the base 2,6‐di‐ tert ‐butylpyridine to enable C(sp 3 )−H bond breaking to generate the stiba‐methylene nitrile complex [( py CDC)Sb(CH 2 CN)][NTf 2 ] 2 ( 2 ). Kinetic analyses were performed to elucidate the rate dependence for all the substrates involved in the reaction. Computational studies suggest that C−H activation proceeds via a mechanism in which acetonitrile first coordinates to the Sb center through the nitrogen atom in a κ 1 fashion, thereby weakening the C−H bond which can then be deprotonated by base in solution. Further, we show that 1 reacts with terminal alkynes in the presence of 2,6‐di‐ tert ‐butylpyridine to enable C(sp)−H bond breaking to form stiba‐alkynyl adducts of the type [( py CDC)Sb(CCR)][NTf 2 ] 2 ( 3 a – f ). Compound 1 shows excellent specificity for the activation of the terminal C(sp)−H bond even across alkynes with diverse functionality. The resulting stiba‐methylene nitrile and stiba‐alkynyl adducts react with elemental iodine (I 2 ) to produce iodoacetonitrile and iodoalkynes, while regenerating an Sb trication.

  PublisherDOI

• Highly Anti-Markovnikov Selective Oxidative Arene Alkenylation Using Ir(I) Catalyst Precursors and Cu(II) Carboxylates

  Organometallics · 2024-03-20 · 7 citations

  articleOpen accessSenior authorCorresponding

  The Ir(I) complex [Ir(μ-Cl)(coe)2]2 (coe = cis-cyclooctene) is a catalyst precursor for benzene alkenylation using Cu(II) carboxylate salts. Using [Ir(μ-Cl)(coe)2]2, propenylbenzenes are formed from the reaction of benzene, propylene, and CuX2 (X = acetate, pivalate, or 2-ethylhexanoate). The Ir-catalyzed reactions selectively produce anti-Markovnikov products, trans-β-methylstyrene, cis-β-methylstyrene, and allylbenzene, along with minor amounts of the Markovnikov product, α-methylstyrene. The selectivity for the anti-Markovnikov products changed as the reaction progressed. For example, in a reaction that uses 240 equiv of Cu(OHex)2 (related to Ir), the selectivity for the anti-Markovnikov products increases from 18:1 at 3 h to 42:1 at 42 h with 30 psig of propylene at 150 °C. Studies of product stability have revealed that the increase in the selectivity for anti-Markovnikov products is not the result of an isomerization process or the selective decomposition of specific products. Rather, the change in selectivity correlates with the ratio of Cu(II) to Cu(I) in the solution, which decreases as the reaction progresses. We propose that the identity of the active catalyst changes as Cu(I) is accumulated, resulting in the formation of an active catalyst that is more selective for anti-Markovnikov products. Using a 4:1 Cu(I)/Cu(II) ratio at the start of the reaction, a 65(3):1 anti-Markovnikov/Markovnikov ratio is observed.

  PublisherOA PDFDOI

Recent grants

• Ligand Controlled Redox Catalysis with Late Transition Metal Complexes

  NSF · $500k · 2021–2024

• 1,2-Addition of C-H Bonds Across Metal-Heteroatom Bonds: Study of Reactions Central to Hetero-Functionalization of C-H Bonds

  NSF · $375k · 2009–2013

• MRI: Acquisition of X-Ray Single-Crystal CCD Diffractometer at the University of Virginia

  NSF · $209k · 2011–2014

• Development of Hybrid Solid Materials for Stable Molecular Oxygen Anodes

  NSF · $725k · 2018–2022

• New Catalysts for Hydrocarbon Partial Oxidation

  NSF · $470k · 2018–2022

Frequent coauthors

• Thomas R. Cundari

  University of North Texas

  331 shared

• Jeffrey L. Petersen

  West Virginia University

  214 shared

• Diane A. Dickie

  106 shared

• Paul D. Boyle

  95 shared

• William A. Goddard

  California Institute of Technology

  92 shared

• N.A. Foley

  Drexel University

  83 shared

• Michal Sabat

  University of Virginia

  81 shared

• Marty Lail

  80 shared

Labs

• Gunnoe Research LabPI

Awards & honors

• NSF Graduate Research Fellowship
• Energy Research Partnership with Max Planck Society to Boost…