Heui Beom Lee
Verified @gmail.com
RESEARCH, TEACHING, or OTHER INTERESTS
Inorganic Chemistry
Scopus Publications
- Intense NIR absorption in air-stable octahedral complexes of tetravalent Cr, Mn, and Fe supported by a bis(carbene)-amide CNC pincer ligand
Gyeong Min Park, Soohyun Lim, Sang Heon Lee, Sanha Park, Jeewhan Oh, Mi Sook Seo, Sun Hee Kim, Theodore A. Betley, Heui Beom Lee, Yunho Lee
Inorganic Chemistry Frontiers, 2026
Air-stable, formally tetravalent metal complexes supported by a bis(carbene)-amide CNC pincer ligand display significant absorption spanning across the NIR-II region. - Reductive N2 Cleavage and Nitride Insertion Reactivity at Molybdenum Complexes Supported by a Rigid PNP Pincer
Minjun Kim, Jeewhan Oh, Sanha Park, Hankyul Lee, Zee Hwan Kim, Jin Kim, Heui Beom Lee, Jonghoon Choi, Yunho Lee
Angewandte Chemie International Edition, 2025
Metal‐nitride species represent key reactive intermediates in reductive N2 cleavage and functionalization. Toward a better understanding of nitride transfer reactivity, we present a series of Mo‐nitride complexes supported by a rigid diphosphino‐acridane pincer ligand. Notably, the stepwise reduction of a MoIVCl3 complex under N2 allows the isolation of a bridging diazenido intermediate as well as a dinuclear Mo‐nitride species (4) accommodating a bridging N2 moiety. This is the first example of a Mo(IV) nitride‐N2 species, and extensive 15N‐labeling studies were performed to characterize the bridging dinitrogen, diazenido, and nitride moieties. The structure of 4 adopts two orthogonal π‐backbonding interactions between N2 and two structurally rigidified MoIV(N) fragments featuring a filled dπ orbital. Effective π‐backbonding from such a MoIV(N) fragment leads to the isolation of PMe3, CO, and CNtBu substituted analogues. Further, reactivity of the Mo‐nitride species with π‐acidic CO and isocyanide leads to the formation of MoII‐isocyanate and ‐carbodiimide species, respectively. Computational studies suggest that nitride carbonylation proceeds via an associative nitride insertion pathway, encouraging further studies in direct N2 fixation to value‐added products via nitride functionalization. - Reversible CO binding at a nickel complex supported by an ambiphilic PBiP tridentate ligand
Dagyum Yoo, Alexander C. Brannan, Soohyun Lim, Heui Beom Lee, Yunho Lee
Chemical Communications, 2025
A nickel chloride complex supported by a bismuthide diphosphine tridentate ligand reversibly binds CO to afford a nickel dicarbonyl species. - Thermodynamic Hydricity of a Ruthenium CO2 Hydrogenation Catalyst Supported by a Rigid PNP Pincer
Juwon Paik, Jong Hyeak Choe, Sudakar Padmanaban, Misook Seo, Chun-Jae Yoo, Heui Beom Lee, Yunho Lee
Jacs Au, 2025
High Resolution Image Download MS PowerPoint Slide Ruthenium hydride complexes supported by pincer ligands play a crucial role in the catalytic hydrogenation of CO 2 to reduced C 1 chemicals such as formic acid and methanol. Toward a better understanding of their hydride transfer reactivity, knowledge of the underlying thermodynamic hydricity values is deemed critical, but relevant studies remain rare. Herein, we report the experimental thermodynamic hydricity of a new ruthenium CO 2 hydrogenation catalyst ( acri PNP)RuH(CO)(PPh 3 ) ( 1 ) supported by a rigid, acridane-based PNP pincer ligand. We provide the synthesis, structure, and spectroscopic characterization of reaction intermediates involved in formate generation including the anionic dihydride ( 2 ), formate ( 3 ), five-coordinate purple species ( 4 ), and H 2 -bound species ( 5 ). Notably, the effective hydricity of complexes 1 and 2 in THF was determined by the H 2 heterolysis method, revealing values of >52 and 32 kcal/mol, respectively. The corresponding hydricity values of 45–48 kcal/mol for related Ru dihydride complexes supported by neutral PNP pincer ligands highlight the effect of anionic complex charge in promoting stronger hydride donors. CO 2 insertion into the Ru–H bond of the dihydride complex proceeds effectively under ambient conditions, suggesting that base-promoted H 2 heterolysis is the rate-limiting step. Using 1 as a precatalyst, turnover frequencies in the order of 300 h –1 were obtained for formate generation. Broadly, our results provide valuable benchmark thermochemical data for the design of improved CO 2 hydrogenation catalysts. - In Crystallo O2 Cleavage at a Preorganized Triiron Cluster
Heui Beom Lee, Nicholas Ciolkowski, Mackenzie Field, David A. Marchiori, R. David Britt, Michael T. Green, Jonathan Rittle
Journal of the American Chemical Society, 2025
In Nature, the four-electron reduction of O2 is catalyzed at preorganized multimetallic active sites. These complex active sites often feature low-coordinate, redox-active metal centers precisely positioned to facilitate rapid O2 activation processes that obviate the generation of toxic, partially reduced oxygen species. Very few biomimetic constructs simultaneously recapitulate the complexity and reactivity of these biological cofactors. Herein, we report solid-state O2 activation at a triiron(II) active site templated by phosphinimide ligands. Insight into the structure of the O2 reduction intermediates was obtained via in crystallo O2 dosing experiments in conjunction with spectroscopic, structural, magnetic, and computational studies. These data support the in situ formation of an Fe2IIIFeIV-dioxo intermediate upon exposure to O2 that participates in oxygen atom and hydrogen atom transfer reactivity with exogenous substrates to furnish a stable FeIIFe2III-oxo species. Combined, these studies provide an extraordinary level of detail into the dynamics of bond-forming and -breaking processes operative at complex multimetallic active sites. - A stable radical within a N-Co-N core
Anirban Bhandari, Gyeong Min Park, Heui Beom Lee, Sugyeong Hong, Sun Hee Kim, Hye Ryung Byon, Yunho Lee
Chemical Communications, 2024
A stable radical species of an octahedral cobalt complex reveals a delocalized spin density within a N–Co–N core. Its reversible redox interconversion was observed in the presence of an acid or a base. - Coordination Number in High-Spin-Low-Spin Equilibrium in Cluster Models of the S2 State of the Oxygen Evolving Complex
Angela A. Shiau, Heui Beom Lee, Paul H. Oyala, Theodor Agapie
Journal of the American Chemical Society, 2023
The S2 state of the Oxygen Evolving Complex (OEC) of Photosystem II (PSII) shows high-spin (HS) and low-spin (LS) EPR signals attributed to distinct structures based on computation. Five-coordinate MnIII centers are proposed in these species but are absent in available spectroscopic model complexes. Herein, we report the synthesis, crystal structure, electrochemistry, SQUID magnetometry, and EPR spectroscopy of a MnIIIMnIV3O4 cuboidal complex featuring five-coordinate MnIII. This cluster displays a spin ground state of S = 5/2, while conversion to a six-coordinate Mn upon treatment with water results in a spin state change to S = 1/2. These results demonstrate that coordination number, without dramatic changes within the Mn4O4 core, has a substantial effect on spectroscopy. - MnIV 4O4 Model of the S3 Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand
Angela A. Shiau, Heui Beom Lee, Paul H. Oyala, Theodor Agapie
Inorganic Chemistry, 2023
Synthetic complexes provide useful models to study the interplay between the structure and spectroscopy of the different Sn-state intermediates of the oxygen-evolving complex (OEC) of photosystem II (PSII). Complexes containing the MnIV4 core corresponding to the S3 state, the last observable intermediate prior to dioxygen formation, remain very rare. Toward the development of synthetic strategies to stabilize highly oxidized tetranuclear complexes, ligands with increased anion charge were pursued. Herein, we report the synthesis, electrochemistry, SQUID magnetometry, and electron paramagnetic resonance spectroscopy of a stable MnIV4O4 cuboidal complex supported by a disiloxide ligand. The substitution of an anionic acetate or amidate ligand with a dianionic disiloxide ligand shifts the reduction potential of the MnIIIMnIV3/MnIV4 redox couple by up to ∼760 mV, improving stability. The S = 3 spin ground state of the siloxide-ligated MnIV4O4 complex matches the acetate and amidate variants, in corroboration with the MnIV4 assignment of the S3 state of the OEC. - N − H bond dissociation free energy of a terminal iron phosphinimine
Heui Beom Lee, R. David Britt, Jonathan Rittle
Journal of Coordination Chemistry, 2022
The transfer of protons and electrons to metal-ligand multiply-bonded species is a key step in the mechanism of many bond activation processes. In this regard, terminally-bonded phosphinimides (PN) are isolobal analogues of oxos and imidos and should enable late transition metal complexes featuring terminal PNs to engage in H+/e− transfer processes. Recently, we developed a rigid, multidentate PN framework intended to stabilize terminally bonded PN ligands at late, first row transition metals. Herein, we report the synthesis, structure, and spectroscopic characterization of mononuclear FeIII complexes featuring exclusively terminal PN coordination. Magnetic susceptibility and EPR spectroscopic data are consistent with S = 5/2 spin ground states. Proton transfer reactivity both via 1,2-addition across a PN − FeIII moiety and 1,2-elimination from a ferric phosphinimine (PNH) moiety is observed. Hydrogen atom transfer reactivity is observed upon oxidation of the PN − FeIII complex, resulting in formation of a PNH − FeIII species. A combination of electrochemical, pK a measurement, and DFT studies support an N − H bond dissociation free energy of ∼90 kcal/mol for a PNH − FeIII species, and serve to highlight a reactive, transient PN − FeIV species. Combined, our results highlight terminal, late transition metal-PN moieties as redox-active superbases competent for efficient hydrogen atom abstraction processes. Graphical Abstract - Structure and Reactivity of a High-Spin, Nonheme Iron(III)-Superoxo Complex Supported by Phosphinimide Ligands
Charles Winslow, Heui Beom Lee, Mackenzie J. Field, Simon J. Teat, Jonathan Rittle
Journal of the American Chemical Society, 2021
Nonheme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. A further understanding of the Fe-O2 intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O2 exposure of single crystals of a three-coordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally bound Fe-O2 complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous nonheme iron oxygenases. In addition to the apparent stability of this synthetic Fe-O2 complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modeling oxidizing bioinorganic intermediates and green oxidation chemistry. - High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand
Heui Beom Lee, Nicholas Ciolkowski, Charles Winslow, Jonathan Rittle
Inorganic Chemistry, 2021 - CaMn3IVO4 Cubane Models of the Oxygen-Evolving Complex: Spin Ground States S<9/2 and the Effect of Oxo Protonation
Heui Beom Lee, Angela A. Shiau, David A. Marchiori, Paul H. Oyala, Byung‐Kuk Yoo, Jens T. Kaiser, Douglas C. Rees, R. David Britt, Theodor Agapie
Angewandte Chemie International Edition, 2021 - S = 3 Ground State for a Tetranuclear MnIV4O4 Complex Mimicking the S3 State of the Oxygen-Evolving Complex
Heui Beom Lee, David A. Marchiori, Ruchira Chatterjee, Paul H. Oyala, Junko Yano, R. David Britt, Theodor Agapie
Journal of the American Chemical Society, 2020 - Calcium Valence-to-Core X-ray Emission Spectroscopy: A Sensitive Probe of Oxo Protonation in Structural Models of the Oxygen-Evolving Complex
Zachary Mathe, Dimitrios A. Pantazis, Heui Beom Lee, Richard Gnewkow, Benjamin E. Van Kuiken, Theodor Agapie, Serena DeBeer
Inorganic Chemistry, 2019 - Redox Tuning via Ligand-Induced Geometric Distortions at a YMn3O4 Cubane Model of the Biological Oxygen Evolving Complex
Heui Beom Lee, Theodor Agapie
Inorganic Chemistry, 2019 - Synthesis, Electronic Structure, and Spectroscopy of Multinuclear Mn Complexes Relevant to the Oxygen Evolving Complex of Photosystem II
Heui Beom Lee, Paul H. Oyala, Theodor Agapie
Oxygen Production and Reduction in Artificial and Natural Systems, 2019 - Tetranuclear [Mn III Mn 3 IV O 4 ] Complexes as Spectroscopic Models of the S 2 State of the Oxygen Evolving Complex in Photosystem II
Heui Beom Lee, Angela A. Shiau, Paul H. Oyala, David A. Marchiori, Sheraz Gul, Ruchira Chatterjee, Junko Yano, R. David Britt, Theodor Agapie
Journal of the American Chemical Society, 2018 - Tetranuclear Manganese Models of the OEC Displaying Hydrogen Bonding Interactions: Application to Electrocatalytic Water Oxidation to Hydrogen Peroxide
Zhiji Han, Kyle T. Horak, Heui Beom Lee, Theodor Agapie
Journal of the American Chemical Society, 2017 - Ethylene Tetramerization Catalysis: Effects of Aluminum-Induced Isomerization of PNP to PPN Ligands
Alejo M. Lifschitz, Nathanael A. Hirscher, Heui Beom Lee, Joshua A. Buss, Theodor Agapie
Organometallics, 2017 - A CaMn4O2 model of the biological oxygen evolving complex: Synthesis via cluster expansion on a low symmetry ligand
Heui Beom Lee, Emily Y. Tsui, Theodor Agapie
Chemical Communications, 2017 - A ligand field series for the 4f-block from experimental and DFT computed Ce(IV/III) electrochemical potentials
Justin A. Bogart, Andrew J. Lewis, Michael A. Boreen, Heui Beom Lee, Scott A. Medling, Patrick J. Carroll, Corwin H. Booth, Eric J. Schelter
Inorganic Chemistry, 2015 - Structural and electrochemical characterization of a cerium(iv) hydroxamate complex: Implications for the beneficiation of light rare earth ores
Heui Beom Lee, Justin A. Bogart, Patrick J. Carroll, Eric J. Schelter
Chemical Communications, 2014 - Fine-tuning the oxidative ability of persistent radicals: Electrochemical and computational studies of substituted 2-pyridylhydroxylamines
Justin A. Bogart, Heui Beom Lee, Michael A. Boreen, Minsik Jun, Eric J. Schelter
Journal of Organic Chemistry, 2013
