About

Theodore Betley is the Erving Professor of Chemistry and the Director of Graduate Studies at Harvard University's Department of Chemistry and Chemical Biology. His research group specializes in synthetic inorganic chemistry, focusing on designing new complexes capable of activating unreactive chemical bonds. His work involves creating catalysts made from first-row transition elements, where precise control of molecular electronic structure leads to reactivity in organometallic catalysis and small molecule activation. Betley's team has discovered reactive iron-based catalysts for C–H bond functionalization and polynuclear complexes capable of multi-electron small molecule activation reactions. His expertise includes air-free synthesis and a wide array of spectroscopic and theoretical analysis.

Research topics

• Chemistry
• Organic chemistry
• Stereochemistry
• Medicinal chemistry
• Combinatorial chemistry

Selected publications

• Manipulating Terminal Iron-Hydroxide Nucleophilicity through Redox

  Journal of the American Chemical Society · 2026-01-16 · 1 citations

  articleOpen accessSenior author

  I(OH) exhibited electrophilic reactivity at the hydroxo ligand, undergoing radical recombination with carboradicals, akin to the radical recombination reactivity observed in hydroxylation from high-valent iron oxenoids. These results highlight the effect of the oxidation level, ligand electronegativity, and basicity on the resulting nucleophilic/electrophilic character of the terminal Fe-X pair.

  PublisherDOI

• Hydride Transfer Reactivity of an Open-Shell [Fe ₃ H] ⁻ Cluster

  Journal of the American Chemical Society · 2025-10-10 · 1 citations

  articleSenior authorCorresponding

  We report herein the synthesis and reactivity of the high-spin iron-hydride cluster [K(C222)][(tbsL)Fe3(μ3–H)]. Direct hydride transfer reaction attempts led to cluster reduction to afford the anionic cluster [(tbsL)Fe3]−, whereas metathesis using phenylsilane and an alkoxide-bound cluster (e.g., [(tbsL)Fe3(μ3–OMe)]−) afforded the targeted hydride-bearing cluster [K(C222)][(tbsL)Fe3(μ3–H)]. The hydride cluster was verified using both solution (e.g., NMR, cyclic voltammetry) and solid-state techniques (e.g., 57Fe Mössbauer, X-ray crystallography). The anionic hydride was shown to be reactive with unsaturated small molecule substrates (e.g., aldehydes, isonitriles, alkynes) to afford their cooperatively bound reduction products. Furthermore, the anionic hydride cluster was shown to be a viable catalyst for hydrosilylation of aldehyde substrates, converting benzyl and alkyl aldehydes to their corresponding silylethers.

  PublisherDOI

• Intense NIR absorption in air-stable octahedral complexes of tetravalent Cr, Mn, and Fe supported by a bis(carbene)-amide CNC pincer ligand

  Inorganic Chemistry Frontiers · 2025-12-17

  article

  Air-stable, formally tetravalent metal complexes supported by a bis(carbene)-amide CNC pincer ligand display significant absorption spanning across the NIR-II region.

  PublisherDOI

• Synthesis of a Stable Tricobalt Carbide Cluster

  Journal of the American Chemical Society · 2025-05-29 · 2 citations

  articleSenior authorCorresponding

  We report the synthesis and characterization of the anionic tricobalt carbide cluster [(FtbsL)Co3(μ3–C)]−. The source of the carbide ligand is a phosphorus ylide (R2MePCH2; R = Me, Ph) which substitutes pyridine in the all-cobalt(II) cluster (FtbsL)Co3(py) to afford the ylide adduct (FtbsL)Co3(CH2PMeR2). Deprotonation affords the anionic diylide cluster [(FtbsL)Co3(κ2-η1:η1–(CH2)2PR2)]− which eliminates MePR2 upon heating to furnish the anionic methylidyne cluster [(FtbsL)Co3(μ3–CH)]−. Oxidation of the anionic methylidyne complex with ferrocenium hexafluorophosphate generates the diamagnetic methylidyne complex (FtbsL)Co3(μ3–CH). The methylidyne ligand can be deprotonated with Li- or KN(SiMe3)2 to afford carbide complexes (FtbsL)Co3(μ4–C)Li(OEt2) or [K(C222)][(FtbsL)Co3(μ3–C)], respectively. Isotopic enrichment of the carbide with 13C reveals downfield-shifted 13C NMR chemical shifts (δ/ppm) of 389, Co3(μ3–CH); 731, Co3(μ4–CLi); and 769, Co3(μ3–C)−; the latter of which is the most downfield resonance for a transition metal carbide reported to date.

  PublisherDOI

• Occupancy Determination from Resonant X-ray Diffraction

  Inorganic Chemistry · 2025-02-06 · 1 citations

  articleSenior authorCorresponding

  We analyze the effect of integrated resolution, data scaling, structural refinement, and crystal symmetry on the extracted scattering perturbations and their uncertainties for anomalous (resonant) X-ray diffraction on mixed-metal molecular clusters. We probe the metal constituency, substitutional homogeneity, and positional disorder of both biased and unbiased ligand environments. Anomalous X-ray diffraction studies were conducted on (FtbsL)Zn2Ni(py) (1), [K(C222)][(FtbsL)Zn2Ni] (2), and [K(THF)3][(FtbsL)Zn2Ni(NAd)] (3). Analysis of diffraction data collected at energies along the Ni and Zn K-edges on [Zn2Ni] clusters reveals data resolution, and the accuracy of the structural model greatly impacts the resonant scattering factors (f′, f″) and their uncertainties. Occupancy studies on all three clusters were conducted in three ways and compared: (i) using the f′ values of each metal site refined from diffraction data collected at energies along the Ni and Zn K-edges; (ii) using the f′ value of each metal site refined from diffraction data collected with in-house, Cu Kα radiation; and (iii) refining each metal site as a Zn/Ni disordered pair and fixing the relative Zn-to-Ni occupancies as 2:1 across the core with supporting spectroscopic evidence from scanning electron microscope energy-dispersive spectroscopy. First, we observe highly ordered structural compositions, even when statistical mixing was anticipated; and second, we discovered that in-house X-ray diffraction collection was as precise in composition determination as synchrotron sources for this study.

  PublisherDOI

• An Open-Shell Fe^IV Nitrido

  Journal of the American Chemical Society · 2025-01-20 · 7 citations

  articleSenior authorCorresponding

  We report the photogeneration and characterization of an open-shell, terminal iron nitrido (EmL)Fe(N) using a sterically encumbered dipyrrin ligand environment. The Fe–N distance in the solid-state, zero-field 57Fe Mössbauer spectrum, and computational analysis are consistent with a triplet electronic ground state of the iron nitrido. Notably, the attenuation of Fe–N multiple bond character through occupying π*Fe–N enables (i) primary C(sp3)–H amination, (ii) H2 cleavage, (iii) aromatic C–C cleavage, and (iv) photocatalytic N-atom transfer reactivity. These modes of reactivity have not previously been observed in low-spin Fe(N) analogues.

  PublisherDOI

• Catalyst design for small molecule activation of energy consequence

  2024-05-03

  reportOpen access1st authorCorresponding

  This project targets the conversion of ubiquitous small molecules (e.g. NO, CO, H₂O) into viable precursors to synthetic fuels. Current state of the art catalyst design has not directly targeted transition metal complexes capable of mediating the multi-electron redox processes necessary to reduce the overpotential (energy loss) required achieve efficient activation of small molecule substrates. In this vein, a new strategy has been developed for the assembly of polynuclear architectures; allowing for the construction of tunable polymetallic centers that assemble easily within a pre-organized template (conferring stability, selectivity and tunability) that can effect multi-electron redox processes for reactions. Catalyst development has commenced with the following target design elements: (1) catalysts featuring multiple transition metal ions in the same reaction space to greatly expand accessible molecular redox capabilities; (2) catalysts are assembled in a polynucleating ligand framework that permits control over the cluster morphology as well as the local steric and electronic environment of the transition metal ions within the cluster. The high-tunability of the catalyst composition (metal content) and geometric flexibility has permitted a rigorous assessment of electronic-structure-to-function relationship to be developed, further guiding synthetic efforts to realize more potent catalysts. The numerous permutations possible showcase the high degree of generality to this approach with many synthetic handles to tune redox and reaction chemistry. Trinuclear complexes have been synthesized featuring homo- and hetero-trinuclear cores featuring a variety of first row transition metal ions (Cr→Ni). The molecular clusters have been shown to successfully mediate multi-electron redox processes in a cooperative fashion without requiring strong chemical reductants or oxidants. The reactive molecular complexes are being utilized to activate and breakdown the robust bonds within typical waste stream small molecules (e.g., greenhouse gases) and convert them into value-added commodity chemicals. Ultimately, the catalysts developed by this approach will be required to convert energy acquired via renewable resources (e.g., solar or wind) into synthetic fuels as an energy storage mechanism.

  PublisherDOI

• C–H Insertion from Isolable Copper Benzylidenes

  Journal of the American Chemical Society · 2024-10-23 · 6 citations

  articleSenior authorCorresponding

  Despite the utility of copper catalysts for the insertion of carbene moieties into C–H bonds, the copper carbene intermediate often invoked in these transformations has not been isolated. Herein, we describe the synthesis and structural characterization of a series of copper benzylidenes utilizing the sterically encumbered dipyrrin ligand (EmL)H. These isolated copper carbenes demonstrate intramolecular insertion into the primary C(sp3)–H bond of the ligand (EmL)H and intermolecular insertion into ethereal and allylic C–H bonds. The copper carbenes isolated are best described as Cu(I) carbene adducts akin to canonical Fischer carbenes, given their diamagnetic ground state and electrophilic carbene reactivity. Furthermore, the insertion chemistry can be rendered catalytic utilizing a more sterically exposed dipyrrin ligand (ArFL)H. The ability to isolate and observe stoichiometric C–H insertion and olefin cyclopropanation from well-characterized copper benzylidenes illuminates their viability as catalytic intermediates and their participation in potential catalyst deactivation pathways.

  PublisherDOI

• Composition Determination of Heterometallic Trinuclear Clusters via Anomalous X-ray and Neutron Diffraction

  Journal of the American Chemical Society · 2024-10-26 · 3 citations

  articleSenior authorCorresponding

  Anomalous X-ray diffraction (AXD) and neutron diffraction can be used to crystallographically distinguish between metals of similar electron density. Despite the use of AXD for structural characterization in mixed metal clusters, there are no benchmark studies evaluating the accuracy of AXD toward assessing elemental occupancy in molecules with comparisons with what is determined via neutron diffraction. We collected resonant diffraction data on several homo and heterometallic clusters and refined their anomalous scattering components to determine metal site occupancies. Theoretical resonant scattering terms for Fe0, Co0, and Zn0 were compared against experimental values, revealing theoretical values are ill-suited to serve as references for occupancy determination. The cluster featuring distinct cation and anion metal compositions [CoCp2*][(tbsL)Fe3(μ3–NAr)] was used to assess the accuracy of different f′ references for occupancy determination (f′theoretical ± 15–17%; f′experimental ± 10%). This methodology was applied toward calculating the occupancy of three different clusters: (tbsL)Fe2Zn(py) (6), (tbsL)Fe2Zn(μ3–NAr)(py) (7), and [CoCp*2][(tbsL)Fe2Zn(μ3–NAr)] (8). The first two clusters maintain 100% Fe/Zn site isolation, whereas 8 showed metal mixing within the sites. The large crystal size of 8 enabled collection of neutron diffraction data which was compared against the results found with AXD. The ability of AXD to replicate the metal occupancies as determined by neutron diffraction supports the AXD occupancy methodology developed herein. Furthermore, the advantages innate to AXD (e.g., smaller crystal sizes, shorter collection times, and greater availability of synchrotron resources) versus neutron diffraction further support the need for its development as a standard technique.

  PublisherDOI

• Integrating fundamental concepts with practical skills: consolidating small-molecule crystallography education

  Journal of Applied Crystallography · 2024-12-24 · 5 citations

  articleOpen accessSenior author

  A comprehensive educational strategy designed to make small-molecule crystallography more accessible for students at various academic levels is described. By integrating hands-on laboratory visits, structured courses and advanced application training, we cultivate a deep understanding of fundamental crystallographic concepts while fostering practical skills. This strategy also aims to inspire novice learners, building their confidence and interest in structural science. Our approach demystifies complex concepts through real-world examples and interactive case-learning modules, enabling students to proficiently apply crystallography in their research. The resulting educational impact is evident in numerous publications from undergraduates, scholarship awards to graduates and successful independent research projects, highlighting the effectiveness of our programme in inspiring the next generation of chemical crystallographers.

  PublisherOA PDFDOI

Recent grants

• Polynuclear iron complexes as functional mimics of the nitrogenase FeMo-cofactor

  NIH · $2.8M · 2011–2022

• CAS: Collaborative Research: Electronic Structure/Function Relationships Underpinning Atom Transfer Reactivity

  NSF · $361k · 2023–2026

• MRI: Acquisition of Single-Crystal Diffractometer for Small Molecule Crystallography and Cryosystem

  NSF · $301k · 2022–2025

• CAREER: Iron mediated catalytic C-H bond functionalization

  NSF · $600k · 2010–2015

• Correlation of electronic structure to iron catalyzed C-H bond functionalization

  NIH · $1.3M · 2015–2019

Frequent coauthors

• Shao‐Liang Zheng

  Harvard University

  155 shared

• Diana A. Iovan

  Virginia Tech

  79 shared

• Jonas C. Peters

  70 shared

• Yunjung Baek

  59 shared

• E.R. King

  46 shared

• Raúl Hernández Sánchez

  Rice University

  45 shared

• Kurtis M. Carsch

  University of California, Berkeley

  43 shared

• Kyle M. Lancaster

  Cornell University

  42 shared

Labs

• The Betley LabPI

Awards & honors

• Technology Review top 35 US technological innovators
• NSF Early Career Award
• DOE Early Career Award
• DOD Early Career Award