Research Projects

Multifunctional Ligands

We are investigating redox-active ligands that also play an active role in substrate binding via metal-ligand cooperative (MLC) reactions. The goal is to couple both types of ligand-centered reactivity to promote new catalytic transformations, and fundamental studies are aimed at identifying how chemical binding at redox-active ligands affects their redox properties.

Recent Publications: Spielvogel, K. D.;* Stumme, N. C.;* Fetrow, T. V.; Wang, L.; Luna, J. A.; Keith, J. M.; Shaw, S. K.; Daly, S. R. "Quantifying Variations in Metal-Ligand Cooperative Binding Strength with Cyclic Voltammetry and Redox-Active Ligands." Inorg. Chem. 2022, 61, 2391–2401 (link). *Equal contributions.

Spielvogel, K. D.;* Luna, J. A.;* Loria, S. M.; Weisburn, L. P.; Stumme, N. C.; Ringenberg, M. R.; Durgaprasad, G.; Keith, J. M.; Shaw, S. K.; Daly, S. R. "The Influence of Multisite Metal-Ligand Cooperativity on the Redox Activity of Noninnocent N₂S₂ Ligands." Inorg. Chem. 2020, 59, 10845–10853 (link). *Equal contributions.

Spielvogel, K. D.; Coughlin, E. J.; Petras, H.; Luna, J. A.; Benson, A.; Donahue, C. M.; Kibasa, A.; Lee, K.; Salacinski, R.; Bart, S. C.; Shaw, S. K.; Shepherd, J.; Daly, S. R. "The Influence of Redox-Innocent Donor Groups in Tetradentate Ligands Derived from o-Phenylenediamine: Electronic Structure Investigations with Nickel." Inorg. Chem. 2019, 58, 12756-12774 (link).

Cooperative Ligand-Centered Reactivity

We are developing triaminoborane-bridged diphosphorus ligands called TBDPhos that participate in cooperative ligand-centered reactivity while bound to transitions metals. TBDPhos ligands are capable of selectively adding H-X across the bridghead N-B bond on the TBD backbone while bound to different transition metals. The reactions appear to proceed via formation of ligand-centered borenium ions and require cooperative participation of both N and B to overcome low boron Lewis acidity in the TBD backbone. We are currently exploring the mechanism of these ligand-centered reactions and investigating their applications.

Recent Publications: Skaria, M.; Culpepper, J. D.; Daly, S. R. "Leveraging Metal and Ligand Reactive Sites for One Pot Reactions: Ligand-Centered Borenium Ions for Tandem Catalysis with Palladium." Chem. Eur. J. 2022, 28, e202201791 (link).

Culpepper, J. D.; Lee, K.; Portis, W.; Swenson, D. C.; Daly, S. R. "Fluorination and Hydrolytic Stability of Water-Soluble Platinum Complexes with a Borane-Bridged Diphosphoramidite Ligand." Dalton Trans. 2022, 51, 12895-12903 (link).

Lee, K.; Lai, P.; Parveen, R.; Donahue, C. M.; Wymore, M. M.; Massman, B. A.; Vlaisavljevich, B.; Teets, T. S.; Daly, S. R. "Modifying the Luminescent Properties of a Cu(I) Diphosphine Complex Using Ligand-Centered Reactions in Single Crystals." Chem. Commun. 2020, 56, 9110-9113 (link). Invited submission for Emerging Investigators Issue.

Lee, K.; Culpepper, J. D.; Parveen, R.; Swenson, D. C.; Vlaisavljevich, B.; Daly, S. R. "Modifying Phosphorus(III) Substituents to Activate Remote Ligand-Centered Reactivity in Triaminoborane Ligands." Organometallics 2020, 39, 2526–2533 (link).

Lee, K.; Kim, C.; Buckley, J. L.; Vlaisavljevich, B.; Daly, S. R. " Isolation of Ligand-Centered Borocations in Molybdenum Complexes Containing a Triaminoborane-Bridged Diphosphorus Ligand." Dalton Trans. 2019, 48, 3777-3785 (link). Invited submission for themed web collection: Inorganic Chemistry of the p-Block Elements.

Lanthanide and Trivalent Actinide Chemistry

The separation of minor actinides (namely Am and Cm) and lanthanides is a critical step proposed in several advanced nuclear fuel cycles, yet it is a difficult separation owing to their similar chemical properties and redox chemistry dominated by a common +3 oxidation state. However, despite these similarities, it has been shown that so-called "soft-donor" ligands (especially those containing N and S) are capable of discriminating between these 4f and 5f elements. Our group has been focused on developing conventional and unconventional soft-donor ligands such as borohydrides to evaluate the fundamental relationship between metal-ligand covalency and soft-donor binding affinity to f-metal ions in solution.

Recent Publications: Fetrow, T. V.;* Zgrabik, J.;* Bhowmick, R.; Eckstrom, F. D.; Crull, G.; Vlaisavljevich, B.; Daly, S. R. "Quantifying the Influence of Covalent Metal-Ligand Bonding on Differing Solution Reactivity of Trivalent Uranium and Lanthanide Complexes." Angew. Chem., Int. Ed. 2022, 61, e202211145 (link). *Equal contributions.

Fetrow, T. V.; Grabow, J. P.; Leddy, J.; Daly, S. R. "Convenient Syntheses of Trivalent Uranium Starting Materials without Uranium Metal." Inorg. Chem. 2021, 60, 7593–7601 (link).

Fetrow, T. V.; Daly, S. R. "Mechanochemical Synthesis and Structural Analysis of Trivalent Lanthanide and Uranium Diphenylphosphinodiboranates." Dalton Trans. 2021, 50, 11472–11484 (link).

Fetrow, T. V.; Bhowmick, R.; Achazi, A. J.; Blake, A. V.; Eckstrom, F. D.; Vlaisavljevich, B.; Daly, S. R. "Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates." Inorg. Chem. 2020, 59, 48-61 (link).

Ligand K-edge XAS Studies

Ligand K-edge X-ray absorption spectroscopy (XAS) is a powerful tool for interrogating bonding and electronic structure in metal complexes. Most notably, the intensity of pre-edge transitions in a ligand K-edge XAS spectrum provides quantitative information that can be used to assess variations in metal-ligand covalency within a series of complexes. We collect ligand K-edge XAS to determine how changes to diphosphorus ligands affect metal-ligand covalency in transition metal complexes and homogeneous catalysts. Our group recently showed that this technique is sensitive enough to detect subtle variations in metal-phosphorus covalency as a function of diphosphine bite angle and coordination geometry, and we are now using this information to develop bonding models to help evaluate structure-reactivity relationships.

Recent Publications: Lee, K.; Blake, A. V.; Donahue, C. M.; Spielvogel, K. D.; Bellott, B. J.; Daly, S. R. "Quantifying the Interdependence of Metal-Ligand Covalency and Bond Distance using Ligand K-edge XAS." Angew. Chem., Int. Ed. 2019, 58, 12451-12455 (link).

Lee, K.;* Blake, A. V.;* Tanushi, A.; McCarthy, S. M.; Kim, D.; Loria, S. M.; Donahue, C. M.; Spielvogel, K. D.; Keith, J. M.; Daly, S. R.; Radosevich, A. T. " Validating the Biphilic Hypothesis of Nontrigonal P(III) Compounds." Angew. Chem., Int. Ed. 2019, 58, 6993-6998 (link). *Equal contributions.

Lee, K.; Wei, H.; Blake, A. V.; Donahue, C. M.; Keith, J. M.; Daly, S. R. "Measurement of Diphosphine σ-Donor and π-Acceptor Properties in d⁰Titanium Complexes Using Ligand K-edge XAS and TDDFT." Inorg. Chem. 2018, 57, 10277-10286.

Donahue, C. M.; Daly, S. R. "Ligand K-edge XAS Studies of Metal-Phosphorus Bonds: Applications, Limitations, and Opportunities." Comments Inorg. Chem. 2018, 38, 54-78 (link).

Research Projects

Multifunctional Ligands

Synthesis of Reactive and Multifunctional Ligands

Cooperative Ligand-Centered Reactivity

Lanthanide and Trivalent Actinide Chemistry

Ligand K-edge XAS Studies