Metals exist in solution coordinated to ligands to form coordination complexes, which can act as catalysts for important chemical transformations. Among most ubiquitous classes of ligands are β-diketonates, of which the ligand acetylacetonate or "acac" is the most common. Metal acetylacetonates are widely used in a variety of important chemical applications; however, their use in catalysis is limited because they tend to form complexes that are coordinatively saturated, meaning that they don't easily permit substrates to bind. 

We have designed and synthesized a series of β-diketonate ligands that are functionalized with large m-terphenyl groups that prevent coordinative saturation at the metal. These new ligands provide a platform for detailed investigations into catalytic mechanisms that should help us discover and optimize new catalytic chemical transformations that could have an impact in the synthesis of organic chemicals. β-diketonate ligands coordinate to metals in vastly different ways than other ligands that have been investigated. In particular, they are weak σ-bond donors like water, but strong π-acceptors, like cyanide. This provides a unique electronic environment that could open the door to discovery of new reactivity and chemical transformations.

Hopkins, E. J.; Krajewski, S. M.; Crossman, A. S.; Maharaj, F. D. R.; Schwanz, L. T.; Marshak, M. P. Group 4 Organometallics Supported by Sterically Hindered β‐DiketonatesEur. J. Inorg. Chem. 2020, 20, 1951–1959.

Larson, A. T.; Crossman, A. S.; Krajewski, S. M.; Marshak, M. P. Copper(II) as a Platform for Probing the Steric Demand of Bulky β-Diketonates. Inorg. Chem. 202059, 423–432.

Krajewski, S. M.; Crossman, A. S.; Akturk, E. S.; Suhrbier, T.; Scappaticci, S. J.; Staab, M. W.; Marshak, M. P. Sterically encumbered β-diketonates and base metal catalysisDalton Trans. 201948, 10714–10722.

Crossman, A. S.; Larson, A. T.; Shi, J. X.; Krajewski, S. M.; Akturk, E. S.; Marshak, M. P. Synthesis of Sterically Hindered β-Diketones via Condensation of Acid Chlorides with EnolatesJ. Org. Chem201984 (11), 7434–7442.

Akturk, E. S.; Scappaticci, S. J.; Seals, R. N.; Marshak, M. P. Bulky β-Diketones Enabling New Lewis Acidic Ligand PlatformsInorg. Chem. 2017, 56 (19), 11466–11469.