Organic Chemistry Seminar: Bespoke Ligand Design in Earth-Abundant Metal Catalysis: Small Changes Lead to Big Differences

Abstract:

The con(nuous effort to present a more sustainable outlook has led to a renaissance in the use of earthabundant metals in homogenous catalysis. Their natural abundance, low-toxicity, and ready availability have been strong incen(ves to replace their less environmentally friendly noble metal counterparts. In addi(on, the smaller ionic radii and typically high-spin electronic structure of earth-abundant metals have resulted in unique reac(vity. With the advent of new reac(vity in earth-abundant metal catalysis, also comes novel mechanisms. In this lecture we will review earth-abundant metal ligand design and demonstrate how the addi(on of one carbon atom can make all the difference in mechanisms that occupy different redox spaces (e.g., one- vs. two-electron chemistry),1 rely on spin-accelera(on,2 or rely on selec(ve 1,2-alkyl migra(on from metal to ligand.3 We will highlight these processes with the chemistry of iron in aryl-aryl cross-coupling, alkene metathesis, and alkene isomeriza(on (Figure 1). In the highlighted methodologies will explore how the oxida(on and spin-state of the earthabundant metal influences its reac(vity and demonstrate how these differences in reac(vity can be used in catalysis that is akin or beHer than those of their precious metal counterparts. 

References:

1. Garhwal, S.; Kaushansky, A.; Fridman, N.; Shimon, L. J. W.; and de Ruiter, G. Facile H/D Exchange at (Hetero)Aroma7c Hydrocarbons Catalyzed by a Stable Trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex. J. Am. Chem. Soc. 2020. 142, 17131.

2. Garhwal, S.; Kaushansky, A.; Fridman, A.; de Ruiter, G. Part-Per-Million (PPM) Levels of an Anionic Iron-Hydride Complex Catalyzes Selec7ve Alkene Isomeriza7on with Nobel Metal Reac7vity. Chem Catalysis, 2021, 1, 631.

3. Sakthi Raje, Subhash Garhwal, Katarzyna Młodzikowska-Pieńko, Tofayel Sheikh Mohammed, Ron Raphaeli, Natalia Fridman, Linda J. W. Shimon, Renana Gershoni-Poranne, and Graham de Ruiter*. Reversible 1,2-Methyl MigraQon to an N-Heterocyclic Carbene in a PCNHCP Cobalt(I) Complex Enables StereoselecQve (E and Z) Allyl Ether IsomerizaQon. JACS Au., 2024, 4, 4234-4248 
 

Event Organizer: Dr. Muhammad Jbara