Inorganic Chemistry Seminar: Dr. Milton Smith, MSU

December 04, 2018 - 12:00 PM - 01:00 PM
Speaker: 

Dr. Milton Smith

 

 

Catalysts that Cleave C–H and N–H Bonds for Fine Chemical Synthesis and Energy Conversion

 

Catalytic transformations of C–H bonds are now common. This wasn’t always the case. Building from the first thermal, catalytic coupling of a borane and a hydrocarbon, our research group2 developed highly active iridium catalysts that exhibit unique regioselectivities for arene substitution and remarkable chemoselectivity for C–H functionalization. For example, sp2-C–X bonds (X = Cl, Br, and I) that are commonly cleaved in reactions with late transition metal complexes are remarkably inert to the Ir catalysts. From the roadmap we created many other groups in academia and industry have made important contributions to C–H borylations. Extensions to heterocyclic substrates and development of one-pot, catalytic reactions where the C–B bonds that result are further transformed make C–H borylation particularly attractive to synthetic chemists. Our recent work has emphasized ligand and reagent design to harness relatively weak interactions (e.g., hydrogen bonding) that are sufficiently strong to achieve  

C–H borylations with high regioselectivities.1,2

More recently, our research group has initiated a program to tap the potential for using ammonia to store, distribute, and release hydrogen gas. Specifically, we have targeted the oxidation ammonia to dinitrogen gas, protons, and electrons.3,4 Combining ammonia oxidation with ammonia synthesis from dinitrogen—the most abundant component of Earth’s atmosphere—and renewable hydrogen, a groundwork for a closed, zero-carbon fuel cycle based on nitrogen gas would be established. We recently have designed the first molecular catalyst that oxidizes NH3 to N2, six “protons,” and six electrons at room temperature. This is the anodic reaction in electrocatalytic NH3 “splitting” to N2 and H2.

 


 

 

(1) Chattopadhyay, B.; Dannatt, J. E.; Andujar-De Sanctis, I. L.; Gore, K. A.; Maleczka, R. E., Jr; Singleton, D. A.; Smith, M. R., III. J. Am. Chem. Soc. 2017, 139, 7864–7871.

(2) Smith, M. R., III; Bisht, R.; Haldar, C.; Pandey, G.; Dannatt, J. E.; Ghaffari, B.; Maleczka, R. E., Jr.; Chattopadhyay, B. ACS Catal. 2018, 8, 6216–6223.

(3) Little, D. J.; Smith, M. R., III; Hamann, T. W. Energy Environ. Sci. 2015, 8, 2775–2781.

(4) Little, D. J.; Edwards, D. O.; Smith, M. R., III; Hamann, T. W. ACS Appl. Mater. Interfaces 2017, 9, 16228–16235.

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Mindiola

inquiries rvargas@sas.upenn.edu

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu