22. März 2023

GDCh Kolloquium Professor Patrick Holland 22.03.2023 Professor Patrick Holland gave a talk on "Breaking it and fixing it: new chemistry with nitrogen"

Breaking it and fixing it: new chemistry with nitrogen

GDCh Kolloquium Professor Patrick Holland 22.03.2023
GDCh Kolloquium Professor Patrick Holland 22.03.2023 © Susanne Lonski (Professor Holland)
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Seminar Abstract

Atmospheric N2 is a cheap, abundant resource with great potential for energy storage and chemical synthesis, but it is difficult to convert it into other compounds ("fixing" nitrogen). This seminar will describe the challenges and opportunities of nitrogen fixation, as well as my students' discoveries of how to break the N–N bond of N2 using homogeneous transition-metal complexes. In addition to new catalysts for producing ammonia, we have identified a new mechanism for sequential C-H activation and N-N activation to create C-N bonds. Detailed mechanistic studies reveal a cyclic reaction, which gives a route from  atmospheric N2 and petroleumderived arenes to substituted anilines. This is an important step toward preparing useful chemicals using air as a starting material.

Patrick Holland was trained at Princeton University (A.B. 1993), University of California at Berkeley (Ph.D. 1997 with Robert Bergman and Richard Andersen), and University of Minnesota (postdoc 1997-2000 with William Tolman). His independent research at the University of Rochester initially focused on the properties and reactions of three-coordinate complexes of iron and cobalt. Since then, his research group has broadened its studies to iron-N2 chemistry, reactive metal-ligand multiple bonds, iron-sulfur clusters, engineered metalloproteins, redox-active ligands, solar H2 production, and the mechanisms of organometallic transformations at base metal complexes. In 2013, Prof. Holland moved to Yale University, where he is now Whitehead Professor of Chemistry. His research has been recognized with a number of awards, and election as a Fellow of the American Association for the Advancement of Science. In N2 reduction, his group has established molecular principles through which iron species are able to weaken and break the N-N bond, and has been a leader in iron chemistry relevant to the iron-molybdenum cofactor of nitrogenase.

The Holland group studies compounds containing inexpensive metals like iron and cobalt, with the goal of understanding their reactions in detail and increasing their potential for use in catalysis. We do this by preparing new molecules that are highly reactive. In some cases, the compounds have weak metal-ligand multiple bonds, and in others there are open sites for reactions on the metal. We specialize in compounds where the metal has very few bonds, and have done many detailed studies on this rare and exciting type of compound.

A major part of our research program has focused on iron complexes for nitrogen fixation. This is relevant to the industrial Haber-Bosch process for fertilizer production, and to nitrogenase, the natural enzyme that converts atmospheric nitrogen into ammonia. Other research in our laboratory has addressed solar production of hydrogen, catalytic alkene and fluorocarbon reduction, redox-active ligands, engineered metalloproteins, and fundamental organometallic mechanisms. More detail on our research is available at the Holland Group Web site.

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