Catalysis is at the core of sustainable chemistry. Many catalytic processes, however, rely on elements that are expensive, in short supply or have a significant environmental footprint associated with their extraction and isolation. The Chirik group is exploring “modern alchemy” for sustainable chemistry – a concept defined as using ligand design to transmute the function of an earth abundant metal to mimic or ideally surpass the performance of more exotic precious elements.
Our approach is multidisciplinary, spanning the traditional areas of organic and inorganic chemistry. At the core of our work is understanding and manipulating electron flow in first row transition metal compounds. We integrate modern spectroscopic and theoretical methods to accomplish these objectives. In one limit, oxidation and reduction chemistry occurs cooperatively between the metal and the supporting ligand. This concept of “redox active” ligands has resulted in new base metal catalysts for the asymmetric hydrogenation of alkenes as well as the hydrosilylation and hydroboration of olefins.
In each case, the base metal catalysts offer unique function over established precious metals catalysts.
Our catalyst development efforts are often paired with industrial partners as our catalysts find relevance to problems in the pharmaceutical, flavor and fragrance, petrochemical and silicones industries. In chemistry unique to these electronic structures, we have also discovered unprecedented cycloaddition reactions that overcome the constraints of orbital symmetry and enable a new, thermal route to various cyclobutane derivatives. The applications of these methods to various synthetic targets are under investigation.
An alternative approach is confining redox changes to the base metal. In this so-called strong field limit, the base metal catalysts are sufficiently electron rich to enable the activation and functionalization of ubiquitous but otherwise kinetically inert C-H bonds. A general, cobalt-catalyzed method for C-H borylation has been discovered with distinct advantages over existing precious metal catalysts. The application of this process to various synthetic challenges are currently under investigation. More broadly, our group actively explores how manipulation of electronic structure can be applied to new problems in catalysis.
A second area of long-standing interest is the fixation of molecular nitrogen, N2. While the industrial Haber-Bosch process has had a transformative impact on society – enabling food production for approximately half of the world’s population and accounting for half of the nitrogen in the body – the fossil fuel inputs and carbon footprint associated with this reaction inspire the search for alternatives. Our laboratory is developing new routes to N-H and N-C bond forming reactions using molecular nitrogen as the building block. If successful, these methods would either circumvent the Haber-Bosch process or result in ammonia synthesis methods that are compatible with renewable hydrogen. To accomplish these objectives, we study early transition metal complexes that by virtue of their designed coordination environment, activate or even cleave the strong NN bond in N2. One particularly notable process is ligand-induced N2 bond cleavage, where various ureas, oxamides, formates and amines have been synthesized from N2 and CO – diatomic molecules with the two strongest bonds in chemistry.
US EPA Presidential Green Chemistry Challenge Award (2016)
Nankai-Asymchem Lecture (2016)
Editor-in-Chief, Organometallics (2015)
First Japanese Society of Coordination Chemistry Award for Creative Work (2015)
Xingda Lecture, Peking University (2015)
Closs Lecturer, University of Chicago (2014)
Dalton Lecturer of the Royal Society of Chemistry (2011)
Defense Science Study Group (2010-2011)
Blavatnik Award, New York Academy of Sciences (2009)
Arthur C. Cope Scholar Award, American Chemical Society (2009)
Bessel Fellow of the Alexander von Humboldt Foundation (2008)
Camille Dreyfus-Teacher Scholar (2006)
Stephen and Margery Russell Distinguished Teaching Award (2005)
Cottrell Scholar, Research Corporation (2004)
David and Lucile Packard Fellow in Science and Engineering (2004)
NSF CAREER Award (2003)
Base Metal Catalysis
Atienza, C. C. H.; Diao, T.; Weller, K. J.; Nye, S. A.; Lewis, K. M.; Delis, J. G. P.; Boyer, J. L.; Roy, A. K.; Chirik, P. J. “Bis(imino)pyridine cobalt-catalyzed dehydrogenative silylation of alkenes: Scope, mechanism and orgins of selective allylsilane formation.” J. Am. Chem. Soc. 2014, 136, 12108-12118.
Semproni, S. P.; Milsmann, C.; Chirik, P. J. “Four-coordinate cobalt pincer complexes: Electronic structure studies and ligand modification by homolytic and heterolytic pathways.” J. Am. Chem. Soc. 2014, 136, 9211-9224.
Obligacion, J. V.; Semproni, S. P.; Chirik, P. J. “Cobalt catalyzed C-H borylation.” J. Am. Chem. Soc. 2014, 136, 4133-4136.
Obligacion, J. V.; Chirik, P. J. “Bis(imino)pyridine cobalt-catalyzed alkene isomerization hydroboration: A strategy for remote hydrofunctionalization with terminal selectivity.” J. Am. Chem. Soc. 2013, 135, 19107-19110.
Friedfeld, M. R.; Shevlin, M.; Hoyt, J. M.; Krska, S. W.; Tudge, M. T.; Chirik, P. J. “Cobalt precursors for high throughput discovery of base metal asymmetric hydrogenation catalysts.” Science, 2013, 342, 1076-1080.
Yu, R. P.; Darmon, J. M.; Milsmann, C.; Margulieux, G. W.; Stieber, S. C. E.; DeBeer, S.; Chirik, P. J. “Catalytic hydrogenation activity and electronic structure determination of bis(arylimidazol-2-ylidene)pyridine cobalt alkyl and hydride complexes.” J. Am. Chem. Soc. 2013, 135, 13168-13185.
Tondreau, A. M.; Atienza, C. C. H.; Weller, K. J.; Nye, S. A.; Lewis, K. M.; Delis, J. G. P.; Chirik, P. J. “Iron catalysts for selective anti-Markovnikov alkene hydrosilylation using tertiary silanes.” Science 2012, 335, 567-570.
Milsmann, C.; Semproni, S. P.; Chirik, P. J. “N-N bond cleavage of 1,2-diarylhydrazines and N-H bond formation via H-atom transfer in vanadium complexes supported by a redox-active ligand.” J. Am. Chem. Soc. 2014, 136, 12099-12107.
Semproni, S. P.; Chirik, P. J. “Activation of N2-derived hafnium nitrides for nucleophilic N-C bond formation with a terminal isocyanate.” Angew. Chem. Int. Ed. Engl. 2013, 52, 12965-12969.
Semproni, S. P.; Chirik, P. J. “Synthesis of a base-free hafnium nitride from N2 cleavage: A versatile platform for dinitrogen functionalization.” J. Am. Chem. Soc. 2013, 135, 11373-11383.
Semproni, S. P.; Knobloch, D. J.; Milsmann, C.; Chirik, P. J. “Redox-induced N2 hapticity switching in zirconocene dinitrogen complexes.” Angew. Chem. Int. Ed. 2013, 52, 5372-5376.
Semproni, S. P.; Milsmann, C.; Chirik, P. J. “Structure and reactivity of a hafnocene m-nitrido prepared from dinitrogen cleavage.” Angew. Chem. Int. Ed. 2012, 51, 5213-5216.