Understanding Electronic Structures and Coordination Environments in Molecular and Heterogenous Catalysts from NMR

Abstract: Chemical shift has been successfully used since the beginning of NMR to identify the signature of molecules (and materials) making NMR an invaluable tool of characterizations. Because of its power to elucidate molecular structure, NMR interpretation is taught at early stage, often in laboratory courses, even before one understand the fundamentals of spectroscopy and their selection rules. We all remember solving organic and inorganic puzzles based on 1D and 2D NMR spectra during our undergraduate (and graduate…) times.(1)

This lecture, targeted for all aficionados of NMR (and those who want to become one), will concentrate on developing a detailed understanding of the origin of NMR chemical shift, and how it can be used to reconstruct the electronic structure of molecules, in particular organometallic intermediates in homogeneous and heterogenous catalysts. This lecture will also aim to show that the angular momentum operator has an “ideal” symmetry, that makes NMR a privilege spectroscopic descriptor of electronic structure and reactivity.(2) This lecture will also how chemical tensor combined with efg tensor in the case of quadrupolar nuclei can provide unique opportunity to resolve the structure of surface sites.

Bio: Christophe Copéret (CCH) was trained in chemistry and chemical engineering (CPE-Lyon) and carried out a PhD at Purdue University (E.i. Negishi). After a postdoctoral stay at Scripps (K.B. Sharpless), CCH entered CNRS and was promoted Director (1998-2008). CCH is Professor at ETH Zürich (2010) and an Associate Editor for JACS (2022). CCH is an elected member of the Academia Europaea, the French Académie des Sciences, and Swiss Academy of Engineering Sciences (SAWT). His scientific interest lies at the frontiers of molecular, material and surface chemistry with the aim to understand the electronic structure and design molecularly-defined heterogenous catalysts.

1) Spectral identification of organic compounds, Eds. Silverstein, Webster and Kiemle, Wiley&Sons, 2005.
2) a) Metal Olefin Complexes: Revisiting the Dewar-Chatt-Duncanson Model and Deriving Reactivity Patterns from Carbon-13 NMR Chemical Shift. C. P. Gordon, R. A. Andersen, C. Copéret Helvetica Chim Acta 2019, 102, e1900151. b) Carbon-13 NMR Chemical Shift: A Descriptor for Electronic Structure and Reactivity of Organometallic Compounds C.P. Gordon, C. Raynaud, R.A. Andersen, C. Copéret, O. Eisenstein, Acc. Chem. Res. 2019, 52, 2278-2289. c) Nuclear Magnetic Resonance: A Spectroscopic Probe to Understand the Electronic Structure and Reactivity of Molecules and Materials. C. P. Gordon, L. Lätsch, C. Copéret J. Phys. Chem. Lett. 2021, 12, 2072-2085. d) Classifying and understanding the reactivities of Mo-based alkyne metathesis catalysts from 95Mo NMR chemical shift descriptors. Z. Berkson, L. Lätsch, J. Hillenbrand, A. Fürstner, C. Copéret, J. Am. Chem. Soc. 2022, 144, 15020–15025. e) Well-Defined Ti Surface Sites in Ziegler-Natta Pre-Catalysts from 47/49Ti Solid-State Nuclear Magnetic Resonance Spectroscopy A. Yakimov, C. Kaul, Y. Kakiuchi, S. Sabisch, F. Morais Bolner, J. Raynaud, V. Monteil, P. Berruyer, C. Copéret J. Phys. Chem. Lett. 2024, 15, 3178–3184. DOI: 10.1021/acs.jpclett.3c03119.