caa a22 4500 606173692 CHVBK 20210128100734.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s11244-015-0414-9 doi (NATIONALLICENCE)springer-10.1007/s11244-015-0414-9 EPR Spectroscopy as a Tool in Homogeneous Catalysis Research [Elektronische Daten] [Monalisa Goswami, Andrei Chirila, Christophe Rebreyend, Bas de Bruin] In the context of homogeneous catalysis, open-shell systems are often quite challenging to characterize. Nuclear magnetic resonance (NMR) spectroscopy is the most frequently applied tool to characterize organometallic compounds, but NMR spectra are usually broad, difficult to interpret and often futile for the study of paramagnetic compounds. As such, electron paramagnetic resonance (EPR) has proven itself as a useful spectroscopic technique to characterize paramagnetic complexes and reactive intermediates. EPR spectroscopy is a particularly useful tool to investigate their electronic structures, which is fundamental to understand their reactivity. This paper describes some selected examples of studies where EPR spectroscopy has been useful for the characterization of open-shell organometallic complexes. The paper concentrates in particular on systems where EPR spectroscopy has proven useful to understand catalytic reaction mechanisms involving paramagnetic organometallic catalysts. The expediency of EPR spectroscopy in the study of organometallic chemistry and homogenous catalysis is contextualized in the introductory Sect.1. Section2 of the review focusses on examples of C-C and C-N bond formation reactions, with an emphasis on catalytic reactions where ligand/substrate non-innocence plays an important role. Both carbon and nitrogen centered radicals have been shown to play an important role in these reactions. A few selected examples of catalytic alcohol oxidation proceeding via related N-centered ligand radicals are included in this section as well. Section3 covers examples of the use of EPR spectroscopy to study important commercial ethylene oligomerization and polymerization processes. In Sect.4 the use of EPR spectroscopy to understand the mechanisms of Atom Transfer Radical Polymerization is discussed. While this review focusses predominantly on the application of EPR spectroscopy in mechanistic studies of C-C and C-N bond formation reactions mediated by organometallic catalysts, a few selected examples describing the application of EPR spectroscopy in other catalytic reactions such as water splitting, photo-catalysis, photo-redox-catalysis and related reactions in which metal initiated (free) radical formation plays a role are included as well. EPR spectroscopic investigation in this area of research are dominated by EPR spectroscopic studies in isotropic solution, including spin trapping experiments. These reactions are highlighted in Sect.5. EPR spectroscopic studies have proven useful to discern the correct oxidation states of the active catalysts and also to determine the effective concentrations of the active species. EPR is definitely a spectroscopic technique that is indispensable in understanding the reactivity of paramagnetic complexes and in conjunction with other advanced techniques such as X-ray absorption spectroscopy and pulsed laser polymerization it will continue to be a very practical tool. The Author(s), 2015 EPR spectroscopy nationallicence Homogeneous catalysis nationallicence Metallo-radicals nationallicence Ligand-radicals nationallicence Substrate-radicals nationallicence Redox noninnocent nationallicence Goswami Monalisa Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut Chirila Andrei Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, Van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH, Amsterdam, The Netherlands aut Rebreyend Christophe Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut de Bruin Bas Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut Topics in Catalysis Springer US; http://www.springer-ny.com 58/12-13(2015-09-01), 719-750 1022-5528 58:12-13<719 2015 58 11244 https://doi.org/10.1007/s11244-015-0414-9 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11244-015-0414-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Goswami Monalisa Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut NATIONALLICENCE 700 1- Chirila Andrei Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, Van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH, Amsterdam, The Netherlands aut NATIONALLICENCE 700 1- Rebreyend Christophe Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut NATIONALLICENCE 700 1- de Bruin Bas Department of Homogeneous Catalysis, Van 't Hoff Institute for Molecular Sciences, Faculty of Science, Universiteit Van Amsterdam, Postbus 94720, 1090 GS, Amsterdam, The Netherlands aut NATIONALLICENCE 773 0- Topics in Catalysis Springer US; http://www.springer-ny.com 58/12-13(2015-09-01), 719-750 1022-5528 58:12-13<719 2015 58 11244