High-Spin Nitrenes: A Matrix Isolation Study Dissertation To obtain the degree of Doctor of natural science (Dr. rer. nat.) by Joel Mieres Pérez from Havana Bochum 2017 Dedicated to my family. This work was carried out from February 2013 to January 2017 at the department of Organic Chemistry II of the Ruhr-Universität Bochum under the supervision of Prof. Dr. Wolfram Sander. I would like to thank Prof. Sander, not only for the great opportunity to carry out my PhD. studies in his group, but also for all the things I have learnt while discussing about chemistry with him (despite all his responsibilities, he always found the time to discuss about science when you knock on his office door). His way to approach science will always serve as inspiration for me. First Referee: Prof. Dr. W. Sander Second Referee: Prof. Dr. Patrick Nürnberger Publications J. Mieres-Pérez, E. Mendez-Vega, K. Velappan, W. Sander, Reaction of Triplet Phenylnitrene with Molecular Oxygen, J. Org. Chem. 80, 2015, 11926-11931. J. Mieres-Pérez, S. Henkel, E. Mendez-Vega, T. Schleif, T. Lohmiller, A. Sawitsky, W. Sander, J. Phys Org. Chem, 34, 2016. P. Costa, J. Mieres-Pérez, N. Oezkan, W. Sander, Activation of the B-F Bond by Diphenylcarbene: A Reversible 1,2-Fluorine Migration between Boron and Carbon Angew. Chem. Int. Ed. 56, 2017, 1760-1764 T. Schleif, J. Mieres-Pérez, S. Henkel, M. Ertelt, W. T. Borden, and W. Sander, Investigations into the Kinetics of the Cope Rearrangement of 1,5-dimethylsemibullvalene- 2(4)-d1: Experimental Evidence for Contribution of Heavy-Atom Tunneling Angew. Chem. Int. Ed. 2017, accepted. S. Radhakrishnan, J. Mieres-Pérez, M. S. Gudipati, and W. Sander, Photo-Induced Reversible Electron Transfer Between the Benzhydryl Radical and Benzhydryl Cation in Amorphous Water-Ice, Journal of Physical Chemistry A, 2017, submitted. P. Costa, I. Trosien, J. Mieres-Pérez and W. Sander, The antiaromatic tetrachlorocyclopentaylidene-BF3 Lewis complex, Journal of the American Chemical Society, 2017, submitted. J. Mieres-Pérez, P. Costa, E. Méndez-Vega, R. Crespo-Otero, W. Sander, Boron trifluoride Switches the Spin State of Pentafluorophenylnitrene. Stabilization of a Singlet Complex of an Arylnitrene, in preparation. J. Mieres-Pérez, E. Méndez-Vega, T. Schleif, W. Sander, Direct Spectroscopic Observation of three New Benzazirines and its Ring Expansion by Heavy Atom Tunneling, in preparation. S. Henkel, I. Trosien, J. Mieres-Pérez, G. Richter, N. Tötsch, T. Lohmiller, A. Savitsky, E. Sanchez-Garcia, and W. Sander, Halogen Bonding with Reactive Carbenes, in prepation. Acknowledgments First of all, I would like to thank my family, to the one in Cuba: My mother, my father, my sister, Aida, Juan, Beatriz, Juan Carlos, Javier, Carlos Joan, Suri, Pepe, Katia, Digna, Luis, Luisito, Lian and Juan Carlos Pérez; and to the new one in Spain: Maritza, Mariana, Emilio, Rebeca, Maria, Lucia, Judith, Camila, Marta, Duran, Eduardo, Lourdes, Orlando, Barbara, Claudia, Luis, Raquel, Alberto and Alejandro. Furthermore, and for these 4 years together I would like to thank all my colleagues (friends) from the lab. To the present members namely Enrique, Paolo, Tim, Corina, Pritam, Soumya, Yetsedaw, Iris, Adam, Linda, Mika, Nesli, Mohamed, and I will put Stefan as present member since there is no day in the lab that I don't use something that he teach me or an advice on how to do the things better in the lab. To all the former member, from which I keep really good memories: André, Saonli, Fee, Sandra, Melanie, Andreas, Nadja, Arun, Geneviève and Bishnu. On top of that, special thanks in this thesis to Corina and Tim for instant proofreading. There are moments (NOT a few) when you need that not only the research but also other many things related with your Ph.D. run smoothly. For all those things I would like to thanks Frau Talbot. Since I started at the RUB she always took care of the Cuban guys. I once heard from a person I admire that when one of our technicians was on holidays, the scientific production of our lab exponentially decayed over time. So this thanks goes to some of the best technicians I have the pleasure to work with: To Heidi, Torsten, Klaus, Katarina and Robin. Thanks to our secretaries: Frau Weiss, Jacinta, Hannah and Pamela for always take care of me when I was lost in the paperwork from the university. Now to the Piquete: Enrique, Kenny, Dario, Miguel, Andy, Danae, Sandra and Deamelys putting here all the things to thank for would be just too ambitious (e imprimir no es tan barato que digamos…) I will only say that these names could easily go on the first paragraph of these acknowledgments. To Prof. Dr. Elsa Sanchez-Garcia for all the things I have learned from her about science and for All The Help during the PhD. I would like to thanks two persons from which I have learned a lot during my studies in Cuba; Rachel and Reinier. Both so smart and hardworking people that I feel proud to had them once as teachers and now as friends. Finally to the person who has carried on with me every day since 4 years now, that has been patience with all the hours at the lab without arguing about it (or not much that is the same). To the person who has given me so much love and care, and with whom I expect to share the rest of my life, to my wife: Tania, this thesis is also for you. Contents Summary ................................................................................................................................... 7 General .................................................................................................................................... 13 Nitrenes ................................................................................................................................ 13 Photolysis and thermal decomposition of phenylazide ........................................................ 17 Phenylnitrene ........................................................................................................................ 20 Cyclization to benzazirines and ketenimines ....................................................................... 22 Theoretical methods for studying nitrenes ........................................................................... 25 Chapter 1. Phenyl Nitrene Reaction with Oxygen .................................................................. 30 Introduction .......................................................................................................................... 30 Results and Discussion ......................................................................................................... 33 Phenylnitrene generation in high yield ................................................................................ 33 Reaction with oxygen ........................................................................................................... 38 Chapter 2. Heavy-Atom Tunneling in the Rearrangement of Benzazirines to Ketenimines .. 51 Introduction .......................................................................................................................... 51 Results and Discussion ......................................................................................................... 54 3-allyloxy benzazirine .......................................................................................................... 54 3-methoxy benzazirine ......................................................................................................... 64 3,5-difluoro benzazirine ....................................................................................................... 70 Chapter 3. Dinitreno Pentaradicals: Organic Sextet Molecules ............................................. 76 Introduction .......................................................................................................................... 76 Results and Discussion ......................................................................................................... 78 IR spectroscopy. ................................................................................................................... 78 UV-vis spectroscopy ............................................................................................................ 80 EPR spectroscopy ................................................................................................................. 81 Chapter 4. Perfluorinated Phenylnitrene Reaction with BF3 .................................................. 91 Introduction .......................................................................................................................... 91 Results and Discussion ......................................................................................................... 93 IR spectroscopy .................................................................................................................... 93 UV-vis spectroscopy. ......................................................................................................... 108 Chapter 5. B-F bond Activation by Diphenylcarbene .......................................................... 112 Introduction ........................................................................................................................ 112 Results and Discussion ....................................................................................................... 114 IR spectroscopy .................................................................................................................