NMR Spectroscopy of Exotic Quadrupolar Nuclei in Solids by Alexandra Faucher A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry University of Alberta © Alexandra Faucher, 2016 Abstract This thesis is concerned with NMR studies of solids containing NMR-active quadrupolar nuclei typically overlooked due to their unfavorable NMR properties, particularly moderate to large nuclear electric quadrupole moments. It is shown that 75As, 87Sr, and 121/123Sb NMR spectra of a wide range of solid materials can be obtained. Traditional 1D pulse sequences (e.g., Bloch pulse, spin echo, QCPMG) are used alongside new methods (e.g., WURST echo, WURST-QCPMG) to acquire the NMR spectra; the advantages of these new methods are illustrated. Most of these NMR spectra were acquired at an external magnetic field strength of B0 = 21.14 T. Central transition (mI = 1/2 to −1/2) linewidths of half-integer quadrupolar nuclei of up to a breadth of ca. 32 MHz are obtained at B0 = 21.14 T, demonstrating that nuclear sites with large nuclear quadrupolar coupling constants can be characterized. Many of the NMR spectra contained in this research depict situations in which the nuclear quadrupolar interaction is on the order of or exceeds the magnitude of the Zeeman interaction, thus rendering the high-field approximation invalid and requiring exact treatment in which the full Zeeman-quadrupolar Hamiltonian is diagonalized in order to properly simulate the NMR spectra and extract NMR parameters. It is also shown that both direct (Reff) and indirect (J) spin-spin coupling between quadrupolar nuclei can be quantified in some circumstances, and that the signs of the isotropic indirect spin-spin coupling and the nuclear quadrupolar coupling constants can be obtained experimentally in cases of high-field approximation breakdown. This research represents a relatively large and valuable contribution to the available 75As, 87Sr, and 121/123Sb NMR data in the literature. For example, experimentally determined chemical shift anisotropy is reported for the 87Sr nucleus in a powdered solid for the first time, and the NMR parameters for 11B-75As spin-spin coupling constants reported here add to a sparse collection of information on ii quadrupolar spin-pairs. Overall, this research is a step towards the goal of utilizing the entire NMR periodic table for the characterization of molecular and crystallographic structure as well as structural dynamics. iii Preface This thesis is an original work by Alexandra Faucher. Chapter 3 of this thesis has been reprinted with permission from Faucher, A.; Terskikh, V. V.; − Wasylishen, R. E. Assessing distortion of the AF6 (A = As, Sb) octahedra in solid hexafluorometallates(V) via NMR spectroscopy. Can. J. Chem. 2015, 93, 938-944. Chapter 4 of this thesis has been reprinted with permission from Faucher, A.; Terskikh, V. V.; Wasylishen, R. E. Feasibility of arsenic and antimony NMR spectroscopy in solids: An investigation of some group 15 compounds. Solid State Nucl. Magn. Reson. 2014, 61-62, 54-61. Copyright 2014 Elsevier. Chapter 5 of this thesis has been reprinted with permission from Faucher, A.; Terskikh, V. V.; Wasylishen, R. E. Spin-spin coupling between quadrupolar nuclei in solids: 11B-75As spin pairs in Lewis acid-base adducts. J. Phys. Chem. A. 2015, 119, 6949-6960. Copyright 2015 American Chemical Society. 75 For the above publications, I acquired all NMR data at B0 = 7.05 and 11.75 T. Some of the As 121/123 and Sb NMR experiments performed at B0 = 21.14 T were also performed by me during my visits to the National Ultrahigh-Field NMR Facility for Solids in Ottawa, ON, Canada. The majority of the NMR spectra acquired at B0 = 21.14 T were collected by Victor V. Terskikh, the manager of our ultrahigh-field NMR facility. Data analysis was made by me, with the exception of the variable temperature NMR spectra acquired at B0 = 21.14 T shown in Chapter 3 and the iv 75As NMR spectrum of arsenobetaine bromide shown in Chapter 4. I have prepared all of the above manuscripts for publication. Chapter 6 of this thesis has been reprinted with permission from Faucher, A.; Terskikh, V. V.; Ye, E.; Bernard, G. M.; Wasylishen, R. E. Solid-State 87Sr NMR Spectroscopy at Natural Abundance and High Magnetic Field Strength. J. Phys. Chem. A, 2015, 119, 11847-11861. Copyright 2015 American Chemical Society. Data were collected for this project by each listed author, analysis of the data was made by Victor V. Terskikh, Eric Ye, and myself, and I prepared the manuscript for publication. The published abstracts for these articles have been used in Chapter 1 as a summary of each project. Minor details (e.g., symbols) have been modified from their original published appearance for the sake of consistency throughout this thesis. v To my family narrow broad is beautiful 2.0 0.0 -2.0 -4.0 MHz vi Acknowledgements I would like to acknowledge Rod Wasylishen for giving me the opportunity to study solid-state NMR spectroscopy in his laboratory. Rod’s encouragement, enthusiasm, and dedication to scientific rigor were a large part of what made working in this lab so enjoyable. I thank him for his guidance and support throughout my studies at the University of Alberta. I would like to thank my supervisory committee, Alex Brown and Jonathan Veinot, for inspiring and assisting me throughout my studies. I also thank Rob Schurko and Nils Petersen for serving on my Ph.D. examination committee. I thank all of the present and former members of the Wasylishen group. Specifically, I thank Tom Nakashima and Kris Harris for their guidance during my early days in the group, and Guy Bernard for his much-appreciated assistance over the years. I owe a huge thank you to my office-mate and friend, Rosha Teymoori, for keeping me sane over the last few years. My studies here would not have been possible without the help of the support staff and facilities in our Department. I am incredibly grateful to Mark Miskolzie, Ryan McKay, and Nupur Dabral for their training, troubleshooting assistance, and helpful conversations. I would also like to thank Mark for taking the time to teach me many things about NMR spectrometer maintenance. I thank Dieter Starke and Allan Chilton for their time/assistance fixing electronics and other equipment, Robert McDonald and Stanislav Stoyko for their assistance in X-ray crystallography, and Wayne Moffat for many other analytical services. Klaus Eichele and David Bryce are thanked for the development and maintenance of NMR simulation programs WSolids and QUEST, without which this work could not have been completed. Frédéric Perras is thanked for writing QUEST and providing me with the program used to simulate the RDC NMR spectra in Chapter 5. I also thank Victor Terskikh at the vii National Ultrahigh-field NMR Facility for Solids in Ottawa, ON, Canada. Victor is thanked for acquiring and analyzing some of the spectra contained in this work, as well as for training and supervising me during my visits to the facility. I am grateful to my friends and family for their love and support. Specifically, I thank Julia, Don, and Christina Palech, Bryan Faucher, and Christine Newlands. A special thanks goes to my dad for frequently reminding me why not to eat expired dip.* Thank you for all of the wonderful nights of board games, wine, and delicious food. I love you all! * “I am sure your food poisoning was from that chip dip dated Feb 5 as I was pretty sick after eating some from that container last night!” – Don Palech, February 26, 2012 viii Table of Contents 1 Introduction 1 1.1 Background and Motivation 1 1.2 Overview of Projects 4 − 1.2.1 Assessing Distortion of the AF6 (A = As, Sb) Octahedra in Solid 4 Hexafluorometallates(V) via NMR Spectroscopy 1.2.2 Feasibility of Arsenic and Antimony NMR Spectroscopy in Solids: 5 An Investigation of Some Group 15 Compounds 1.2.3 Spin-spin Coupling Between Quadrupolar Nuclei in Solids: 11B- 6 75As Spin Pairs in Lewis Acid-Base Adducts 1.2.4 Solid-State 87Sr NMR Spectroscopy at Natural Abundance and 7 High Magnetic Field Strength 2 Theoretical Background 8 2.1 Nuclear Spin Angular Momentum 8 2.1.1 Classical Angular Momentum 8 2.1.2 Quantum (Orbital) Angular Momentum 9 2.1.3 Quantum Spin Angular Momentum 10 2.1.4 Origin of Nuclear Spin Number 11 2.1.5 Nuclear Magnetic Moments and the Gyromagnetic Ratio 12 2.2 The NMR Hamiltonian 13 2.2.1 The Zeeman Interaction 16 2.2.2 The Boltzmann Distribution and the Net Magnetization 18 ix 2.2.3 Radiofrequency Pulses 19 2.2.4 Magnetic Shielding and Chemical Shift 22 2.2.5 Direct Dipolar Coupling 25 2.2.6 Indirect Spin-Spin Coupling 27 2.2.7 Quadrupolar Interaction 27 2.2.8 Exact Calculations for Large Quadrupolar Interactions 34 2.3 Nuclear Relaxation 35 2.4 The Fourier Transform 38 2.5 Experimental NMR Techniques 40 2.5.1 Magic Angle Spinning (MAS) 40 2.5.2 Spin Echo 41 2.5.3 QCPMG 41 2.5.4 WURST 42 2.5.5 WURST-QCPMG 44 2.5.6 Acquiring Ultrawideline NMR Spectra 44 2.5.7 Assembling Ultrawideline NMR Spectra 45 2.5.8 Computational Methods 46 2.5.8.1 Amsterdam Density Functional (ADF) 46 2.5.8.2 Cambridge Serial Total Energy Package (CASTEP) 46 − 3 Assessing Distortion of the AF6 (A = As, Sb) Octahedra in Solid 48 Hexafluorometallates(V) via NMR Spectroscopy 3.1 Introduction 48 x 3.2 Background 49 3.3 Crystal Structure and Dynamics 52 3.3.1 KAsF6 52 3.3.2 KSbF6 53 3.4 Experimental Section 54 3.5 Results and Discussion 57 3.5.1 KAsF6 66 3.5.2 KSbF6 70 3.6 Conclusions 71 3.7 Acknowledgements 72 4 Feasibility of Arsenic