Cationic Complexes of the Group 13-15 Elements Supported by N-, P-, and O-based Ligands by Paul A. Gray B.ScH, Acadia University, 2012 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of Chemistry Paul A. Gray, 2018 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopy or other means, without the permission of the author. ii Supervisory Committee Cationic Complexes of the Group 13-15 Elements Supported by N-, P-, and O-based Ligands by Paul A. Gray B.ScH, Acadia University, 2012 Dr. Neil Burford, (Department of Chemistry) Supervisor Dr. Robin G. Hicks, (Department of Chemistry) Departmental Member Dr. David J. Berg, (Department of Chemistry) Departmental Member Dr. Jay T. Cullen, (Department of Earth and Ocean Sciences) Outside Member iii Abstract Supervisory Committee Dr. Neil Burford, (Department of Chemistry) Supervisor Dr. Robin G. Hicks, (Department of Chemistry) Departmental Member Dr. David J. Berg, (Department of Chemistry) Departmental Member Dr. Jay T. Cullen, (Department of Earth and Ocean Sciences) Outside Member This dissertation presents the synthesis and characterization of a variety of neutral and cationic complexes featuring Group 13-15 element centres stabilized by N-, P-, and O- based donors. Unique aluminum and gallium cationic complexes are obtained from equimolar reactions of the metal halide with the chelating alkyl phosphine dmpe. However, using the analogous amine donor tmeda, neutral adducts are preferred for aluminum as well as for GaCl3, while cations are obtained for GaBr3 and GaI3. New cations of Ge(II) and Sn(II) were also discovered, featuring the coordination of either bipyridine ligands or dmpe. Utilizing bipyridine led to the expected mono and dicationic chelate complexes, however, using dmpe led to the formation of unprecedented tetracationic molecules. The reactivities of the bipyridine complexes were investigated with a variety of substrates which showcased their Lewis acidity as well as their ability to be oxidized. Finally, a new series of high oxidation-state main group cations have been synthesized using a variety of ligands. The ligand choice was found to be an important role iv in compound isolation as ligand degradation occurred for some of the compounds due to their high electrophilicity. Additionally, the Lewis acidity of some of the complexes leads to interesting reaction chemistry including sp3 C-H activation. Overall, the results presented herein represent new coordination chemistry for the main group elements and opens the door towards new reactivity pathways including small molecule activation and catalysis. v Table of Contents Supervisory Committee ........................................................................................................ ii Abstract ................................................................................................................................ iii Table of Contents .................................................................................................................. v List of Tables ..................................................................................................................... xiii List of Figures .................................................................................................................... viii List of Schemes .................................................................................................................... xi Chapter 1 - Introduction ........................................................................................................ 1 1.1 Renaissance of Main Group Chemistry .................................................................... 1 1.2 Approaches to Stabilizing Reactive Main Group Centres ........................................ 2 1.2.1 Effects of Sterically Demanding Substituents .................................................. 3 1.2.2 Coordinative Stabilization from Strong Donor Molecules ............................... 7 1.3 Reactivity of Unsaturated Heavy C=C and C≡C Analogues .................................. 10 1.4 Lewis Acid-Base Chemistry ................................................................................... 15 1.4.1 Traditional Lewis Acid-Base .......................................................................... 15 1.5 Frustrated Lewis Pairs............................................................................................. 16 1.6 Bonding Considerations in Donor-Acceptor Main Group Complexes ................... 19 1.7 Synthetic Methodologies ........................................................................................ 21 1.8 Scope of Thesis ....................................................................................................... 23 Chapter 2 - Amine and Phosphine Complexes of Aluminum and Gallium Halides .......... 25 2.1 Introduction ............................................................................................................. 25 2.2 Cationic Phosphine Complexes of Aluminum ........................................................ 27 2.3 Cationic Phosphine Complexes of Gallium ............................................................ 33 2.4 Structural Alternatives to Cationic Molecules ........................................................ 41 2.5 Amine Complexes of Aluminum and Gallium Halides .......................................... 44 2.6 Summary ................................................................................................................. 49 Chapter 3 - Donor-Acceptor Complexes of Ge(II) and Sn(II) Cations .............................. 51 3.1 - Cationic 2,2’-Bipyridine Complexes of Ge(II) and Sn(II) ................................... 53 3.2 Cationic Phosphine complexes of Ge(II) and Sn(II) ............................................... 63 3.3 Summary ................................................................................................................. 72 Chapter 4 - Reactivity of Cationic Ge(II) and Sn(II) Bipyridine Complexes ..................... 74 4.1 Assessing the Lone Pair Reactivity in Ge and Sn Dications ...................................... 78 4.2 Lewis Acid Behaviour of Ge(II) and Sn(II) Dications ........................................... 84 4.3 Reaction of a Ge(II) Dication with Water............................................................... 87 4.4 Attempted Oxidation of Ge(II) and Sn(II) Dications .............................................. 90 4.5 Summary ................................................................................................................. 93 Chapter 5 - Complexes of High Oxidation-State Main Group Cations .............................. 95 5.1 Preparation of an Octahedral Gallium Tricationic Complex .................................. 99 vi 5.2 Targeting Tricationic Aluminum Complexes ....................................................... 102 5.3 Synthesis of Highly-Charged Group 14 E(IV) Complexes .................................. 107 5.4 Attempted Synthesis of P(V) Pentacationic Complexes ....................................... 115 5.5 Summary ............................................................................................................... 119 Chapter 6 – Summary ....................................................................................................... 122 Chapter 7 – Future Work .................................................................................................. 126 7.1 New Ligands in Transition Metal Catalysis .......................................................... 126 7.2 C-F Bond Activation by Main Group Cations ...................................................... 127 Chapter 8 – Experimental ................................................................................................. 129 8.1 General Procedures ............................................................................................... 129 8.2 Compounds in Chapter 2 ...................................................................................... 131 8.2.1 Synthesis of [(dmpe)2AlCl2][AlCl4] ............................................................. 131 8.2.2 Synthesis of [(dmpe)2AlBr2][AlBr4] ............................................................. 132 8.2.3 Synthesis of [(dmpe)2AlI2][AlI4] .................................................................. 132 8.2.4 Synthesis of [(dmpe)2GaCl2][GaCl4] ............................................................ 133 8.2.5 Synthesis of [(dmpe)2GaBr2][GaBr4] ............................................................ 134 8.2.6 Synthesis of [(dmpe)2GaI2][GaI4] ................................................................. 134 8.2.7 Synthesis of (tmeda)AlCl3 ............................................................................ 135 8.2.8 Synthesis of (tmeda)AlBr3 ............................................................................ 135 8.2.9 Synthesis of (tmeda)AlI3 ............................................................................... 136 8.2.10 Synthesis of (tmeda)GaCl3 ........................................................................ 136 8.2.11 Synthesis of [(tmeda)GaBr2][GaBr4] ........................................................ 137 8.2.12 Synthesis of [(tmeda)GaI2][GaI4] ............................................................. 137 8.3 Compounds in Chapter 3 .....................................................................................