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Proquest Dissertations COORDINATION COMPLEXES OF ALKALI METAL CROWN ETHER CATION AND GROUP 13 HYDRIDE ANIONS by Lenuta Onut B.Eng. (Honours), Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, Romania, 2002 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science In the Graduate Academic Unit of Chemistry Supervisor: Gerard Sean McGrady, D. Phil., Chemistry Department Examining Board: Jack Passmore, Ph.D., Chemistry Department External Examiner: Aurora Nedelcu, Ph.D., Biology Department This thesis is accepted Dean of Graduate Studies THE UNIVERSITY OF NEW BRUNSWICK May 2007 ©Lenuta Onut, 2007 Library and Archives Bibliotheque et 1*1 Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A 0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-56471-4 Our file Notre reference ISBN: 978-0-494-56471-4 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distribute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. 1*1 Canada DEDICATION This thesis is dedicated to my family. ii ABSTRACT This thesis describes the preparation and structural characterization of complexes formed between alkali metal-crown ether cations and Group 13 hydride anions. Crown ethers coordinated alkali metal cations have proven utility in stabilizing a range of metal hydride anions, producing high quality crystalline products. In our study, we have + explored the coordination chemistry of [M(crown)] (M = Li, Na and K) with EH4 (E = B, Al and Ga). The complexes have been characterized by single crystal X-ray diffraction and NMR spectroscopy. Cation-anion interactions occur through hydride bridges of the form M—H-E. The hapticity of the anion depends on the size of the Group 13 element and on the size and acidity of the alkali metal cation. Replacing 15-crown-5 and 18-crown-6 with their azacrown analogues and comparing the structures adopted by the BH4 complexes reveals that the azacrown systems display pronounced proton-hydrogen H-bonding of the form N-H—H—B, which leads to a chain- type arrangement of adjacent cation-anion pairs and results in these systems adopting a different space group from that of their simple crown ether counterparts. 111 ACKNOWLEDGEMENTS I would like to express my special thanks and deep appreciation to my supervisor Dr. Sean McGrady for his guidance and knowledge, and for being a constant source of ideas. This thesis has been possible only due to his constant support and encouragement. I would also like to thank him for the nice atmosphere and great moments (barbeque and curry nights). I would also like to thank Chris Willson, president of HSM Systems, for financial support and also for all the wonderful conversations that we have had. I am grateful to past (Mathi Kandiah - Sri Lanka; Aled Jones - England; Prof. Balaji Jagirdar - India; Reyna Ayabe - Hawaii; Ven Reddy - India) and present (Peter Sirsch - Germany; Richard Burchell - Wales; Henrietta Langmi - Cameroon; Terry Humphries - England; Uncharat Setthanan - Thailand; Ben Tardiff -Canada; Ranga Santhanan - India) members of the McGrady Group for teaching me experimental techniques and chemical principles and for sharing pleasant moments inside and outside the lab. Special thanks go to Dr. Peter Sirsch and Richard Burchell for their theoretical calculations. I extend my gratitude to all the faculty members, especially to Dr. Jeff Banks - Supportive Advisor; Dr. Andreas Decken - X-ray Crystallography; and Dr. Larry Calhoun - NMR Spectroscopy. My sincere thanks also go to the following staff members: Brian Malcolm - Glassblower; Dave Green - Technical Officer; Adam Fowler - Electronics Technician; Ed Goodfellow - Stores Manager; Gilles Vautour - Computer Officer; and Crystal Cavanaugh and Krista Coy - Departmental Secretaries. Thanks are due also to the members of my Reading Committee: Dr. Thomas Whidden, Dr. Ghislain Deslongchamps and Dr. John Neville; as well as the Examining Committee: Dr. Jack Passmore and Dr. Aurora Nedelcu. Furthermore, I would like to thank to all the instructors for whom I have been a Teaching Assistant: Dr. Valerie J. Reeves, Dr. Alyson Goodfellow, Dr. Peter Penner, Dr. Andreas Decken and Dr. Noureddin E. Kassimi. Finally, I would like to take the opportunity to express my infinite gratitude to my family: my husband - Vio, my mother - Anica and my brother - Daniel for their constant love, caring and encouragements throughout my studies. IV TABLE OF CONTENTS DEDICATION II ABSTRACT III ACKNOWLEDGEMENTS IV TABLE OF CONTENTS V LIST OF TABLES VIII LIST OF FIGURES X LIST OF SCHEMES XIV LIST OF SYMBOLS, NOMENCLATURE OR ABBREVIATIONS XV CHAPTER 1 INTRODUCTION 1 1.1 Hydride Complexes of Boron and Aluminum 1 1.2 Boron Hydrides as Ligands 4 1.2.1 Tetrahydroborate Ion, BH4~ 4 1.2.2 The octahydrotriborate ion, B3H8 12 1.3 Aluminum Hydrides as Ligands 14 1.4 Crown Ethers 23 1.4.1 Alkali Metal-Crown Ether Complexes 24 1.4.2 Alkali Metal Crown ether Complexes with Transition Metal Hydrides 28 CHAPTER 2 RESULTS AND DISCUSSION 31 2.1 General Aims of the Project 31 2.2 Specific Aims of this Research 32 2.3 Synthetic Routes to [M(crown)][EH4] Complexes 32 2.4 Synthesis and Characterization of [M(crown)][EH4] Complexes 35 2.4.1 [Li2(12-crown-4)3][AlH4]2 35 V 2.4.2 [Li2(12-crown-4)3][GaH4]2 36 2.4.3 [Na(15-crown-5)][BH4] 37 2.4.4 [Na(15-crown-5)][AlH4] 38 2.4.5 [K(18-crown-6)][BH4] 39 2.4.6 [K(THF)(18-crown-6)][AlH4] 40 2.4.7 [K(THF)(18-crown-6)][GaH4] 41 2.5 Analysis of the Structures Obtained by X-Ray Diffraction 42 2.5.1 [M(crown)][BH4] Structures 42 2.5.2 [M(crown)][AlH4] Structures 45 2.5.3 [M(crown)][GaH4] Structures 48 2.5.4 [Na(15-crown-5)][EH4] Structures 49 2.5.5 [K(18-crown-6)][EH4] Complexes 52 2.6 [M(azacrown)][BH4] Complexes 57 2.7 Supramolecular Structures 61 2.7.1 [Na(15-crown-5)][BH4] vs. [Na(15-azacrown-5)][BH4] 62 2.7.2 [K(18-crown-6)][BH4] vs. [K(18-azacrown-6)][BH4]/ [K(THF)(18-azacrown-6)][BH4] 66 2.8 Charge Density Analysis of [Na(15-crown-5)][EH4] Complexes 71 2.8.1 DFT Geometry Optimization 73 2.8.2 Electron Density Map 74 2.8.3 Gradient Vector Field 75 2.8.4 AIM Atomic Charges 77 2.8.5 The Laplacian of the Electron Density 78 2.8.6 Topological Parameters 79 CHAPTER 3 EXPERIMENTAL DETAILS 82 3.1 General 82 3.1.1 Solvents 83 3.1.2 General Reagents 84 vi 3.2 Instrumentation 84 3.2.1 NMR Spectroscopy 84 3.2.2 Single Crystal X-Ray Diffraction 85 3.2.3 Theoretical Calculations 85 3.3 Synthesis and Characterization 86 3.3.1 [Li2(12-crown-4)3][AlH4]2 86 3.3.2 [Li2(12-crown-4)3][GaH4]2 86 3.3.3 [Na(15-crown-5)][BH4] 87 3.3.4 [Na(15-crown-5)][AlH4] 87 3.3.5 K(18-crown-6)][BH4] 88 3.3.6 [K(THF)(18-crown-6)][AlH4] 89 3.3.7 [K(THF)(18-crown-6)][GaH4] 89 3.3.8 [Na(15-azacrown-5)][BH4] 90 3.3.9 [K(18-azacrown-6)][BH4] 90 3.3.10 [K(THF)(18-azacrown-6)][BH4] 91 3.4 Crystallographic Data 92 CHAPTER 4 OVERVIEW AND CONCLUSIONS 96 BIBLIOGRAPHY 99 VITAE 104 Vll List of Tables Table 1.1: Ionic radii of alkali metal cations and corresponding cavity sizes of crown ethers (A), log K and AH(kJ/mol) 25 Table 2.1: Complexes of alkali metal-crown ether complexes and Group 13 hydride anions obtained in crystalline form 34 Table 2.2: B-H-M distances (A) with estimated standard deviations for [M(crown)][BH4] complexes (M = NaandK) , 43 Table 2.3: M-B—H, angles (°), the distance of the metal cation from the crown plane (A) and the B—M distances (A) with estimated standard deviations for [M (crown)] [BH4] complexes 44 Table 2.4: B-H distances (A) with estimated standard deviations for [M(crown)][BH4] complexes 44 Table 2.5: Al-H—M distances (A) with estimated standard deviations for [M(crown)][AlH4] complexes (M = NaandK) 46 Table 2.6: M—Al-H, angles (°), the distance of the metal cation from the crown plane (A) and A1--M distances with estimated standard deviations for [M(crown)][AlH4] complexes 47 Table 2.7: Al-H distances (A) with estimated standard deviations for [M(crown)][AlH4] complexes 47 Table 2.8: Ga—M distances and
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