A solution and solid state study of niobium complexes University of ...

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Acknowledgements First and foremost, I thank God Almighty for the countless blessings he has given me. Thank you to Prof. Roodt for all the opportunities, patience and endless enthusiasm for chemistry, inspiring me to learn as much as I can. It is truly an honour to be known as one of your students. To Prof. Deon Visser, thank you for all your guidance and encouragement. Your neverending patience and willingness to give advice is what kept me motivated throughout my studies. To Dr. Linette Bennie, thank you for your guidance with the niobium NMR throughout this project. Thank you to all my colleagues in the Inorganic group for all the laughter and jokes. Thank you for sharing your knowledge and for your patience when having to explain something several times. Every one of you contributed to this study in some way and for that I thank you. To my father, Lucas Herbst, my sister, Shané Herbst, and my grandmother, Nellie Grobler, without your love, support, faith, sacrifices, understanding and continuous encouragement this would not be possible. Financial assistance from the Advanced Metals Initiative (AMI) of the Department of Science and Technology (DST) of South Africa, through The New Metals Development Network (NMDN) coordinated by the South African Nuclear Energy Corporation Limited (Necsa), and the University of the Free State are gratefully acknowledged.
Table of contents Abbreviations and Symbols………………………………………………………………………………… V Abstract…………………………………………………………………………………………………………….. VI Opsomming……………………………………………………………………………………………….……. VIII 1 Introduction ......................................................................................... 1 1.1 History of Niobium .............................................................................................. 1 1.2 The Aim of this Study ......................................................................................... 2 2 Literature Review of Niobium ............................................................ 4 2.1 Introduction ........................................................................................................ 4 2.1.1 Properties of Niobium .................................................................................. 5 2.1.2 Uses ............................................................................................................ 8 2.2 Separation of Niobium and Tantalum………………………………………………..10 2.2.1 Marignac Process ...................................................................................... 10 2.2.2 Solvent Extraction ...................................................................................... 10 2.2.3 Current Research ...................................................................................... 11 2.3 Purification ....................................................................................................... 12 2.4 Chemistry of Niobium ....................................................................................... 13 2.4.1 Oxides ....................................................................................................... 13 2.4.2 Halides....................................................................................................... 14 2.4.3 Borides ...................................................................................................... 15 2.4.4 Carbides .................................................................................................... 15 2.4.5 Nitrides ...................................................................................................... 15 2.4.6 Water absorption ....................................................................................... 16 2.4.7 Silicates ..................................................................................................... 16 I
Page 1: A solution and solid state study of
Page 5 and 6: 3.4 Infrared Spectroscopy (IR) ....
Page 7 and 8: Abbreviations and Symbols Abbreviat
Page 9 and 10: Abstract 93 Nb NMR was successfully
Page 11 and 12: Opsomming 93 Nb KMR is met sukses g
Page 13 and 14: Chapter 1 metals. 3 Due to Wollasto
Page 15 and 16: Synopsis... 2. Literature Review of
Page 17 and 18: Chapter 2 Niobium resembles tantalu
Page 19 and 20: 2.1.2 Uses Chapter 2 Niobium has a
Page 21 and 22: 2.2 Separation of Nb and Ta 2.2.1 M
Page 23 and 24: Chapter 2 Buachuang et al. 16 repor
Page 25 and 26: Chapter 2 Niobium oxide surfaces ex
Page 27 and 28: 2.4.6 Water absorption Chapter 2 Th
Page 29 and 30: Chapter 2 been reported in literatu
Page 31 and 32: Chapter 2 containing niobium as the
Page 33 and 34: Chapter 2 conclusions, with regard
Page 35 and 36: Chapter 2 Figure 2.5: Structure of
Page 37 and 38: 2.6.3.3 [NbCl3O(ttbd) - ] Chapter 2
Page 39 and 40: Chapter 2 (a) (b) Figure 2.10: Stru
Page 41 and 42: 2.7 Alkoxides Chapter 2 Specific kn
Page 43 and 44: Chapter 2 Reactions of dialkylamid
Page 45 and 46: Chapter 2 other NbCl5-x(OMe)x produ
Page 47 and 48: Chapter 2 In 1991 Lee et al. 83 pub
Page 49 and 50: EtO EtO EtO EtO Cl Nb Cl Cl Nb Cl R
Page 51 and 52: Chapter 2 The hemicarbonate formed
Page 53 and 54:
Synopsis... 3. Synthesis and Charac
Page 55 and 56:
Chapter 3 with γ = magnetogyric ra
Page 57 and 58:
Chapter 3 electromagnetic spectrum
Page 59 and 60:
3.5.1 Bragg’s law Chapter 3 Bragg
Page 61 and 62:
3.5.3 ‘Phase problem’ Chapter 3
Page 63 and 64:
Chapter 3 A = ∑ ε cl (3.14) In
Page 65 and 66:
Chapter 3 t1/2 = 54 = . 3.7 Sy
Page 67 and 68:
3.7.2.4 Synthesis of [NbCl4(acac)]:
Page 69 and 70:
4. Crystallographic Synopsis... Cha
Page 71 and 72:
Chapter 4 packages 2 respectively.
Page 73 and 74:
Chapter 4 4.3 Crystal Structure of
Page 75 and 76:
Chapter 4 longer bonds (C1-C2, C2-C
Page 77 and 78:
Chapter 4 Figure 4.5: Packing of [N
Page 79 and 80:
Chapter 4 Figure 4.7: Molecular str
Page 81 and 82:
Chapter 4 Table 4.5: Selected bond
Page 83 and 84:
Chapter 4 Figure 4.11: Molecular st
Page 85 and 86:
Chapter 4 Figure 4.12: The phacac p
Page 87 and 88:
Chapter 4 Table 4.9: Hydrogen bonds
Page 89 and 90:
Chapter 4 According to our knowledg
Page 91 and 92:
5.2 Experimental procedures 5.2.1 K
Page 93 and 94:
Chapter 5 corresponds to one specie
Page 95 and 96:
5.3 Results and Discussion 5.3.1 Pr
Page 97 and 98:
Chapter 5 Figure 5.5: Typical UV/Vi
Page 99 and 100:
5.3.3 Derivation of the rate law Ch
Page 101 and 102:
Chapter 5 The Stopped-flow data (fa
Page 103 and 104:
Chapter 5 Figure 5.9: Eyring plot,
Page 105 and 106:
Chapter 5 However, more information
Page 107 and 108:
Chapter 6 second reaction entailed
Page 109 and 110:
Appendix A Table 1.3: Bond angles (
Page 111 and 112:
Appendix A A 2 Supplementary Data f
Page 113 and 114:
Appendix A C(16)-H(16B) 0.96 C(16)-
Page 115 and 116:
Appendix A O(7)-C(10)-C(11) 123.6 (
Page 117 and 118:
Appendix A H(18E)-C(18B)-H(18F) 109
Page 119 and 120:
Appendix A H(18F) 6243 6605 575 75
Page 121 and 122:
Appendix A Table 3.3: Bond angles (
Page 123 and 124:
Appendix A Table 3.4: Anisotropic d
Page 125:
Appendix B Appendix B B 1 Supplemen
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