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

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Chapter 2 Table 2.2: Stereochemistries and oxidation states of niobium. 2,4 Oxidation state Coordination number Geometry Complex Nb -3 (d 8 ) 5 Trigonal bipyramidal [Nb(CO)5] 3- Nb -1 (d 6 ) 6 Octahedral [Nb(CO)6] - Nb 0 (d 5 ) 6 π Complex Nb(η 6 -mes)2 Nb +1 (d 4 ) 7 π Complex (C5H5)Nb(CO)4 Nb +2 (d 3 ) Nb +3 (d 2 ) Nb +4 (d 1 ) Nb +5 (d 0 ) 4 Square planar NbO 6 Trigonal prismatic NbS 6 Octahedral NbCl2(py)4 6 Trigonal prismatic LiNbO2 6 Octahedral Nb2Cl6(SMe2)3 8 Dodecahedral K5[Nb(CN)8] 6 Octahedral [Nb(Cl)6] 2- 7 Distorted pentagonal bipyramidal K3NbF7 7 Capped octahedron NbCl4(PMe3)3 8 Square antiprismatic Nb(β-dike)4 8 Dodecahedral K4Nb(CN)8·2H2O 8 π Complex Cp2NbMe2 4 Tetrahedral ScNbO4 5 Trigonal bipyramidal NbCl5 (g) 5 Distorted tetragonal pyramid Nb(NMe2)5 5 Square pyramidal [Nb(NMe2)5] 6 Octahedral NbOCl3 6 Trigonal prismatic [Nb(S2C6H4)3] - 7 Distorted pentagonal bipyramidal NbO(S2CNEt2)3 7 Capped Trigonal prismatic [NbF7] 2- 8 Bicapped trigonal prismatic [Nb(trop)4] + 8 Dodecahedral [Nb(O2)4] 3- 8 Square antiprismatic [NbF8] 3- 7
2.1.2 Uses Chapter 2 Niobium has a variety of useful properties; not only for the chemical industry, but also for the steel-, nuclear energy- and electronics industries. In most of the applications where tantalum or niobium can be used, tantalum is at present preferred because of its lower cost and due to the fact that it is slightly more resistant to chemical corrosion than niobium. Table 2.3: Uses of niobium. 5 Niobium Product Niobium oxide Application Benefits - Camera lenses. - Coating on glass for computer screens. - Ceramic capacitors. - Manufacture of lithium niobate for surface acoustic wave filters. Niobium carbide Cutting tool compositions. Niobium powder Niobium metal Ferro-niobium Niobiumtitanium and niobium-tin alloys Niobium capacitors for electronic circuits. Chemical processing equipment. Niobium additive to high strength low alloy steel and stainless steel. Superconducting magnetic coils in magnetic resonance imagery (MRI). 8 - High index of refraction. - High dielectric constant. - Increase light transmittance. High temperature deformation and controls grain growth. High dielectric constant, stability of oxide dielectric. Corrosion resistance. Weight reduction and increased strength and toughness due to grain refining. Very low electrical resistance of alloy wire at low temperatures. Niobium has good high temperature strength and when alloyed with other metals it has improved strength at high temperatures. Ferro-niobium is a mixture of iron and niobium and is used as an additive to improve the strength and corrosion resistance of steel. High purity ferroniobium is used in superalloys for applications as heat- resisting and combustion equipment such as jet engine and missile components. 6 5 D. L. Kepert, The Early Transition Metals, Academic Press, London, 142, 1972. 6 D. J. Soisson, J. J. McLafferty, J. A. Pierret, Ind. Eng. Chem., 53, 11, 861, 1961.
Page 1 and 2: A solution and solid state study of
Page 3 and 4: Table of contents Abbreviations and
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: Chapter 2 Niobium resembles tantalu
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)]:
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4. Crystallographic Synopsis... Cha
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Chapter 4 packages 2 respectively.
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Chapter 4 4.3 Crystal Structure of
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Chapter 4 longer bonds (C1-C2, C2-C
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Chapter 4 Figure 4.5: Packing of [N
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Chapter 4 Figure 4.7: Molecular str
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Chapter 4 Table 4.5: Selected bond
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Chapter 4 Figure 4.11: Molecular st
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Chapter 4 Figure 4.12: The phacac p
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Chapter 4 Table 4.9: Hydrogen bonds
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Chapter 4 According to our knowledg
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5.2 Experimental procedures 5.2.1 K
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Chapter 5 corresponds to one specie
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5.3 Results and Discussion 5.3.1 Pr
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Chapter 5 Figure 5.5: Typical UV/Vi
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5.3.3 Derivation of the rate law Ch
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Chapter 5 The Stopped-flow data (fa
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Chapter 5 Figure 5.9: Eyring plot,
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Chapter 5 However, more information
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Chapter 6 second reaction entailed
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Appendix A Table 1.3: Bond angles (
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Appendix A A 2 Supplementary Data f
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Appendix A C(16)-H(16B) 0.96 C(16)-
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Appendix A O(7)-C(10)-C(11) 123.6 (
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Appendix A H(18E)-C(18B)-H(18F) 109
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Appendix A H(18F) 6243 6605 575 75
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Appendix A Table 3.3: Bond angles (
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Appendix A Table 3.4: Anisotropic d
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Appendix B Appendix B B 1 Supplemen
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