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

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Opsomming Hierdie navorsingsprojek fokus op die ondersoek en identifikasie van verskeie niobium(V)komplekse wat uitgesoekte O,O’-bidentateligande bevat wat moontlik gebruik kan word vir die selektiewe skeiding van niobium en tantalum. Klem is gelê op asetielasetoon (acacH) tipe ligande as gevolg van die maklike manier waarop hulle elektroniese en steriese eienskappe verander kan word. Die kristallografiese karakterisering van drie nuwe komplekse, (asetielasetonato-κ 2 - O,O’)chloridotrimetoksidoniobium(V) (1), die “hok”-agtige struktuur tetrakis- (asetielasetonato-κ 2 -O,O’)oktakis(etoksi)tetrakis(µ 2 -okso)tetraniobium(V) (2) en die twee strukture wat verkry is vanuit dieselfde kristal, (1-feniel-1,3-butaandionato-κ 2 - O,O’)chloridotrimetoksidoniobium(V) (3a) en (1-feniel-1,3-butaandionato-κ 2 -O,O’)di- chloridodimetoksidoniobium(V) (3b), word bespreek en vergelyk met literatuur. Kompleks 1 kristalliseer in `n ortorombiese kristalstelsel en ruimtegroep Pbca, terwyl komplekse 2, 3a en 3b almal in `n monokliniese kristalstelsel en ruimtegroep P21/c, kristalliseer. Oor die algemeen is dit waargeneem dat hierdie mono-gesubstitueerde β-diketonato komplekse van niobium(V) in `n verwronge oktahedriese koördinasie polyheder kristalliseer. Die gemiddelde O-Nb-O bythoek en Nb-O bindingsafstand vir hierdie komplekse is onderskeidelik as 80.5 (1) °en 2.108 (2) Å bepaal. `n Kinetiese ondersoek is uitgevoer om die vorming van die (asetielasetonato-κ 2 - O,O’)chloridotrimetoksidoniobium(V)kompleks in methanol te volg. Die koördinasie- meganisme is gepostuleer vir die twee waargenome stappe van acacH koördinasie, waarvan die aanvanklike koördinasie van die ligand in die eerste stap plaasvind. Die ewewigskonstante, K1, is as 1975 (201) M -1 teen 25.0 °C bepaal. Die tweede, tempo- bepalende stap is verteenwoordigend van die totale reaksie en sluit die ring-sluiting van die acac ligand in, en lewer K1 as 1403 (379) M -1 op. Binne eksperimentele fout stem hierdie waarde goed ooreen met die waarde van die eerste stap. Wanneer die tempokonstantes, k1 en k2, vergelyk word is, gevind dat die eerste reaksie ongeveer ses ordegroottes (10 6 ) vinniger as die stadiger, tweede reaksie stap is. VIII
Opsomming 93 Nb KMR is met sukses gebruik in die karakterisering van die bereide niobium(V) produkte en speel `n belangrike rol in die kinetiese studie van die projek. Met betrekking tot die kinetiese studie vind oplosmiddel-koördinasie vinnig plaas met oplossing van die dimeriese reagens, [NbCl5]2, in methanol en die niobium(V) reagens is korrek vasgestel as [NbCl2(OMe)3(MeOH)] deur middel van 93 Nb KMR. IX
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: Abstract 93 Nb NMR was successfully
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)]:
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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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