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

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

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4.5 Crystal Structure of [NbCl2(phacac-К 2 -O,O’)(OMe)3] and [NbCl(phacac-К 2 - O,O’)(OMe)2] ...................................................................................................... 71 4.5.1 Introduction ................................................................................................ 71 4.6 Conclusion ....................................................................................................... 77 5 Formation kinetics of [NbCl(acac)(OMe)3] ....................................... 79 5.1 Introduction ...................................................................................................... 80 5.2 Experimental procedures ................................................................................. 80 5.2.1 Kinetic experiments ................................................................................... 80 5.2.2 93 Nb NMR .................................................................................................. 81 5.3 Results and Discussion ................................................................................... 84 5.3.1 Proposed Reaction Scheme ...................................................................... 84 5.3.2 Stepwise analysis of the reaction scheme ................................................. 85 5.3.3 Derivation of the rate law ........................................................................... 88 5.3.1 Discussion ................................................................................................. 89 5.4 Conclusion ....................................................................................................... 93 6 Evaluation of Study ........................................................................... 95 6.1 Results Obtained .............................................................................................. 95 6.2 Future Research .............................................................................................. 96 Appendix A………………………………………………………….….……... 97 Appendix B…….……………………………………………………..……....114 IV

Abbreviations and Symbols Abbreviation Meaning thd - V Tetramethylheptanedionate acacH Acetylacetone phacacH 1-phenyl-1,3-butanedione tBu2(acacH) Di-tertiarybutylacetylacetone ttbd - 1,1,1-trifluoro-4-thenoyl-2,4-butanedionate hfacacH Hexafluoroacetylacetone tropH Tropolone dbm Dibenzoylmethanato IR Infra red UV/Vis Ultraviolet/visible NMR Nuclear magnetic resonance XRD X-ray diffraction Z Number of formula units in a unit cell A Absorbance (theoretical) Aobs Observed absorbance (L,L') Bidentate ligand kx k-x Kx kobs ppm DMF THF C6D6 CD3OD ν λ ∆H ≠ ∆S ≠ mg mmol M Rate constant for a forward equilibrium reaction Rate constant for a backward equilibrium reaction Equilibrium constant for an equilibrium reaction Observed rate constant (Unit of chemical shift) parts per million Dimethyl formamide Tetrahydrofuran Deuterated benzene Deuterated methanol IR stretching frequency UV/Vis wavelength Enthalpy of activation Entropy of activation Milligram Millimol mol.dm -3

Abbreviations <strong>and</strong> Symbols<br />

Abbreviation Meaning<br />

thd -<br />

V<br />

Tetramethylheptanedionate<br />

acacH Acetylacetone<br />

phacacH 1-phenyl-1,3-butanedione<br />

tBu2(acacH) Di-tertiarybutylacetylacetone<br />

ttbd -<br />

1,1,1-trifluoro-4-thenoyl-2,4-butanedionate<br />

hfacacH Hexafluoroacetylacetone<br />

tropH Tropolone<br />

dbm Dibenzoylmethanato<br />

IR Infra red<br />

UV/Vis Ultraviolet/visible<br />

NMR Nuclear magnetic resonance<br />

XRD X-ray diffraction<br />

Z Number <strong>of</strong> formula units in a unit cell<br />

A Absorbance (theoretical)<br />

Aobs Observed absorbance<br />

(L,L') Bidentate lig<strong>and</strong><br />

kx<br />

k-x<br />

Kx<br />

kobs<br />

ppm<br />

DMF<br />

THF<br />

C6D6<br />

CD3OD<br />

ν<br />

λ<br />

∆H ≠<br />

∆S ≠<br />

mg<br />

mmol<br />

M<br />

Rate constant for a forward equilibrium reaction<br />

Rate constant for a backward equilibrium reaction<br />

Equilibrium constant for an equilibrium reaction<br />

Observed rate constant<br />

(Unit <strong>of</strong> chemical shift) parts per million<br />

Dimethyl formamide<br />

Tetrahydr<strong>of</strong>uran<br />

Deuterated benzene<br />

Deuterated methanol<br />

IR stretching frequency<br />

UV/Vis wavelength<br />

Enthalpy <strong>of</strong> activation<br />

Entropy <strong>of</strong> activation<br />

Milligram<br />

Millimol<br />

mol.dm -3

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