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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2.4.8 Cyclopentadienes ...................................................................................... 17<br />
2.4.9 Phosphates ................................................................................................ 17<br />
2.5 Niobium as Catalyst ......................................................................................... 18<br />
2.6 β-diketone Complexes <strong>of</strong> Niobium ................................................................... 20<br />
2.6.1 Tetrakis(β-diketonate) <strong>niobium</strong>(IV) <strong>complexes</strong> .......................................... 21<br />
2.6.1.1 [Nb(thd)4].............................................................................21<br />
2.6.1.2 [Nb(hfacac)4]........................................................................22<br />
2.6.2 Bis(β-diketonate) <strong>niobium</strong>(IV) <strong>complexes</strong> .................................................. 23<br />
2.6.2.1 trans-[NbCl2(thd)2]...............................................................23<br />
2.6.3 Mono(β-diketonate) <strong>niobium</strong>(V) <strong>complexes</strong> ............................................... 24<br />
2.6.3.1 fac-[Nb(NCS)(Opr)3(dbm)] <strong>and</strong> trans-[Nb<br />
(NCS)2(OEt)2(dbm)].............................................................24<br />
2.6.3.2 [Nb(OEt)4(dbm)]...................................................................25<br />
2.6.3.3 [NbCl3O(ttbd) - ].....................................................................26<br />
2.6.3.4 trans-[NbCl2(OEt)2(dbm)].....................................................26<br />
2.6.4 Bridged <strong>niobium</strong> β-diketonate <strong>complexes</strong> .................................................. 27<br />
2.6.4.1 [Nb2(µ-S2)2(acac)4] <strong>and</strong> [Nb2(µ-S2)(acac)4]..........................27<br />
2.6.4.2 [Sr2Nb2O(thd)3(OEt)9(EtOH)3] <strong>and</strong><br />
[Sr2Nb2O(thd)3(O n Pr)9( n PrOH)3]...........................................28<br />
2.7 Alkoxides .......................................................................................................... 30<br />
2.7.1 Preparation <strong>of</strong> Metal alkoxides .................................................................. 30<br />
2.7.2 Niobium alkoxides ..................................................................................... 32<br />
2.7.3<br />
93 Nb NMR Studies ..................................................................................... 33<br />
2.8 Kinetic Studies <strong>of</strong> Niobium Complexes ............................................................ 36<br />
2.9 Conclusion ....................................................................................................... 41<br />
3 Synthesis <strong>and</strong> Characterisation <strong>of</strong> Niobium(V) Complexes ........... 42<br />
3.1 Introduction ...................................................................................................... 42<br />
3.2 Nuclear Magnetic Resonance Spectroscopy (NMR) ........................................ 42<br />
3.3 Ultraviolet-visible Spectroscopy (UV/Vis) ......................................................... 45<br />
II