| dc.description.abstract | Chapter one provides a brief exposition on the history and importance of boron and
carboranes and introduces 1,1ʹ-bis(o-carborane). It also provides literature examples of
1,1ʹ-bis(o-carborane) chelates, 1,1ʹ-bis(o-carboranyl)phosphines and tethered 1,1ʹ-bis(o
carboranes).
Chapter two discusses the reaction between dilithiated 1,1ʹ-bis(o-carborane) and di
halogenated ruthenium compounds to afford several new compounds of the formula
[Ru(κ2/3-2,2ʹ(3ʹ)-{1-(1ʹ-1ʹ,2ʹ-closo-C2B10H10)-1,2-closo-C2B10H10})(L)]. The first
compound prepared, whereby L = p-cymene, reacts with either PPh3 or dppe and shows
unusual displacement of the p-cymene ligand and a change in the bonding mode of 1,1ʹ
bis(o-carborane). The fully saturated (MeCN or CO) derivatives of these compounds are
also synthesised and studied, some of which are excellent examples of illustrating the
structural trans effect. The initial {Ru(p-cymene)} was tested as a catalyst and displayed
good Lewis acid catalytic activity of a Diels-Alder cycloaddition.
Chapter three explores two carboranylphosphines [µ-2,2ʹ-PR-{1-(1ʹ-1ʹ,2ʹ-closo
C2B10H10)-1,2-closo-C2B10H10}], where R = Et or Ph. Two-dimensional NMR
spectroscopy and DFT calculations are used to explain an unusual lack of observed 2JPH
coupling in the 1H NMR spectrum of the ethyl derivative. Their subsequent reactions
with {AuCl} and {Se} are also discussed as they provide a route to identifying the steric
bulk and electronic properties of these carboranylphosphines.
Chapter four discusses one new tethered 1,1ʹ-bis(o-carborane) and its comparison with
non-carborane analogues. A known tethered carborane is also synthesised and its single
decapitation and metalation with {Ru(p-cymene)} explored producing the desired 12
vertex ruthenacarborane/12-vertex carborane but also an unusual 13-vertex
diruthenacarborane/12-vertex carborane.
Chapter five gives all the synthetic and analytical details for the compounds discussed.
Appendix one provides crystallographic tables and appendix two provides all the
crystallographic information on a CD. Appendix three includes copies of all published
work related to this thesis (to date). | en |
