The strength and selectivity of commercial phenolic oxime copper extractants are thought to be due to the hydrogen-bonded <i>pseudo</i>-macrocycle which this ligand forms around copper. This thesis investigates the role of hydrogen-bonding of sulfonamido ligands to determine the importance of ligand association prior to and upon complexation. Chapter 2 deals with the coordination chemistry of a series of 11 relatively simple bidentate monosulfonamidodiamine ligands. The solid state structures of these ligands are difficult to predict and illustrate that a surfeit of hydrogen-bond donors and acceptors incorporated into a relatively flexible ligand leads to a variety of hydrogen-bond interactions in the solid-state and hence a range of complicated secondary structures are observed including two and three dimensional arrays. However, these ligands do form <i>pseudo</i>-macrocycles around copper and nickel(II) centres. These ligands were found to be quite weak (pH_1/2 4-6) extractants when used in pH-swing process. Increasing the size of the chelate ring from five to six leads to even weaker extractants. In Chapter 3 the synthesis and characterisation of a series of 6 sulfonamido-oxime ligands which have a similar backbone to the commercial <i>ortho</i>-phenolic oximes are described. The majority of solid-state structures contain hydrogen-bonded dimers and appear to have structures which are independent of small substituent changes in the ligand. However the <i>E, Z</i> isomerisation of the oxime is important. The <i>Z</i> isomer only forms polymeric species. Complex formation by the sulfonamido-oxime ligands is less predictable than with the monosulfonamidodiamines and both 2:1 and 1:1, ligand to metal complexes are observed. In addition to the expected bonding of the sulfonamido and oximic nitrogen atoms, the bonding of the sulfonamido oxygen atoms and the deprotonated oximic oxygen atom to metal ions is also observed. Investigation of the solution chemistry of the monosulfonamidodiamine and the sulfonamido-oxime ligands are considered in Chapter 4. ESI-MS shows evidence for dimer formation and ¹H nmr, VPO and IR analyses show that self-association occurs in solution and is very concentration, temperature and solvent dependent. This chapter also discusses the development of monosulfonamidodiamine and sulfonamido-oxime ligands with higher solubility in solvents of low polarity such as toluene. The possibility of developing sulfinamido ligands is also discussed covering the synthesis of sulfinyl chlorides and the attempted preparation of prototype sulfinamido ligands. Chapter 5 deals with the development of <i>pseudo-</i>macrocyclic and <i>pseudo</i>-cage structures using ternary metal/sulfonamide/amine systems. <i>Bis- </i>and <i>tris-</i>sulfonamido ligands have been synthesised and their solid state structures were investigated. The formation of metal complexes of these ligands proved difficult and no ternary complexes were isolated.

An introduction to macrocyclic chemistry, with particular emphasis on [9]aneS<SUB>3</SUB> (1,4,7 - trithiacyclononane) and thioether macrocyclic transition metal complexes of groups VIII and IX is presented. The reaction of [RuC1<SUB>2</SUB>(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)] with TIPF<SUB>6</SUB> in CH<SUB>2</SUB>C1<SUB>2</SUB> at 298K results in the formation of a mixture of complexes, [Ru(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)(μ-C1)]<SUB>2</SUB>(PF<SUB>6</SUB>)<SUB>2</SUB> and [Ru(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)(μ-C1)<SUB>2</SUB>T1]<SUB>2</SUB>(PF<SUB>6</SUB>)<SUB>2</SUB>, which have been both characterised by X-ray crystallography. The synthesis of pure [Ru(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)(μ-C1)]<SUB>2</SUB>(PF<SUB>6</SUB>)<SUB>2</SUB> and [Ru(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)(μ-C1)<SUB>2</SUB>T1]<SUB>2</SUB>(PF<SUB>6</SUB>)<SUB>2</SUB> is described. Both complexes react with acetonitrile to form [Ru(NCCH<SUB>3</SUB>)C1(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>). The reaction of [RuC1<SUB>2</SUB>(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)] with TIPF<SUB>6</SUB> in CH<SUB>3</SUB>NO<SUB>2</SUB> leads to the isolation of the complexes [Ru(NCCH<SUB>2</SUB>CH<SUB>3</SUB>)C1(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>) and [RuC1(NC<SUB>3</SUB>H<SUB>3</SUB>O)(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>). The X-Ray structure of the latter complex is described. The complexes form by reacting with two impurities (ethyl cyanide and isoxazole) present in CH<SUB>3</SUB>NO<SUB>2</SUB>. The addition of TIPF<SUB>6</SUB> TO [RuC1<SUB>2</SUB>(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)] in CH<SUB>3</SUB>NO<SUB>2</SUB> and THT forms the complex [Ru(C1(PPh<SUB>3</SUB>)(THT)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>). The single crystal X-ray structure of this complex reveals the presence of a 1:1 mixture of the THT complex, [Ru(C1(PPh<SUB>3</SUB>)(THT)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>) and a THT-S-oxide complex, [Ru(C1(PPh<SUB>3</SUB>)(THT-S-oxide)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>). The THT-S-oxide complex forms during crystallisation.

This thesis describes the formation of iridium fluoroacyl compounds by reaction of XeF<SUB>2</SUB> with Ir(I) compounds, and the reactivity of some of these fluoroacyl species. Reactions of [Ir(CO)<SUB>3</SUB>L<SUB>2</SUB>][AsF<SUB>6</SUB>] with XeF<SUB>2</SUB> led to the fluoroacyl compounds [Ir(CO)<SUB>2</SUB>(COF)FL<SUB>2</SUB>][AsF<SUB>6</SUB>] for L = PEt<SUB>3</SUB>, PMe<SUB>3</SUB>, PMe<SUB>2</SUB>Ph, PEt<SUB>2</SUB>Ph and PEtPh<SUB>2</SUB> but not for L = PMePh<SUB>2</SUB>, PPh<SUB>3</SUB> and PCy<SUB>3</SUB>. Reactions of [IR(CO)(PMe<SUB>3</SUB>)<SUB>4</SUB>][Cl] and IR(CO)<SUB>2</SUB>Cl(PMe<SUB>3</SUB>)<SUB>2</SUB> with XeF<SUB>2</SUB> led to fluoroacyl containing iridium compounds but reaction of IR(CO)<SUB>2</SUB>Cl(PPh<SUB>3</SUB>)<SUB>2</SUB> with XeF<SUB>2</SUB> did not. Reaction of [IR(CO)<SUB>2</SUB>(COF)F(PEt<SUB>3</SUB>)<SUB>2</SUB>][BF<SUB>4</SUB>] with SiH<SUB>3</SUB>CN, SiH<SUB>3</SUB>NCS and SiH<SUB>3</SUB>NCO led to the complexes [IR(CO)<SUB>2</SUB>(C(O)X)D(PEt<SUB>3</SUB>)<SUB>2</SUB>][BF<SUB>4</SUB>], X = CN, NCS, NCO. SiH<SUB>3</SUB>N(PF<SUB>2</SUB>)<SUB>2</SUB>, SiH<SUB>3</SUB>NMe<SUB>2</SUB>, Me<SUB>3</SUB>SiH, Me<SUB>3</SUB>SiCl and SiH<SUB>3</SUB>Br were also reacted with [Ir(CO)<SUB>2</SUB>(COF)F(PEt<SUB>3</SUB>)<SUB>2</SUB>][BF<SUB>4</SUB>].Reaction of [Ir(CO)<SUB>2</SUB>(COF)F(PEt<SUB>3</SUB>)<SUB>2</SUB>[BF<SUB>4</SUB>] with BF<SUB>3</SUB> gave [Ir(CO<SUB>3</SUB>F(PEt<SUB>3</SUB>)<SUB>2</SUB>[BF<SUB>4</SUB>]<SUB>2</SUB>. This compound was reacted with NMe<SUB>3</SUB>, PMe<SUB>3</SUB>, SMeEt, Pr<SUB>4</SUB>NCl, LiAl(OBu<SUP>t</SUP>)<SUB>3</SUB>H, PEt<SUB>3</SUB> and AsH<SUB>3</SUB>. In these reactions there was evidence for both nucleophilic attack at coordinated carbonyl ligands and for fluoride migration onto a carbonyl ligand. Products were characterised using <SUP>19</SUP>F, <SUP>31</SUP>P, <SUP>13</SUP>C and <SUP>1</SUP>H n.m.r. spectroscopy using suitable isotopic enrichments where appropriate. When isolated, products were further characterised by I.R. spectroscopy.

Chapter 1: A general discussion of macrocyclic co-ordination chemistry is given, with particular emphasis on the biological and catalytic relevance of macrocyclic systems. Chapter 2: Reproducible high yield synthesis of [Au ([9]aneS<SUB>3</SUB>)<SUB>2</SUB>](PF<SUB>6</SUB>) and [Au([9]aneS<SUB>3</SUB>)<SUB>2</SUB>](BF<SUB>4</SUB>)<SUB>2</SUB> have been established. [Au([9]aneS<SUB>3</SUB>)<SUB>2</SUB>]<SUP>2</SUP>+ undergoes a one-electron oxidation to Au(III) and an irreversible reduction to Au(I). The solution e.p.r. spectrum of [Au([9]aneS<SUB>3</SUB>)<SUB>2</SUB>]<SUP>2</SUP>+ shows an isotropic signal with hyperfine coupling to <SUP>197</SUP>Au. The frozen glass e.p.r. spectrum depicts a complicated anisotropic signal. Attempted e.p.r. spectrum simulation suggested that the quadrupole and nuclear Zeeman interactions are significant in [Au([9]aneS<SUB>3</SUB>)<SUB>2</SUB>]<SUP>2</SUP>&43 , consistent with the <SUP>197</SUP>Au Mossbauer data recorded for Au(II) complex. The stable Au(I) complex, [Au(PPh<SUB>3</SUB>)([9]aneS<SUB>3</SUB>)](PF<SUB>6</SUB>) was also prepared. Chapter 3: [Au([18]aneS<SUB>6</SUB>)[(PF<SUB>6</SUB>) was isolated and structurally characterised; [18]aneS<SUB>6</SUB> binds the Au(I) centre in a [2+ 2] distorted tetrahedral co-ordination. This complex exhibits two quasi-reversible oxidations, which were assigned as being largely metal-based processes by e.p.r. spectroscopy. Electrogenerations of the Au(II) and Au(III) species were monitored by electronic absorption spectroscopy, which demonstrated the absence of any transient intermediates. The electron-transfer rate constant determined for the [Au([18]aneS<SUB>6</SUB>)]<SUP></SUP>+ /2&43 couple indicates that a large stereochemical change accompanies the oxidation of Au(I) and Au(II). Direct synthesis of [Au([18]aneS<SUB>6</SUB>)](PF<SUB>6</SUB>)<SUB>2</SUB> was carried out. The solution e.p.r. spectrum of [Au([18]aneS<SUB>6</SUB>)](PF<SUB>6</SUB>)<SUB>2</SUB> in MeNO<SUB>2</SUB>, at 293K shows an isotropic signal; a complicated isotropic signal is observed at 77K. On the basis of e.p.r. and electronic absorption spectra the geometry of [Au([18]aneS<SUB>6</SUB>)]<SUP>2</SUP>+ was proposed to be distorted octahedral. Chapter 4: The Au(I) complex of [15]aneS<SUB>5</SUB> was isolated. [Au([15]aneS<SUB>5</SUB>)](B(C<SUB>6</SUB>F<SUB>5</SUB>)<SUB>4</SUB>) and [Au(15]aneS<SUB>5</SUB>)](PF<SUB>6</SUB>) are both dimeric in the solid-state, with the Au(I) centres in [2+ 2] distorted tetrahedral stereochemistries and bound in an exocyclic manner between the two facial macrocycles. [Au([15]aneS<SUB>5</SUB>]<SUP>2</SUP>+ exhibits two solvent dependent quasi-reversible oxidations, which were assigned as largely metal-based processes. The electron-transfer rate constant, k<SUB>s</SUB>, for the first oxidation was determined. Electrogenerations of the Au(II) and Au(III) species were monitored using the O.T.E. technique. [Au([15]aneS<SUB>5</SUB>)](PF<SUB>6</SUB>)<SUB>2</SUB> was synthesised and was found to be monomeric in solution. An isotropic e.p.r. spectrum was observed for [Au([15]aneS<SUB>5</SUB>)]<SUP>2</SUP>+ in MeNO<SUB>2</SUB> solution. A solvent independent rhombic signal was recorded at 77K, the d<SUP>9</SUP> centre is therefore in an unsymmetrical environment. The dimeric [Au([15]aneS<SUB>5</SUB>)]<SUP></SUP>+ solid must either immediately dissociate on solvation or prior to or on oxidation to [Au([15]aneS<SUB>5</SUB>)]<SUP>2</SUP>+ .

The synthesis, structures and physical properties of tripodal and macrocyclic Schiff base ligands and their complexes are described. All ligands are synthesised by the condensation of amines with 2,6-diformyl- or 2,6-diacetyl-phenols. The synthesis of a novel dodecadentate tripodal Schiff base ligand, L<SUP>1</SUP>H<SUB>3</SUB>, is described. Reaction of L<SUP>1</SUP>H<SUB>3</SUB> with Ln(ClO<SUB>4</SUB>)<SUB>3</SUB> where Ln=La, Pr gives complexes of the form [Ln(L<SUP>1</SUP>H<SUB>3</SUB>)(H<SUB>2</SUB>O)](CIO<SUB>4</SUB>)<SUB>3</SUB> and where Ln=Y, [Y(L<SUP>1</SUP>H<SUB>3</SUB>)](CIO<SUB>4</SUB>)<SUB>3</SUB>. The single crystal X-ray structures of L<SUP>1</SUP>H<SUB>3</SUB> and complexes are described. L<SUP>1</SUP>H<SUB>3</SUB> reacts with Gd(CIO<SUB>4</SUB>)<SUB>3</SUB> in the presence of Cu(CIO<SUB>4</SUB>)<SUB>2</SUB> and N,N-diisopropyl-ethylamine resulting in hydrolysis of the acetal functionality to give a complex of the nonadentate tripodal ligand L<SUP>5</SUP>H<SUB>3</SUB>, [Gd(L<SUP>5</SUP>H<SUB>3</SUB>)(H<SUB>2</SUB>O)<SUB>2</SUB>](CIO<SUB>4</SUB>)<SUB>3</SUB>, the single crystal X-ray structure of which is described. A similar reaction occurs with Ni(CIO<SUB>4</SUB>)<SUB>2</SUB>, giving [Ni(L<SUP>5</SUP>H<SUB>3</SUB>)](CIO<SUB>4</SUB>)<SUB>2</SUB>, The X-ray structure of which is also described. The preparation of L-H<SUB>3</SUB>, a related tripodal nonadentate ligand, is described and the structure determined by single crystal X-ray analysis. Complexes prepared by reaction with M(CIO<SUB>4</SUB>)<SUB>2</SUB>, M=Ni, Zn, are of the form [M(L<SUP>2</SUP>H<SUB>3</SUB>)](CIO<SUB>4</SUB>)<SUB>2</SUB> and the single crystal X-ray structures show the two complexes are isostructural. The Schiff base macrocycle [L<SUP>3</SUP>H<SUB>4</SUB>](PF<SUB>6</SUB>)<SUB>2</SUB> reacts to form [Cu<SUB>2</SUB>L<SUP>3</SUP>(CH<SUB>3</SUB>CO<SUB>2</SUB>)]Br preferentially in the presence of La(CIO<SUB>4</SUB>)<SUB>3</SUB> and Cu(CH<SUB>3</SUB>CO<SUB>2</SUB>)<SUB>2</SUB>. The single crystal X-ray structure is described. A template condensation of 2,6-diformyl-4-methylphenol and tris(2-amino-ethyl)amine around yttrium(III) yields a complex of the macrobicyclic ligand. L<SUP>6</SUP>H<SUB>3</SUB>, [Y(L<SUP>6</SUP>H<SUB>3</SUB>)(H<SUB>2</SUB>O)<SUB>2</SUB>](CIO<SUB>4</SUB>)<SUB>3</SUB>, the single crystal X-ray structure of which is described. [La(L<SUP>6</SUP>H<SUB>3</SUB>)(H<SUB>2</SUB>O)](CIO<SUB>4</SUB>)<SUB>3</SUB> was further reacted with Ni(CIO<SUB>4</SUB>)<SUB>2</SUB> in the presence of N,N-diisopropylethylamine to form the heterobimetallic complex [LaNi(L<SUP>1</SUP>)(H<SUB>2</SUB>O)](CIO<SUB>4</SUB>)<SUB>2</SUB>, the structure of which was confirmed by single crystal X-ray analysis. Preliminary magnetic studies on the complex [GdNi(L<SUP>1</SUP>)](CIO<SUB>4</SUB>)<SUB>2</SUB> indicate a weak ferromagnetic coupling between the metals.

An introduction to macrocyclic chemistry is presented, with particular emphasis on 1,4,7-triazacyclononane ([9]aneN<SUB>3</SUB>) and the addition of pendent groups to this macrocycle. Reaction of [9]aneN<SUB>3</SUB>, with (CH<SUB>3</SUB>O)<SUB>2</SUB>CHNMe<SUB>2</SUB> yields 1,4,7-triazatricyclo[5.2.1.0<SUP>4,10</SUP>] decane, the single crystal X-ray structure of which is described. Acidic hydrolysis of 1,4,7-triazatricyclo[5.2.1.0<SUP>4.10</SUP>]decane yields 1-formyl-1,4,7-triazacyclononane (HOC[9]aneN<SUB>3</SUB>), the single crystal X-ray structure of which is also described. Further reaction of HOC[9]aneN<SUB>3</SUB>, with excess isobutylene oxide affords 1-formyl-4,7-<I>bis</I>(2-hydroxy-2-methylpropyl)-1,4,7-triazacyclononane (L<SUP>2</SUP>H<SUB>2</SUB>), which yields 1,4-<I>bis</I>(2-hydroxy-2-methylpropyl)-1,4,7-triazacyclononane upon basic hydrolysis. The single crystal X-ray structure of 1,4-<I>bis</I>(2-hydroxy-2-methylpropyl)-1,4,7-triazacyclononane is reported. The reaction of 1,4,7-triazatricyclo[5.2.1.0<SUP>4,10</SUP>]decane with PhCH<SUB>2</SUB>Br yields 1-benzyl-1,4,7-triazacyclononane (L<SUP>4</SUP>), which reacts further with isobutylene oxide to yield 1-benzyl-4,7-<I>bis</I>(2-hydroxy-2-methylpropyl)-1,4,7-triazacyclononane (L<SUP>6</SUP>H<SUB>2</SUB>). Reaction of [9]aneN<SUB>3</SUB> with HCOOH and CH<SUB>3</SUB>CO<SUB>2</SUB>OCH<SUB>3</SUB> yields 1,4,7-triazacyclononane, the single crystal X-ray structure of which is described. Analogously, reaction of [9]aneN<SUB>3</SUB> with PhCOCI yields 1,4,7-tribenzoyl-1,4,7-triazacyclononane, the single crystal X-ray structure of which is also described. The ring conformations of these two molecules are found to be similar, both adopting a [333] conformation. Reaction of Pd(OAc)<SUB>2</SUB> with HOC[9]aneN<SUB>3</SUB> in CH<SUB>2</SUB>CI<SUB>2</SUB> affords the species [Ph(HOC[9]aneN<SUB>3</SUB>)<SUB>2</SUB>][B(C<SUB>6</SUB>F<SUB>5</SUB>)<SUB>4</SUB>]<SUB>2</SUB>.2H<SUB>2</SUB>O, the single crystal X-ray structure of which shows the cations to form a 'chain' structure with interchelated H<SUB>2</SUB>O molecules. Reaction of Ni(BF<SUB>4</SUB>)<SUB>2</SUB>.6.5CH<SUB>3</SUB>CH with excess HOC[9]aneN<SUB>3</SUB> in refluxing CH<SUB>3</SUB>CN leads to hydrolysis of the amide function and formation of the previously reported [Ni([9]aneN<SUB>3</SUB>)<SUB>2</SUB>]<SUP>2+</SUP>.

The acyl palladium complex (bpy)Pd(COMe)(I) (bpy = 2,2'-bipyridyl) was synthesised, and reacted with a variety of different alkenes, cyclic alkenes and dienes, and arenes in an attempt to yield the inserted acyl complexes {(bpy)Pd(C<SUB>x</SUB>R<SUB>Y</SUB>COMe)}. The inserted complexes were the first stage in setting up a catalytic reaction with the Palladium complex acting as a catalyst in the synthesis of an acylated arene. The osmium cluster Os<SUB>3</SUB>(CO)<SUB>10</SUB>(NCMe)<SUB>2</SUB>, was reacted with a series of functionalised arenes of the type C<SUB>6</SUB>H<SUB>4</SUB>R<SUP>1</SUP>R<SUP>2</SUP> (where R<SUP>1</SUP> = H, R<SUP>2</SUP> = F, Cl, Br, CHCH<SUB>3</SUB>, C(CH<SUB>3</SUB>)CH<SUB>2</SUB> and Me; R<SUP>1</SUP> = R<SUP>2</SUP> = Me, R<SUP>1 </SUP>= R<SUP>2</SUP> = C(CH<SUB>3</SUB>)CH<SUB>2</SUB>) yielding clusters of the type Os<SUB>3</SUB>(CO)<SUB>9</SUB>H<SUB>2</SUB>(C<SUB>6</SUB>H<SUB>2</SUB>R<SUP>1</SUP>R<SUP>2</SUP>). The crystallographic and spectroscopic data provides evidence of the different geometric forms that the complexes demonstrate with the different types of ligands. The osmium arene complexes were reacted further using a Friedel-Crafts acylation reaction to acylate the arene ring when it is attached to the cluster. The resultant complexes show a shifting of the IR bands in the IR to higher wavenumbers. The compound Os<SUB>3</SUB>(CO)<SUB>9</SUB>H<SUB>2</SUB>(C<SUB>2</SUB>H<SUB>3</SUB>F) reacted with 2-butyne yielding the complexes Os<SUB>3</SUB>(CO)<SUB>8</SUB>(H)(CH<SUB>2</SUB>CHCHCH<SUB>3</SUB>)(C<SUB>6</SUB>H<SUB>3</SUB>F) and Os<SUB>3</SUB>(CO)<SUB>8</SUB>H<SUB>2</SUB>(η<SUP>2</SUP>-2-butyne)(C<SUB>6</SUB>H<SUB>3</SUB>F) which were identified crystallographically and spectroscopically. These two complexes show two different bonding modes of the butyne ligand to metal centre.

Transferrin is a bilobal glycoprotein with the function of transporting iron and other metal ions including diagnostic radioisotopes, therapeutic and toxic metal ions. A similar protein (ferric-ion-binding-protein) has also been found in several Gram-negative bacteria. An unexpectedly strong binding of Bi³⁺ (ionic radius 1.03Å) to the recombinant N-lobe of transferrin (hTF/2N) was found. The binding constant was calculated to be log K* 18.9± 0.2 at 310 K, 5 mM bicarbonate, 10 mM Hepes buffer at pH 7.4. This strong binding requires concomitant binding of a synergistic anion (carbonate) as proved by ¹³C NMR spectroscopy. Such a strong binding has led to the rationalization of the strength of metal binding to transferrin, which correlates well with metal acidity. Significantly this allowed the discovery of a new metal ion (Ti⁴⁺) binding to transferrin, which may be relevant to Ti⁴⁺ anticancer activity. 2D [¹H, ¹³C] NMR spectra of recombinant e-¹³C-Met labeled transferrin at very low concentration were obtainable within a short time. The selectivity of lobe loading with Bi³⁺ is compared with that of other metal ions (Fe³⁺, Al³⁺ and Ga³⁺) and preferential loading to the C-lobe was found. Bi³⁺ induced similar chemical shift changes of Met residues as those induced by Fe³⁺, Al³⁺ and Ga³⁺ suggesting similar structural changes of the protein, probably from lobe-open to lobe-closed form although the local structure (Trp128 patch) may slightly different upon binding of different metal ions. A site specific mutant I132M with e-¹³C-Met labeled hTF/2N was used as a model to investigate possible target sites for bismuth in blood plasma. Using the chemical shift changes of Met residues as a probe, it was found that bismuth could be recognized by transferrin in the presence of large excess of albumin (biologically relevant conditions) and even in intact blood plasma. Albumin has been previously thought to be a potential target site for bismuth due to its free cysteine (Cys34). However, bismuth only associates weakly with albumin. For the first time, a direct detection of metallodrug binding to a protein at biologically relevant concentrations without separation was achieved.

<i>Chapter 1</i> consists of a brief overview of transition metal cyclopentadienyl chemistry and of the chemistry of carbametallaborane species derived from [7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>]<SUP>2-</SUP>, with specific reference to the bonding modes commonly adopted by each ligand to transition metal fragments. The forms of the π-MO's of [C_5H_5]^-, [C_2B_9H_11]^2- and of the monoanionic ligand [9-SMe_2-7,8-C_2B_9H_10]^- (or [carb']^-), as obtained by extended Huckel molecular orbital (EHMO) calculations, are also presented. In <i>Chapter 2</i>, the structure of [7,8-C_2B_9H_12]^-, (1), is presented, showing an <i>endo</i> -H atom, rather than the commonly accepted μ-H, associated with the open ligand face. This result is supported by those of n.m.r. and theoretical studies. Isolobal replacement of the <i>endo</i>-terminal hydrogen atom by a (PPh<SUB>3</SUB>Au<SUP></SUP>+ ) fragment leads to complex (2), [10-<i>endo</i>-(PPh<SUB>3</SUB>Au)-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>]<SUP>-</SUP>, which has also been studied crystallographically. Structural trends within the series (1), (2) and [PPh<SUB>3</SUB> Cu(C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>)]<SUP>-</SUP> have been rationalised <i>via</i> the results of EHMO calculations. <i>Chapter 3</i> presents the structure of [10,11-μ-H-9-SMe_2-7,8-<i>nido</i>-C_2B_9H_10], (3), the protonated precursor to the monoanionic ligand [carb']^-. The molecule possesses an asymmetric bridging H atom on its open face, a structural feature whose origin may be traced using MO calculations at the extended Huckel level. The (triphenylphosphine)gold(I) and (triphenylphosphine)copper(I) derivatives of [carb']^-, (4) and (5), have been prepared, and their structures determined by X-ray methods. In all three compounds, the SMe_2 substituent appears to adopt a preferred conformation, and it is suggested that this is allied to an intramolecular electrostatic interaction. Analysis of structural patterns within (3), (4) and (5) reveals different trends to those observed for the related series in the previous chapter. These differences may be rationalised by frontier MO considerations.

This thesis describes the formation of some iridium complexes which contain an -SF<SUB>3</SUB> group. Although monosubstituted derivatives of SF<SUB>4</SUB> have been reported in organic chemistry, the -SF<SUB>3</SUB> ligand was previously unknown in transition metal complex chemistry. The first iridium complex containing an -SF<SUB>3</SUB> ligand was the product of reaction between <i>t</i>-IrCl(CO)[P(CH<SUB>2</SUB>CH<SUB>3</SUB>)<SUB>3</SUB>]<SUB>2</SUB> and SF<SUB>4</SUB>, the reaction being carried out in a d<SUB>2</SUB>-dichloromethane solution. As a result of variable temperature <SUP>19</SUP>F(<SUP>i</SUP>H) and <SUP>31</SUP>P[<SUP>i</SUP>H] n.m.r. studies, this complex was found to possess fluxionality at the -SF<SUB>3</SUB> site and also to undergo fluorine exchange by an intermolecular mechanism. These processes were found to be influenced by the presence of HF. Further information about factors influencing this exchange was obtained from other halo- and pseudohalo-complexes containing the -SF<SUB>3</SUB> group. Complexes with different phosphines (both alkyl and aryl) were also synthesized and investigated. Additional experiments showed that BF<SUB>3</SUB> removes a fluoride from sulphur to generate a novel -SF<SUB>2</SUB> ligand, which is isoelectronic with -PF<SUB>2</SUB>. The -SF<SUB>2<SUP></SUB></SUP>+ group can undergo nucleophilic substitution reactions with specific reagents, for example methanol, ethanol, CH<SUB>3</SUB>OSi(CH<SUB>3</SUB>)<SUB>3</SUB> and (H<SUB>3</SUB>C)<SUB>2</SUB>NSi(CH<SUB>3</SUB>)<SUB>3</SUB>. The structure of the adduct formed between SF<SUB>4</SUB> and trimethylamine [N(CH<SUB>3</SUB>)<SUB>3</SUB>] has been determined from solution <SUP>19F[</SUP>^1H] n.m.r. studies. This has effectively resolved the problem of previous conflicting reports on the structure and doubts as to the existence of this species. Finally, the crystal structures of two complexes produced during the course of this work are reported. The compounds concerned are:- a new form of <i>t</i>-IrCl(CO)[P(C_6H_5)_3]_2 into which two d_2-dichloromethane molecules have been incorporated in the crystal lattice.- a sulphur dioxide SO_2, adduct of this complex unsolvated. The crystal structure of this compound has been previously reported, but was found to have different unit cell parameters.