The reactions of some reagents containing fluorine, with a range of platinum and iridium complexes are described. These reactions were monitored by variable-temperature <SUP>19</SUP>F and <SUP>31</SUP>P nuclear magnetic resonance spectroscopy. Initial parts of the work are concerned with the reactions of AsF<SUB>3</SUB>, with PtHX(PEt<SUB>3</SUB>)<SUB>2</SUB> (X = Cl, Br or I). Several species were observed during the course of the reactions, the most interesting of which was a novel AsF<SUB>2</SUB> bridged binuclear platinum species. All products were characterised using multinuclear NMR. Suggestions for possible mechanisms are also given. The second main area of study was the reactions of some difluorophosphinepseudohalides with various platinum metal complexes. The reactions of PF<SUB>2</SUB>X (X = NCO, NCS) with a range of iridium and platinum cations, anions and neutral complexes are described. In addition, the reactions of these fluorine-containing reagents with some transition metal dimers are also investigated.

The thesis commences with a general introduction outlining the attraction of arene clusters and develops the area pertinent to the research described thereafter. An account of the synthesis, characterisation and reactivity of a series of cyclohexadiene and benzene clusters derived from the pentanuclear cluster Ru<SUB>5</SUB>C(CO)<SUB>15</SUB> is given. Encompassed within this work are investigations concerned with benzene migration and mechanisms by which 1,4-dienes isomerise to 1,3-dienes. A new stepwise route to the <I>bis</I>-benzene cluster Ru<SUB>6</SUB>C(CO)<SUB>11</SUB>(<I>η<SUP>6</SUP>-</I>C<I><SUB>6</SUB></I>H<SUB>6</SUB>)(<I>μ</I><SUB>3</SUB>-<I>η</I><SUP>2</SUP>:<I>η</I><SUP>2</SUP>:<I>η</I><SUP>2</SUP>-C<SUB>6</SUB>H<SUB>6</SUB>) is described, followed by a more general route to <I>bis</I>-arene clusters. Chemical characterisation and structural elucidation of a range of intermediate compounds and other arene and bis-arene species are chronicled. These include 'sandwich' clusters and a face-capping arene in a near-ecliped orientation. The five-membered aromatic ring systems [C<SUB>5</SUB>Me<SUB>5</SUB>]<SUP>-</SUP> and [C<SUB>5</SUB>H<SUB>5</SUB>]<SUP>-</SUP> are also described. Lastly, the crystal structures exhibited by arene clusters are examined. A co-crystal containing both a <I>mono</I>- and <I>bis</I>-arene species shows that the interactions found in independent crystals also dominate in the mixed system.

The development of photoactive molecular architectures is a recurring theme in supramolecular chemistry. In this respect, lanthanide complexes continue to play an important role owing to the attractive photophysical properties of the trivalent metal ion. Of particular interest are those complexes in which lanthanide luminescence is sensitised by the ligand, thereby combining many of the favourable characteristics inherent in both species. Work undertaken for this thesis involved the preparation and characterisation of lanthanide complexes and the study of the their luminescent properties; this work is divided into three sections. Firstly, it has been shown that imidodiphosphinates, acting as sensitising ligands, form a hydrophobic shell around lanthanide ions, to give long-lived, highly luminescent complexes. Modification of the imidodiphosphinate ligand allows the first coordination sphere of the metal to be altered, which prevents the binding of deactivating water molecules in solution. Secondly, reaction of a bis(b-diketonate) ligand with lanthanide ions leads to the formation of a novel triple-stranded dinuclear complex. The europium complex is very attractive, with a large absorption coefficient and high luminescence quantum yield. Finally, the ternary complex formation between lanthanide ions, lariat crown ethers and aromatic acids has been investigated with a view to the development of unique homogeneous immunoassay systems.

Non-toxic and stable photoactivatable platinum compounds, which can be activated by visible light to toxic anticancer drugs, could strongly reduce the side-effects shown by cisplatin by providing site-specific cancer treatment. In this thesis, the synthesis and characterisation of novel photoactive Pt amine compounds, which can be converted into reactive Pt species by visible light irradiation, are presented and their potential as photoactivatable prodrugs investigated.

Molecular mechanics techniques have been applied to the investigation of the formation of transition metal complexes. In addition to the determination of many relevant crystal structures, the two major projects carried out were: a) molecular structures within the crystalline forms of copper(I) ligated by phosphine and alkoxide or aryloxide ligands, and b) modes of extraction of salicylaldimine derivatives for metal salt transport. Copper(I) is observed to crystallise with phosphine and alkoxide or aryloxide ligands in five different structural motifs. The formation of these structural motifs was rationalised in terms of electronic and steric effects. Electronic effects were approximated to the pK_a of the alkoxide or aryloxide ligand. Steric effects were modelled using molecular mechanics calculations. Parameters for molecular mechanics were obtained from the Cambridge Structural Database. The results show that the formation of molecular structures can indeed be justified this way, and some structures have been predicted. Recently White and Tasker have proposed a novel method of "metal salt" extraction based on derivatives of the salicylaldimine ligand. The addition of pendant tertiary amines to this ligand allows the encapsulation of an anion, and thus transport of the entire "metal salt". This has been particularly successful for square planar copper(II) salts. Molecular mechanics calculations were employed to model the possible structures formed in the solution species to aid design of improved extractants for nickel(II). Parameters for molecular mechanics were obtained from the Cambridge Structural Database. The results enabled rationalisation of the poor performance of the original design, and the design of species with improved geometries for anion encapsulation.

No description available.

Chapter 1 describes the general area of carbaborane and carbametallaborane chemistry, with emphasis on characterisation and bonding, thus serving as an introduction to the work of the thesis. The chapter concludes with a brief description of the aims and scope of this work. Chapter 2 describes the synthesis and characterisation of <i>ether carbaboranes</i>, compounds in which one or both of the carbon atoms of a <i>closo</i> C<SUB>2</SUB>B<SUB>10</SUB> or a <i>nido</i> C<SUB>2</SUB>B<SUB>9</SUB> carbaborane cage are substituted with ether groups (such as -CH<SUB>2</SUB>OCH<SUB>3</SUB>). Emphasis is placed on the <SUP>11</SUP>B n.m.r. properties of such compounds; the <SUP>11</SUP>B n.m.r. spectra of several species are assigned (by <SUP>11</SUP>B-<SUP>11</SUP>B COSY n.m.r. and the application of empirical rules), the relative order of the resonances for each species are rationalised, and the ether groups are found to act as electron withdrawing groups. Also studied are the crystal and molecular structures of 1-(CH<SUB>2</SUB>OCH<SUB>3</SUB>)-1,2-<i>closo</i>-C<SUB>2</SUB>B<SUB>10</SUB>H<SUB>10</SUB>, 2, [BTMA][7-CH<SUB>2</SUB>OCH<SUB>3</SUB>)-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>11</SUB>], 5, and (thf)<SUB>2</SUB>Li[7,8-(CH<SUB>2</SUB>OCH<SUB>3</SUB>)<SUB>2</SUB>-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>], 11. In 5, the ether group is above the open face of the carbaborane cage, such conformation being shown to be electronically/sterically preferred by the results of EHMO calculations. In 11, the two ether groups are coordinated to a lithium atom and both are above the open face of the carbaborane cage. Chapter 3 details studies on late d block metal complexes with ether carbaborane ligands, and again emphasis is placed on their <SUP>11</SUP>B n.m.r. properties and their solid state structures. The crystal and molecular structures of 1,2-(CH<SUB>2</SUB>OCH<SUB>3</SUB>)<SUB>2</SUB>-30(<i>p</i>-<i>cym</i>)-3,1,2-<i>closo</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>9</SUB>, 12, 1-(CH<SUB>2</SUB>OCH<SUB>3</SUB>)-3,3-(Me<SUB>2</SUB>PhP)<SUB>2</SUB>-3,1,2-<i>pseudocloso</i>-PtC<SUB>2</SUB>B<SUB>9</SUB>H<SUB>10</SUB>, 16, and α- and β-7,8-(CH<SUB>2</SUB>OCH<SUB>3</SUB>)<SUB>2</SUB>-10-<i>endo</i>-(Ph<SUB>3</SUB>PHg)-7,8-<i>nido</i>-C<SUB>2</SUB>B<SUB>9</SUB>H<SUB>9</SUB>, 17α and 17α, are described. In 12, which contains a d<SUP>6</SUP>(Ru) metal centre, the ether oxygen atoms are orientated away from the metal atom. In 16, which contains a d<SUP>8</SUP>(Pt) metal centre, one of the two molecules in the asymmetric fraction of the unit cell has the ether oxygen atom weakly coordinated to the platinum atom. Additionally, the 'rotation' of the (Me<SUB>2</SUB>PhP)<SUB>2</SUB>Pt group over the C<SUB>2</SUB>B<SUB>3</SUB> face of the carbaborane cage is investigated using EHMO calculation, and found to be the result of the effect of the pendant ether group on the frontier MO's of the carbaborane. In both 17α and 17β, the mercury atom is coordinated by pendant ether groups; both in 17α, only one in 17β.

This thesis is concerned with the electrochemistry and spectroscopy of redox-active late transition metal complexes of the 2,2'-bipyridine ligand (bpy) and their reduction products. Complexes of general formula [Ph(4,4'-X<SUB>2</SUB>-bby)L<SUB>2</SUB>] (where L is a non redox-active ligand and X = NH<SUB>2</SUB>, OEt, Me, H, Ph, C1, CO<SUB>2</SUB>Me) undergo two one-electron reductions as revealed by cyclic voltammetry. The absorption spectra of the one-electron reduction products reveal the first of these reductions to be localised on the bpy ligand giving rise to radical anion ligand complexes of Pt(II). Epr spectra of the reduced, seventeen-electron species indicate a significant (<I>ca. </I>10%) admixture of metal 5d orbitals in the SOMO, in good agreement with EHMO calculations. Both the E<SUB>1/2 </SUB>value of the first reduction process and the MLCT ν<SUB>max</SUB> value vary linearly with the Hammett parameter of the substituent X. The second reduction electron spin-pairs with the first in the same π* orbital. The LUMO of [Pd(4,4'-X<SUB>2</SUB>-bpy)C1<SUB>2</SUB>] is Pd 4d based and these complexes undergo irreversible two-electron reductions. Complexes of the 4,4'-(NO<SUB>2</SUB>)<SUB>2</SUB>-bpy ligand undergo up to four one-electron reductions. Epr spectroscopy of the di-reduction products of [M(4,4'-(NO<SUB>2</SUB>)<SUB>2</SUB>-bpy)L<SUB>2</SUB>] (M = Pd, Pt, L = C1; M = Rh, L<SUB>2</SUB> = 1,5-cod) shows that spin-triplet species are formed on di-reduction and consequently that the LUMO-SLUMO gap is smaller than the spin-pairing energy for these complexes. The redox-active orbitals are highly localised on the nitro-groups. EHMO calculations are in good agreement. [Pt)bpy)<SUB>2</SUB>]<SUP>2+</SUP> undergoes a redox-induced dimerisation reaction at room temperature. Low-temperature cyclic voltammetry reveals the redox-active orbital to be bpy-based. The single-crystal structures of [Pt(4,4'-(NO<SUB>2</SUB>)<SUB>2</SUB>-bpy)C1<SUB>2</SUB>] and [Au(bpy)C1<SUB>2</SUB>]BF<SUB>4</SUB> are reported.

No description available.

No description available.