Formaldehyde is an important industrial chemical due to its unique properties, coupled with its low cost and the basic availability of the raw materials from which it is produced. It is generated principally by the catalytic oxidation of methanol using a heated stationary catalyst at approximately atmospheric pressure. Formaldehyde is used in the manufacture of a wide variety of commercial products, the most significant of which in New Zealand, are the urea-formaldehyde resins. Such resins are used in the production of reconstituted wood products such as: particleboard; medium density fibreboard; plywood; laminated and finger jointed wood products; and in the modification of textiles and papers. Insulating building foams have also been formulated using urea-formaldehyde resins. Formaldehyde release from products containing urea-formaldehyde adhesives has been well documented in the literature over recent years. It has been shown that in some instances the levels of airborne formaldehyde inside dwellings and commercial premises may exceed various industrial threshold limit values for an eight hour working day. In New Zealand the current industrial permissible time weighted average value for formaldehyde in air is set at a maximum level of 2 ppm (2.4 mg of formaldehyde per metre3 of air). Natural levels of formaldehyde in air do exist and have been measured as being in the vicinity of 0.12 to 0.39 parts per billion. In terms of being a health hazard, formaldehyde was found to be a primary irritant of the respiratory airways and a skin sensitizer in some individuals. Some suggestion has been made that formaldehyde can also be carcinogenic. This suggestion should be treated with caution as it derives from preliminary experiments on rats and mice exposed to very high formaldehyde levels. Over the years a variety of test methods have been applied to the measurement of formaldehyde which is released from formaldehyde-bearing materials. A dynamic testing method, in the form of a wind-tunnel was adopted in this study for measuring the emission rate of formaldehyde directly from the surfaces of urea-formaldehyde bonded particleboard. Emissions were quantified in terms of the weight of formaldehyde emitted in mg from one square metre of panel surface over one hour, under the prevailing climatic conditions. It was observed that formaldehyde emissions were as great as about 12 mg h-1 m-2 from panels tested soon after manufacture. After five years of storage of the particleboard panels in ventilated conditions, the formaldehyde emission rates were measured as being between 0.1 and 1.1 mg h-1 m-2. It was apparent that formaldehyde emissions from particleboard bonded with a urea-formaldehyde resin with a urea to formaldehyde molar ratio of 1 to 1.5, reached a basal level approximately 12 months from the time of manufacture. The formaldehyde emitted over the initial 12 month period was equated to the formaldehyde which was originally present dissolved in the resin solution and the formaldehyde which was cleaved from the urea-formaldehyde polymer network during high temperature pressing. Formaldehyde lost from the particleboard after the initial 12 month storage phase was probably due to hydrolysis of the resin under ambient conditions. The latter was termed "evaporable" formaldehyde as opposed to "free" formaldehyde which was emitted in the first 12 month period. The fluctuations in the basal emission rates of formaldehyde from particleboard were attributed to changes in the microclimate associated with the particleboard. Particleboard panels with a higher density surface layer of wood tended to have higher formaldehyde emission rates in the early period of storage compared with particleboard having a lower density of wood in the surface layer. Emissions of formaldehyde from the edges of freshly sawn particleboard tended to be as much as 30 to 60 times greater than emissions from the faces of the original panels. After extended storage, emissions from the edges of particleboard tended to approximate the levels of emissions from the faces of particleboard. It was demonstrated that the presence of an air boundary layer adjacent to the particleboard surface has a significant effect on the formaldehyde emission rate from the panel surface. Below air speeds of 5 cm s-1 over the panel surface, it appeared that the rate of diffusion of formaldehyde through the air boundary layer controlled the rate of diffusion of formaldehyde from the particleboard surface into the bulk air. At air velocities in excess of 5 am s-1 the effect of the air boundary layer diminished. It was estimated that within enclosed spaces, such as houses with a relatively low air-turnover rate, the diffusive resistance of air boundary layers to formaldehyde emissions from particleboard surfaces could be significant in lowering the formaldehyde levels inside the house. The use of paints, paint-coated wallpaper and polymer-coated wallpaper to cover particleboard surfaces tended to reduce the emission rate of formaldehyde to below the detection threshold of the method of measurement (0.01 mg h-1 m-2). Some building materials other than urea-formaldehyde bonded particleboard were shown to emit measureable quantities of formaldehyde. These materials were of cellulosic-origin and emitted as much as 0.3 mg of formaldehyde h-1 m-2. The latter were known to not contain urea-fonnal6ehyde bonding agents. The levels of formaldehyde inside a showhome containing urea-formaldehyde bonded particleboard as wall and floor cladding were measured as ranging from 1.2 to 7.2 mg m-3, but these air-borne concentrations of formaldehyde decreased to between 0.7 and 1.3 mg m-3. after an interval of three months. A mathematical model was derived for the prediction of the maximum expected steady state levels of formaldehyde inside dwellings containing formaldehyde-emitting materials. The model took into account such parameters as: the emission rate of formaldehyde from the emitting surface; the surface area of the exposed emitting material; and the volumetric air flow rate through the dwelling. The model in general tended to indicate higher formaldehyde levels when tested using the parameters derived from measurements taken in the showhome. This model could conceivably find use in the design of buildings in order to minimize the levels of formaldehyde in the indoor environment. The lack of sufficient information in the literature relating to the mass transfer of formaldehyde through polymers prompted the investigation into the permeability characteristics of polymeric materials to formaldehyde. The steady state transmission rates of formaldehyde through free polymer films, such as plastic films, free paint and free polyurethane varnish coatings, were measured using a diffusion cell operated at atmospheric pressure. The mass diffusion principle associated with this permeation testing device best paralleled the real-life situation where either polymer films (plastic films) or polymer coatings (paint or varnish coatings) may be in contact with formaldehyde and water vapour, at atmospheric pressure. As a source of penetrant in these studies a dilute aqueous solution of formaldehyde was used to yield molecular formaldehyde. It was calculated that an aqueous solution containing 69 mg L-1 of formaldehyde gave rise to a concentration in air of formaldehyde, above the solution, of 1 mg m-3 at 30°C. A solution with such a concentration of dissolved formaldehyde was chosen arbitrarily for permeation studies. Levels of air-borne formaldehyde inside enclosed airspaces such as in houses lined with urea-formaldehyde bonded particleboard, with a low air turn-over, could reasonably be expected to be in the region of 0.1 to 100 mg m-3. The use of carbon-14 formaldehyde was favoured in this research over the use of carbon-12 formaldehyde. This gave rise to the possibility of permeability isotope effects. Based on the information presented in this thesis and on the experimental variability in test results, it appeared that the effects of a permeability isotope effect were negligible in comparison. The transmission rates of formaldehyde through the following types of polymer films were measured: low density polyethylene; high density polyethylene; high density-low density polyethylene blended polymer; polypropylene; poly(ethy1ene terephthalate); poly(viny1idene dichloride)-coated Poly(ethy1ene terephthalate); "Paraform", a multi-layered food packaging polymer film based on cellophane; Poly(ethylene vinyl acetate), a multi-layered food packaging polymer film; plasticised poly(vinyl chloride); polystyrene; nylon-6; and cellophane. At 30°C transmission rates of formaldehyde ranged from 1.2 x 10-7 μg cm-1 s-1 for cellophane to 1.2 x 10-l2 μg cm-1 s-1 for poly (ethylene vinyl acetate) polymer films, respectively. There was some indication that the transmission rate of formaldehyde through low density polyethylene decreased with increasing film thickness. It also appeared that an increase in the water contents of nylon-6 and cellophane films lead to an increase in the transmission rate of formaldehyde. With the exception of the poly(ethylene terephthalate)-types of polymer films and the polystyrene film, all other polymer film types exhibited typical Fickian behaviour, in that the permeation of formaldehyde through each polymer film was steady state. The permeation of formaldehyde through poly (ethylene terephtha1ate)-type films and polystyrene film appeared to be anomalous in that the mass transfer process did not appear to show Fickian-type behaviour. The transmission rates of formaldehyde through free alkyd-type paint films, free vinyl-based paint films and through free polyurethane varnish films, were measured at 30°C. The permeation of formaldehyde through free alkyd-type paint films and free polyurethane varnish films typified Fickian behaviour, in that after a short time-lag the steady state permeation of formaldehyde occurred. The transmission rates of formaldehyde through the free alkyd-types of paint film ranged from 1.8 x 10-9 μg cm-1s-1 to 3 2 x l0-9 μg cm-1 s-1 whereas transmission rates of formaldehyde through free polyurethane varnish films ranged from 4.1 x 10-10 μg cm-1 s-1 to 2.4 x 10-8 μg cm-1 s-1. It appeared that the "two-pack" or "catalytic-curing" type of polyurethane varnish film had a lower permeability to formaldehyde compared with either "one-pack" ("air-curing") or "one-pack" ("moisture-curing") varieties of polyurethane varnish. By contrast the transmission rates of formaldehyde through the vinyl-based types of paint films tended to range from 3.7 x 10-7 μg cm-1 s-1 to 6.2 x10-7 μg cm-1 s-1. A study of the temperature dependency of the permeation of formaldehyde through the following polymer film types was made: low density polyethylene; plasticised poly(vinyl chloride); polystyrene; polypropylene; high density polyethylene; cellophane; and nylon-6. The transmission rates of formaldehyde through each of these polymer film types increased with increasing temperature, over the temperature range of 30°C to 50°C, thus typifying Arrhenius behaviour. The energies of activation for the permeation of formaldehyde were calculated as ranging from 16 1 kcal mol-1 (67.4 kJ mol-1) for plasticised poly (vinyl chloride) to 33.1 kcal mol-1 (139 kJ mol-1 for cellophane, respectively. These activation energies were in general higher than the energies of activation for the permeation of other penetrants of similar molecular weight, through the same polymer types. The observed energies of activation for the permeation of formaldehyde through polymers were indicative of a strong interaction between formaldehyde and the various polymers. Desorption studies of formaldehyde from polymer films tested after permeability measurement, indicated that formaldehyde was irreversibly sorbed either onto or into the following polymer film types: low density polyethylene; poly(ethy1ene vinyl acetate); polypropylene; polystyrene; and plasticised poly(vinyl chloride). Formaldehyde was found to desorb from nylon-6 and cellophane polymer film types, indicating a different type of interaction between formaldehyde and these two polymer film types. The autoradiography of polymer films and free polymer coatings following permeability testing showed that the pattern of sorbed carbon-14 formaldehyde exhibited by each polymer film type or free polymer coating type, differed according to the type of polymer. Clustering of sorbed carbon-14 formaldehyde in polymer films containing polyethylene polymers may have been indicative of the formation of formaldehyde-formaldehyde polymers or perhaps could have been due to preferred pathways or sites for the diffusion of formaldehyde through the polymer film. The following types of polymer film tended to show a uniform sorption pattern of formaldehyde: nylon-6; cellophane; "Paraform"; free alkyd paint films; free vinyl-based paint films; and free polyurethane varnish films. The uniform appearance of the sorption pattern of carbon-14 formaldehyde may have been indicative of a higher solubility coefficient of permeation for formaldehyde in the latter polymer types. On the other hand, insufficient carbon-14 formaldehyde was sorbed by the poly(ethylene terephthalatel-type and polystyrene films in order to obtain autoradiographs. Both the poly(ethylene terephthalate)-types of films and the polystyrene film had a relatively low permeability to formaldehyde and appeared to also have a low solubilizing effect on formaldehyde. The data presented in this thesis are discussed in relation to the practical problem that initiated the study. Sufficient detailed information has been collected to enable informed decisions to be taken over the choice of formaldehyde-emitting materials used in the building and the food packaging industries.

The fully regio-controlled synthesis of C1a-C12a mono-seco colchicine 133, as well as a number of structurally interesting analogues, has been achieved. The key feature employed in our approach to troponoid compounds of this type has been the incorporation of synthetic equivalents for α-tropolone anions 84 and 87 via dehydrobrominative ring expansion of C7-substituted7-bromobicyclo[4.1.0]heptan-2,3- and -3,4-diones respectively. The hydroxyl functionality present in tropolone 143 has been found to be a suitable progenitor for the C7-acetamido group in mono-seco colchicine 133. Studies directed towards the enantio-controlled introduction of the C7-acetamide moiety via asymmetric reduction of the prochiral ketone 152 are discussed. Various strategies to effect B-ring closure in mono-seco colchicine 133 and its congeners are presented. The novel preparation and dehydrogenative dimerisation of desacetamido mono-seco colchicine 174 is reported. An efficient synthesis of the naturally occurring tropone nezukone (16) has been accomplished via the novel rearrangement of bicyclic methylene cyclopropane 209. Evidence for the intermediacy of heptafulvenes in this conversion is described.

A series of structures of light atom molecules is presented. The molecules, in the main, are physiologically active or potentially active. The molecules have been divided into five broad categories. Their structure and properties are discussed. Section 1 presents some organic natural products largely isolated during the chemotaxonomic investigation of coastal marine organisms from New Zealand and Australian waters including the first porphyrin isolated from a sponge. Also presented are the structures of an isostegane and an intermediate in the synthesis of potentially odoriferous compounds. Section 2 presents compounds related to the drug amsacrine m-AMSA, of known chemotherapeutic use and other compounds produced in the study of chemotherapeutic agents, some as templates for elaboration into bis- and tris- intercalators. Section 3 presents anthraquinone derivatives related to the synthesis of compounds of known chemotherapeutic activity. One of these is a stable ozonide. Section 4 presents the study of 4, 4'-bipyridinium cations, compounds related to paraquat and exhibiting interesting electrical properties. Section 5 presents two compounds related to the study of colchicine, the most commonly used drug in the treatment of gout and a compound of other biological interest. One is an active analog the other is an intermediate in the regiocontrolled synthesis of colchicine itself.

Molecules containing transition metal-carbon multiple bonds have been recognised as active species in catalytic reactions and key intermediates in stoichiometric reactions. It is therefore important to gain an understanding of the reactivity of these functional groups. The metal-carbon double bond is introduced in Chapter 1 with a literature review and the following two chapters are concerned with the synthesis and properties of a new class of Group VIII metal carbene complexes containing the prototype carbene ligand, =CH2. The synthetic route to the first of these complexes involves a new low-valent osmium complex OsCl(NO) (PPh3)3. The synthesis of this complex from a reformulated complex containing the novel peroxycarbonyl ligand is discussed in Chapter 2, followed by simple reactions including the synthesis of a range of acetylene, allene and heteroallene π-adducts. The reactions establish that OsCl(NO)(PPh3)3 reacts as the osmium analogue of IrCl(CO)(PPh3)2. The methylene-ligand synthesis involves the addition of diazomethane to OsCl(NO)(PPh3)3 to give the structurally characterised Os(CH2)Cl(NO)(PPh3)2. The reaction has been extended to give the first isolable ruthenium and iridium methylene complexes. The reactions of these complexes establish the nucleophilicity of the double bond and two Lewis acid adducts, Os(CH2AuI)Cl(NO)(PPh3)2 and [Os(CH2S(O)O)Cl(NO)(PPh3)2]ClO4, have been structurally characterised. The reaction with CO and isocyanides to form ketene and ketenimine ligands illustrates a different mode of reaction that is interpreted in terms of the non-innocent participation of the nitrosyl ligand. The change from nucleophilicity to electrophilicity of the double bond with a reduction of metal electron density is illustrated by reactions of Os(CH2Cl)Cl2(NO)(pph3)2 which implicate [OS(CH2)Cl2(NO)(PPh3)2]+ as an intermediate. Os(CH2Cl)Cl2(NO)(PPh3)2 is formed by addition of Cl2 to Os(CH2)Cl(NO)(PPh3)2. In Chapter 4 a different type of metal-carbon double bond is discussed. The complexes contain the relatively uncommon dichlorocarbene ligand and the synthesis of the first such iridium complex, Ir(CCl2)Cl3(PPh3)2 is described. The utility of the dichlorocarbene ligand in the synthesis of a range of carbene ligands including monochlorocarbene complexes is illustrated. The most useful single reaction of the dichlorocarbene complexes is that forming a metal-carbon triple bond. A review of the literature concerning carbyne complexes is presented in Chapter 5 and the synthesis and reactions of a number of carbyne complexes is discussed in Chapter 6. Like the methylene complexes, the carbyne complexes such as Os(CPh)Cl(CO)(PPh3)2 contain nucleophilic metal-carbon bonds and Os(CHPh)Cl2(CO)(PPh3)2 resulting from HCl addition has been structurally characterised. However, just as the reactivity can be changed with the methylene complexes, the reduction of metal electron density in complexes such as [Os(CR)Cl2 (CNR')(PPh3)2]ClO4 (R = C6H4-4-NMe2, R' = C6H4-4-Me) makes the triple bond electrophilic. Two methods for synthesising these octahedral carbyne complexes are described. One, involving a reaction of complexes such as Os(CPh)Cl(CO)(PPh3)2 with oxygen and the formation of another peroxycarbonyl ligand, the other a reaction with iodine to give complexes such as Ru(CPh)ClI2(PPh3)2. Reactions with chlorine by contrast lead to a group of reactive chlorophenyl carbene complexes. Where appropriate, the reactivity of the complexes described is interpreted in terms of frontier-orbital and charge controlled reactions using the current models for the carbene and carbyne complexes.

The reactions and transformations of atmospheric primary particles have been studied using the surface analysis techniques of X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM) and Secondary Ion Mass Spectrometry (SIMS). Particles emitted from a steel mill were studied at their point of emission, during transport through the atmosphere and after deposition. The mill was located in a coastal region removed from other major industrial particle sources which made the identification of the mill particulate emissions possible in ambient samples. The mill utilizes indigenous titanomagnetite ironsand and coal as the raw materials. There is evidence of the surface enrichment of volatile trace elements such as Zn, S, Na, K and P from the raw materials in the particulate emissions. Particle samples were collected from sites within the mill which represented different stages in the iron-making process, including the rotary kilns, electric melting furnaces and the vanadium recovery plant. This established an inventory of particulate emissions. Mill sourced particles were then identified and studied in air samples collected downwind of the mill on silver-coated nucleopore filters. AES and SIMS depth profiling studies indicated the mill particles became surface enriched in sea salt components such as S, predominately as sulfate, Cl- and Na+ after atmospheric aging. This was attributed to their coagulation with the marine derived ambient aerosol. SIMS ion imaging and mass spectral analysis suggested a characteristic "fingerprint" of the mill emissions could be distinguished in the ambient aerosol up to 8 km downwind of the mill. An experimental rig was constructed to model the interaction between the mill particles and the natural marine aerosol. A bubble nebuliser was developed to produce an artificial sea salt aerosol which was reacted with a metal powder in the fluidised bed of the rig. The metal powder was then aged under controlled relative humidity (RH) conditions. It was shown that an iron powder, after reaction and aging at 75% RH, developed an aqueous surface layer which quickly led to electrochemical corrosion, dissolution and oxidation of the particle surface. Evidence of this corrosion of metal particles occurring in the environment was found in a SEM-EDX study of the mill particles deposited on pine needles downwind of the mill. It was argued that these reactions would increase the bio-availability of the particle components. A model which incorporated these observations was developed to describe the morphogenesis of atmospheric primary particles during aging in the New Zealand environment. XPS was used to study ambient aerosols deposited on both botanical and artificial passive sampling surfaces. Plant leaves were shown to be excellent collectors of particulate material and were suited to analysis by XPS. Site differences in the atmospheric aerosol load and composition were detected on vine leaves located on a hill side (high NaCl) and at a roadside (high sulfate and silicates) in a rural area. Zn and Fe species were detected by XPS on pine needles up to 2 km downwind of the steel mill.

This thesis deals with the nucleation, growth and defect structure of anodic oxide films formed on bismuth in aqueous electrolytes. The early stages in the formation of continuous anodic layers of bismuth oxide were studied using the technique of cyclic voltammetry. During this period, the oxide, Bi2O3, covered the surface by a process of simultaneous thickening and spreading of patches. The study of oxide nucleation classified the metal surface into two different areas with different kinetics of oxide nucleation. The ratio of the two areas varied according to the history and original preparation of the surface. Film nucleation was also studied by the galvanostatic step and potentiostatic step methods. The rate of spreading of the oxide patches over the surface was shown to be controlled by the magnitude of the surface area still uncovered. Film thickening was studied using both galvanostatic and cyclic voltammetric techniques. The high field growth law i = Ā exp (BĒ) where i is the current density and Ē the field in the oxide layer, was found with parameters Ā = (1 ± 0.5) x 10-5 A cm-2 B = (2.0 ± 0.5) x 10-6 cm V-1 This value of B gives an activation distance for high-field ion transport, a* = 0.2 nm, comparable to the radius of a lattice site. These parameters were determined for very thin films in strongly alkaline electrolyte (pH 13; thickness <30 nm). At greater film thickness, cracking of the film gave a porous layer on top of a continuous barrier layer, and the apparent value of the parameter B increased to 1.7 x 10-5 cm v-1. All previous work on the bismuth anodic film thickening process has been affected to some extent by cracking of the film. In this work, cracking of the film was confirmed by microscopic observation, including scanning electron microscopy. Dissolution of the film, giving breakdown of the oxide layer and pitting of the metal, was an important phenomenon. It became particularly significant for pH <8. The thickness attained by the anodic bismuth oxide layer was limited by this process to only 4 nm at pH 5, increasing to over 200 nm at pH 13. The cathodic reduction of the oxide proceeded from the outer surface inwards, and a rough, porous metal surface resulted. A model involving electron injection from the metal into the oxide, diffusion of electrons through the film and their reaction at the outer surface has been proposed. Microscopic observation confirmed the porous nature of the electro-reduced surface. The transient conductivity of the bismuth anodic film has been investigated, and the effects of standing at open-circuit in the electrolyte or of heating in air studied. The galvanostatic method was used. The observed effects could be adequately explained as being due to the presence ofanon-stoichiometric, n-type (excess metal) layer at the film-solution interface. Cyclic voltammetry was used to investigate the possibility of nucleation of anodic bismuth oxo-halides from solutions containing halide ions. Solutions containing fluoride, chloride, bromide or iodide at pH 4-9, phosphate and phosphate with added methanol at pH 8.5 were used. Consideration of thermodynamic stability would indicate the formation of new phases, but results showed that, in the comparatively short time scale of the experiments, kinetic factors resulted in the formation of anodic Bi2O3, except when the solution contained iodide at low pH, when the oxo-iodide, BiOI, was probably formed. Room lighting had no effect on the cyclic voltammetric or galvanostatic measurements. The transient response of anodic films on bismuth to an intense flash of white light was studied. In the case of a thick anodic oxide film (240 nm), the results were interpreted in terms of photo-excitation of the film, producing electron-hole pairs which were separated by the applied field. The recombination process was best described as rate-limiting thermal excitation of trapped electrons. The lifetime of an electron in the conduction band of anodic Bi2O3 was determined: τc = 23 ms. The photo-response of a very thin anodic oxide film (4 nm) involved internal photo-emission of electrons from the metal into the oxide. Formation of a positive space charge by the injection of extra cations from the metal into the film followed. The transient photo-potential (galvanostatic experiments) or photo-current (potentiostatic experiments) showed the decay of both excess electronic and ionic space charges. The density of electron traps in the anodic oxide film was determined as NT > 3 x 1018 cm-3. When the anodic film was formed in a solution containing bromide or iodide at pH 5, an inversion of the sign of the primary photo-effect from that observed in the absence of additives (4 nm thick film) was seen, and interpreted in terms of the photo-excitation of halide ions incorporated in the film. The lifetime of a conduction electron in anodic BiOI was determined as 1.5 ± 0.2 ms, much less than in anodic Bi2O3 (23 ms). In all the studies of the photo-effect, Gauss' theorem was used to relate the observed photo-potential (galvanostatic experiments) to the photo-induced charge separation. An approximate value of the conduction electron mobility in anodic Bi2O3 was thus obtained: μ ≃ 5 x 10-8 cm2 V-1 s-1. Parameters for the evolution of hydrogen on the bare bismuth metal surface, were obtained: b = 0.11 V, log10(i0/Acm-2) = -10.3 and (∂(log10i0)/∂(PH))η = 0 where η = E – 60 pH mV.

The infra red, Raman and nuclear quadrupole resonance (n.q.r) spectra of several complexes of copper(I), silver(I) and gold(I) are reported. These are interpreted in terms of the structures of the complexes and the various possible bonding schemes for these d10 transition elements. To interpret the n.q.r. spectra the contributions to the field gradient at the copper nucleus of the various orbitals in the copper atoms are calculated and the Townes and Dailey approximations are revaluated. From this the s-d mixing theory of Orgel is chosen as the most satisfactory description of the bonding in these complexes. This theory is extended to cover several other geometries besides the D∞h geometry for which it was originally derived.

This thesis describes the single crystal x-ray analyses of six novel organometallic osmium complexes and three complexes of the tridentate dentate ligand 1,6-bis(diphenylphosphino)-trans-hex-3-ene with the transition metals iridium, rhodium and ruthenium. The complexes of carbon monosulphide and carbon monotelluride with osmium, OsCl2(CO)(CS)(PPh3)2 and OsCl2(CO)(CTe)(PPh3)2, exhibit linear thio- and telluro-coordination similar to that of the carbonyl. The -CS and -CTe ligands exert strong trans-bond weakening influences. In the dihapto-thioacyl complex of osmium, Os(η1-o2CCF3)[C(S)-(p-tolyl)](CO)(PPh3)2, the bidentate thioacyl is coordinated to the osmium through the carbon and sulphur atoms. This bonding involves a considerable degree of π-interaction between the C, S and Os atoms, concomitant with a lengthening of the C-S bond. The dichlorocarbene complex, OsCl2(CO)(CCl2)(PPh3)2 is disordered in the crystalline state. Consequently, while the presence of the dichlorocarbene is verified, no unambiguous conclusions can be drawn from the associated geometry. In the carbyne complex of osmium, Os(C-p-tolyl)Cl(CO)(PPh3)2, the osmium is in a trigonal bipyramidal environment with an approximately linear arrangement of the Os-C-R group. The Os-Ccarbyne bond is short (corresponding to a bond order of ca. 3), confirming the formation of the C-p-tolyl group as a carbyne. The formaldehyde ligand in the osmium complex, Os(η2-CH2O)(CO)2(PPh3)2, is bonded to the osmium centre via both the carbon and oxygen atoms. The C-O bond of the formaldehyde lengthens considerably upon coordination, resulting in a bond order apparently less than 1. Also present in the crystal structure are molecules of water which are hydrogen bonded into pairs (O…O separation 2.56 Å). The (H2O)2 units do not hydrogen bond to any other atoms, but rather occupy hydrophobic interstices in the structure. The three complexes of 1,6-bis(diphenylphosphino)-trans-hex-3-ene, (BDPH), IrIIICl3(BDPH), RhIIICl3(BDPH), and RuIICl2(CO)(BDPH) are isomorphous. The ruthenium complex is, however, disordered in the crystalline state. In each of the three structures the olefin of the BDPH moiety is only weakly bound to the metal, leaving the C-C double bond virtually unchanged from that of the free ligand. The olefin exerts a stronger trans-bond weakening influence than do the chlorine ligands in these complexes.

This thesis is concerned with a study of the oxidation of ring-A aromatic steroids using either chromium trioxide-aqueous sulphuric acid-acetone or chromium trioxide-aqueous acetic acid mixtures. It was found that chromic acid oxidation of ring-A aromatic steroids substituted with a strong electron-donating group, gives rise to products with the site of oxidation being predominantly that para to the activating group. Thus C-3 methoxy ring-A aromatic steroids give the corresponding 9b-hydroxy-11-oxo and 9-oxo-9,11-seco-11-oic acid derivatives as the major products and the 6-oxo derivative as a minor oxidation product. However, a ketol was not formed if a C-3 methoxy ring-A aromatic steroid also contained a substituent at C-1. The C-1-methoxy-4-methyl ring-A aromatic steroids give the 4-carboxy derivative as the major product and again the 6-oxo compound as a minor neutral product. The acetoxy and methyl substituted ring-A aromatic steroids, however, all give rise to the 6-oxo derivatives as the major products. The usual oxidation product of a ring-A aromatic steroid is therefore the 6-oxo product unless it is substituted with a methoxy group in a position which will stabilise an electron deficiency at a site other than C-6. Oxidation will then occur predominantly at the stabilised site unless it is sterically blocked.

The modified reactivity observed when a substituted arene is complexed to a cycIopentadienylruthenium moiety has been exploited to prepare a range of synthetically interesting target molecules. Activation of nitrogen- and halogen- substituted arenes has been achieved by compIexation to the cyclopentadienylruthenium moiety. Double nucleophilic substitution reactions between substituted (7 6- 1,2-dichlorw benzene)RuCp+ salts and substituted 1,2-benzenediols were carried out under mild conditions to prepare substituted (q6-dibenzodioxin)ruthenium complexes. Both mono- and di-substituted dibenzodioxin complexes were prepared. The dibenzodioxin ligands were subsequently liberated by photolysis. The complexation of a range of substituted benzimidazoles to the cyclopentadienylruthenium moiety has been studied. Several complexes were isolated and structures proposed. The metal moiety has been used to influence the stereoselection achieved in the reduction of carbonyl substituted arenes. A number of keto-arene complexes were prepared and reduced with sodium borohydride. The resulting alcohol complexes were characterised and the observed diastereoselectivity rationalised. Yanovsky-like adducts were prepared by nucleophilic addition to the cationic ruthenium salts to produce neutral (n5-cyclohexadienyl)ruthenuim complexes. A comparison between lithium, silicon and tin enolates was undertaken.