Two compounds previously described as trichloro-bis(triphenylphosphine)rhenium(III) have been shown to be trichlorobis(triphenylphosphine oxide)rhenium(III) and oxotrichlorobis(triphenylphosphine)rhenium(V). Other phosphine complexes of Re(III) and Re(II) prepared in a similar manner to the latter have been shown to be com-pounds of Re(V). A new arsine complex of Re(V) and other arsine and arsine oxide complexes of rhenium(III) have been prepared. A triphenylphosphine complex of Re(II) has been prepared. Previously reported cyanide complexes of Re(VI) and Re(V) have been confirmed, although the purification procedure described for the latter causes hydrolysis of the compound. The supposed purple hydroxocyanide complex of Re(VII) has been shown to be the oxohydroxocyanide complex of_Re(V),- as have previously reported purple salts of the dioxotetracyanorhenate(V) have also been shown to be salts of this anion. The first transition metal-nitridocyanide complex has been prepared. A new method of preparing potassium dioxotetracyanorhenate(V) is described. It has been shown that the diagnostic region for M=0 infra-red stretching frequencies must be extended from 900 cm.-1 down to at least 780 cm.-1 where a linear 0=M=0 group exists in an octahedral complex. Stable phases Re205 and Re308 have been prepared by the oxidation of rhenium dioxide hydrate. The former is a mixture of Re03 and an unidentified oxide. The latter does not contain any Re03. Mixed phosphine 2:4-propanedione complexes of rhenium(V) and rhenium(III) have been prepared.

Two cryostate,respectively for measurements of electrical resistivity between 1'4 and 300°K, and magneto-resistance at fixed temperatures, are described. Detailed examination of the resistivities of Pd and a Pd-RhAg alloy isoelectronic with pure Pd, was made; no indication of anomalies in the temperature region of the suspected antiferromagnetic transition, postulated to explain the maximum in the susceptibility, were found. This result, it is pointed out, is not inconsistent with Lidiard's collective electron theory of antiferromagnetism and indicates furthermore that spin-disorder effects are of negligible significance. In of - Mn, the resistivity exhibited a marked change in slope in the neighbourhood of its antiferromagnetic transition point. Corresponding behaviour in the Mn alloys indicated that the effect of adding Fe was to increase, and of Cr to lower, the Ndel temperature in Mn 5% Cr antiferromagnetism appeared to have been completely supressed. The results are considered in terms of Overhauser's spin density wave mechanism of antiferromagnetism; and the functional dependences of the resistivities on temperature are analysed employing an elementary phenomenological theory. The resistivity of Cu3Au-Mn showed features qualitatively similar to those observed in Cu-Mn alloys and, normally associated with some type of co-operative exchange between Mn atoms; neither these interactions nor the configuration of the Mn atoms appeared to be significantly affected by the change in the configuration of the conduction electrons with ordering of the matrix. Measurements also have been made of the low-field transverse and longitudinal magneto-resistance at 4.2, 77 and 293°K in alloys of Ag with Pd, Cd and Au. The considerable variations in the magneto-resistance coefficients with alloying and with temperature are attributed to the combined effects of deformation of the Fermi surface and differences in anisotropy of the relaxation time for different scattering mechanisms. The data for AgCd are shown to be to some extent in qualitative agreement with the hypothesis, put forward by Cohen and Heine, that the band structure becomes less distorted with additions of Cd, whereas the appreciable increase in the coefficients with additions of Pd is ascribed to increasing anisotropy of the Fermi surface.

A number of different methods have been used in the preparation of substituted ammonium polyphosphates. Products produced in different ways always had the same unit cells, but the degree of crystallinity and texture of the products varied with the method of preparation. The most crystalline products were obtained by ion exchange of inorganic polyphosphates. Sorption was studied with amyl-, heptyl-, nonyl-, dodecyl- and cetyltrimethyl- ammonium and anilinium polyphosphates. A number of different sorbates were used. Ethanol and amyl alcohol were found to react with primary alkyl ammonium polyphosphates, the effect becoming considerable in the case of the system amyl alcohol/amyl ammonium polyphosphate. Anilinium polyphosphate was also found to react with ethanol. Such reaction tended to alter the sorptive capacity of the polyphosphates. In addition, the sorption of water, nitromethane and a number of hydrocarbons was studied. Normally, reaction did not occur with these sorbates. Thermodynanmic evidence was obtained for some of these systems and it was attempted to interpret such evidence qualitatively in terms of models. Cetyl trimethylammonium polyphosphate differed from the other sorbents, both in structure and its tendency to dissolve in the sorbates. Equilibrium was attained very slowly with this sorbent. Information has been obtained by X-ray measurements about changes in the unit cells of certain polyphosphates in equilibrium with varying pressures of sorbates. This has been discussed in terms of the extent of uptake of such vapours, as determined by sorption measurements.

In this thesis, mechanistic insights into lignin depolymerisation and more specifically, the hydrolysis of the abundant β-O-4 ether linkage was gained. This was accomplished by exploring the reactivity of different lignin model compounds in acidic ionic liquids. Reported herein are investigations into the reactivity of 2-phenoxyethanol in 1-butylimidazolium hydrogensulfate with varying amounts of sulfuric acid. Ring sulfonation was observed with the ether bond remaining intact. A similar study was then conducted using 1-ethyl-3-methylimidazolium bromide in the presence of hydrobromic acid. A Hammett plot confirmed the mechanism of ether cleavage proceeding via an A2 mechanism, yielding the phenolic product and 2-bromoethanol. The preparation of an array of lignin model compounds bearing the full β-O-4 linkage was also accomplished. Mechanistic studies indicated that the rate determining step involves substrate dehydration followed by hydrolysis in ionic liquid media. This is analogous to the mechanism reported in acidic aqueous media, however was found to proceed 25 times faster. The reactivity of guaiacolglycerol-β-guaiacol ether was compared between hydrogensulfate ionic liquids. An Eyring investigation showed a consistent mechanism in all ionic liquids with full isokinetic compensation observed between the ΔH‡ and ΔS‡ components. The differences in the absolute values of ΔH‡ and ΔS‡ were deduced to be due to the interaction of the hydrogensulfate anion with the protonated substrate, influenced primarily by the associative forces between the cation and anion, namely hydrogen bonding and sterics. A final study explored the oxidative depolymerisation of ionosolv lignin using a polyoxometalate catalyst in 1-butylimidazolium hydrogensulfate. Vanillin and syringaldehyde were identified to be the products of highest abundance and it was observed that shorter pretreatment times led to higher aldehyde yields. Preliminary studies identified that a 5 wt % POM loading with hydrogen peroxide at 100 ° C provided the optimal conditions to yield the aldehydes.

No description available.

The opening Chapters summarise the previous work on electrical conductivity, density and ultra-violet spectroscopy in fused salt systems, and on the melting process for ionic substances. The aim of the present work is defined in relation to this previous knowledge. The electrical conductivities and densities of fused KNO3 - Ba(NO3)2 mixtures were measured. The conductivity of KNO3 is depressed when Ba(NO3)2 is added, so the divalent ions restrict ionic migration. Consistently with this interpretation, the equivalent volumes of the molten mixtures decreased with rising barium concentration, and the fraction of the volume actually occupied by the ions also decreased. These results contrast sharply with correspond-ing results for ionic crystals, which points to limitations in the applicability of the 'quasi-crystalline' model to ionic melts. The near ultra-violet absorption spectra of the alkali metal nitrates, silver, thallous and ammonium nitrates, nitric acid and iso-propyl nitrate were measured at temperatures up to and beyond their melting-points. The weak band at 33 kcm-1 is due to an internal transition (n -4.1r* ) in the nitrate ion; its maximum frequency, E(2), depends on the identity of the cation, on the temperature and on crystal structure. 7,(2) is determined largely by the first shell of cations around each nitrate ion; for a given salt an increase in E(2) corresponds to a decrease in the nearest cation - oxygen distance, and vice versa. This leads to the important conclusion that the nearest-neighbour cation - oxygen separation decreases on fusion, in spite of the macroscopic increase in volume. Similar conclusions were reached about the melting process in sodium and potassium nitrites. The temperature dependence of the % transmission of a thin film of salt at fixed frequency provided a means for determining transition temperatures and for studying hysteresis in phase transformations.

The kinetics of the reactions of some anionic and cationic halogenoplatinate(IV) complexes with halide ions have been studied by spectrophotometric methods; the majority of the reactions were sufficiently fast to be followed using the stopped-flow technique. The reactions of trans- Pt(CN)4 X22- and trans- Pt0x2X22- (X = Cl, Br) with iodide are first order in both iodide and complex concentration and the mechanism probably involves a rate determining reduction of the Pt(IV) complex to Pt(II) followed by a fast reoxidation. The rates of the reactions appear to be related, in the majority of cases, to the thermodynamic ease of reduction, this indicates that both Pt-X bond breaking and X-I bond making play an important part in determining the rates of reaction. Several equilibrium constants for reduction of these complexes by iodide, bromide and chloride, as well as estimates of values for the replacement of chloride and bromide by iodide in trans- Pt(CN)4X22-, have been obtained.

Infrared (IR) spectra of complexes consisting of an alkali halide salt (MX) molecule and one or more protic solvent molecules have been recorded for the first time in this thesis. NaCl and LiI are the principal salts investigated and have been combined with the solvents water and methanol to form complexes of type MX(solvent)n (n = 1-7) in liquid helium nanodroplets. IR spectra were recorded using a depletion technique. For small complexes (n = 1 – 3) the spectra are consistent with formation of contact ion-pair structures in which each solvent molecule forms a single ionic hydrogen bond (IHB) to an intact M+X- ion-pair. For n ≥ 4, the IR spectra suggest that multiple isomers of MX(solvent)n are present in helium nanodroplets. Ab initio calculations were used to support the results by predicting possible structures and their corresponding IR spectra. A mass spectrometric study of a variety of alkali halide salts with a variety of protic and aprotic solvents in helium nanodroplets was also performed. The aim here was to survey the mass spectrometric behaviour of species within the helium nanodroplets in preparation for future IR spectroscopic studies. The salts chosen for this study were NaCl, NaBr, NaF, NaI, LiI, LiCl, CsI and KF, while the solvents chosen were water, methanol, acetone and acetonitrile, i.e. two protic and two aprotic solvents. The ions observed in the mass spectra have been described and assigned to be derived from the neutral species in helium nanodroplets environment.

This thesis presents a body of original research describing the synthesis, characterisation and biological properties of novel arsonium- and phosphonium- alkylthiosulfate zwitterions and thioacetate salts and gold nanoparticles functionalized with triphenylarsoniumpropylthiolate ligands. Chapter 1 presents a systematic literature review of the preparation of functionalized gold nanoparticles, their biomedical properties, the biological applications of phosphonium and arsonium ions and phosphonium-functionalized nanomaterials. Details of the analytical methods employed to characterize all the compounds produced in this study are outlined in chapter 2. Chapter 3 reports the synthesis of the triphenylarsoniopropylthiosulfate zwitterion and ω- thioacetylpropyl(triphenyl)arsonium bromide salt. Both compounds have been characterized spectroscopically and by single crystal X-ray diffraction. The thiosulfate group of the triphenylarsoniopropylthiosulfate zwitterion and the thioacetate group of the ω- thioacetylpropyl(triphenyl)arsonium salt undergo reductive cleavage, forming the corresponding triphenylarsoniumpropylthiolate ions that attach to the surface of gold in a modification of the established Brust-Schiffrin method for preparing gold nanoparticles. TEM studies show the triphenylarsonium-functionalized gold nanoparticles to be spherical with diameters of c.a. 3nm. The presence of the triphenylarsonium groups has been confirmed by Raman and XPS spectroscopy and mass spectrometry. It also describes the synthesis, characterisation and biological properties of a family of phosphoniopropylthiosulfate zwitterions and ω-thioacetylpropyl(triaryl)phosphonium salts derived from tri(4-methoxyphenyl)phosphine, tri(2,6-dimethoxyphenyl)phosphine and tri(2,4,6-trimethoxyphenyl)phosphine. The IC50 values of the triphenylarsoniopropylthiosulfate zwitterion, ω-thioacetylpropyl- (triphenyl)arsonium bromide salt, triphenylarsonium-functionalized gold nanoparticles and family of phosphoniopropylthiosulfate zwitterions and ω- thioacetylpropyl(triaryl)phosphonium salts derived from tri(4-methoxyphenyl)phosphine, tri(2,6-dimethoxyphenyl)phosphine and tri(2,4,6-trimethoxyphenyl)phosphine have been determined against PC3 prostate cancer cells using MTT and CellTiter-Glo assays and are reported in Chapter 4. The uptake of the triphenylarsonium-functionalized gold nanoparticles by PC3 and Human Fibroblast cells has also been determined by ICP-OES spectroscopy.

Complexes of several well-known types of Uganda have been prepared with manganese(11) halides and thiocyanate in order to elucidate their complexing properties and to compare these with those toward other first-row transition metals. During studies to determine the stereochemistry of the complexes prepared, several new methods for these types of compound were investigated. Two proved of particular usefulness for manganese; Raman spectroscopy, (since most of the complexes are white) and electron-spin resonance spectroscopy, The latter technique has been employed in two ways. Qualitatively, the stereochemistry of new complexes was determined by comparison of their spectra with those of complexes of known stereochemistry, and quantitatively, comparison of the observed spectra with calculated transitions enabled the zero. field splitting parameters, D and E-to be deduced. The parameter, λ, defined as the ratio, E/D, has been shown to be closely related to the symmetry of the complex. In those with axial symmetry, λ≈O; in those with tetrahedral or distorted octahedral geometry, λ≈1/3. In several series of complexes, D is found to increase with anion from thiocyanate to chloride to iodide.