This thesis presents the results of the synthesis of metal complexes of sulfa drugs (sulfadiazine, sulfamerazine, sulfamethazine, sulfathiazole and sulfadimethoxine) with secondary ligands, which were subjected to X-ray crystallographic studies. The aim of this work was to synthesise metal complexes of sulfa drugs with secondary nitrogen donor ligands e.g. ammonia, pyridine (py), ethylenediamine (en), diethylenetriamine (dien), 2,2'- bipyridine, 1,10-phenanthroline, 4,4'-dimethyl-2,2'-bipyridine, A(3-aminopropyl)-bis- (ethylenediamine) (apen) and oxygen donor ligands such as, water and dimethylformamide (DMF) and to investigate the different modes of coordination of the sulfa drugs molecules to the metal ions in the presence of nitrogen/oxygen donor ligands. Chapter 1, details an introduction into the fundamental concepts, procedures and equipment involved in data collection, solution and refinement of single crystal structures. In Chapter 2, a review of the literature on the metal complexes of sulfa drugs along with the main aims of this work is presented. In Chapter 3, the general experimental procedure and synthetic methods have been described for the metal complexes of sulfa drugs whose results and discussion are described in chapter 4. In chapter 4, the crystal structure of sulfadiazine, a new polymorph of sulfamerazine and the syntheses of the metal complexes of sulfadiazine, sulfamerazine and sulfamethazine, their analytical and spectral data along with the X-ray structure determination of the complexes are presented. The complexes studied in this chapter are: A) Cobalt complex { Co(smz)2(H20) .DMF} (3) B) Nickel complexes Ni(en)3(sdz)2 .H20 (4) and Ni(smr)2(py)2 .4py (5) C) copper complexes Cu(en)2(sdz)2 (6), Cu(dien)2(sdz)2 (7), Cu(en)2(H20)2 smr)2 (8), Cu(en)2(H20)2 smr)2 .H20 (9), Cu2(smr)4 .2DMF (10), Cu2(smr)4 .2DMSO (11), Cu(smz)2(apen) .3H2O.CH3OH (12) and { Cu(smz)2.NH3 .2H20}w (13) D) Zinc complexes Zn(smz)2(NH3)2 (14) and Zn(smz)2(py)2 .2py (15), E) Cadmium complexes Cd(dien)2(sdz)2 .DMF (16), Cd(dien)(smr)2 .H20 (17), Cd(sdz)2(bpy) (18), Cd(sdz)2(phen) (19), Cd(sdz)2(dmbpy) .2DMF (20), Cd(smr)2(phen) (21), { Cd(smz)2(H20) .DMF}/I (22), { Cd(smz)2(H20) .2H20} (23) and Cd(smz)2(en) .2DMF (24) and F) Mercury complexes Hg(sdz)2(DMF)2 (25), Hg(smr)2 (26) Hg(smr)2(bpy) (27) and Hg(smz)2(DMF)2 (28). The structural results for the complexes are discussed and compared with other related complexes. In this context, the different types of coordination geometries, important parameters within the coordination sphere, the various modes of coordination of the sulfa drugs in the anionic form, dimeric polymeric complexes, the role of hydrogen bonds in the formation of the "cation-anion pair" and the packing diagram have been discussed. In Chapter 5, we have described the syntheses and characterisation of the complexes of sulfathiazole, their analytical and spectral data along with the X-ray structure determination of these complexes are presented. The complexes studied are: (H2stz)2 N03 .H20 (29), CoCl4 (H2stz)2 .CH3COOH (30) and Cu(en)2(H20)2 stz)2 .2H20 (31). In all the complexes the sulfathiazole molecules act as ionic species. The structural results for the complexes are discussed and compared with other related complexes. In this context, the role of hydrogen bonds in the formation of the "cation-anion pair" and the packing diagram has been discussed. Chapter 6 describes the structure of sulfadimethoxine and synthesis and characterisation of a zinc complex of sulfadimethoxine Zn(sdm)2(NH3)2 .2H20 (33) by analytical and spectral data along with the X-ray structure determination. The structural results of the complex are discussed and compared with other related complexes. The packing diagram of the complex with the hydrogen bonds is discussed in this chapter.

Molybdenum based catalysts have been used successfully as catalysts for the oxidative dehydrogenation of propane to propene. Metal phosphate catalysts have also been reported to exhibit high yields of propene in the oxidative dehydrogenation of propane to propene. Therefore, MoO2HPO4.H2O was used as a precursor to prepare different bulk and supported molybdenum phosphate phases based on the methodology used in the preparation of vanadium phosphate (VPO) catalysts which are used commercially for selective butane oxidation. The materials obtained were tested as catalyst for propane oxidative dehydrogenation. MoOPO4 was prepared by a novel procedure. The unsupported molybdenum phosphates were not active for propane oxidative dehydrogenation to propene. However, the activity of the molybdenum phosphates was significantly enhanced after being impregnated on the supports (Al2O3, SiC2, TiO2 and MoO). The enhancement of the activity was attributed to the enhancement of the reducibility of the supported molybdenum phosphates. The more reducible the catalyst the more active it is. Moreover, these supported catalysts exhibited high selectivity at the initial reaction temperature. However, the selectivity decreases as the reaction temperature increases, which was attributed to a consecutive oxidation of formed propene. No crystalline phase has been detected by XRD in all supported molybdenum phosphates, which is attributed to a strong interaction between the impregnated molybdenum phosphate material and the supports. Niobia-supported molybdenum phosphate (heated in nitrogen at 500 C) exhibited the highest alkene selectivity of 51.7% (propene selectivity = 42.5% and ethene selectivity = 9.2%) at a propane conversion as high as 20%. Therefore, the propene and total alkene yield are 8.5 and 10.3%, respectively, which are comparable to that reported in the literature. Therefore, supported molybdenum phosphate catalysts are promising for propane oxidative dehydrogenation to propene. The relative performance of molybdenum phosphate supported on different supports at 500 C (heated in nitrogen to 500 C) is as follows: 20% MoPO/TiO2> 20% MoPO/Al2O3=20% MoPO/SiO2>20% MoPO/Nb205 While the selectivity to propene is as follows: 20% MoPO/Nb2O5> 20% MoPO/SiO2>20% MoPO/Al2O3>20% MoPO/TiO2. This indicates that the higher the activity the lower the selectivity, except for the silica-supported molybdenum phosphate and the alumina-supported molybdenum phosphate. They exhibited the same activity, but the silica-supported molybdenum phosphate was more selective to propene. The in situ XRD confirmed the formation of a stable amorphous phase of molybdenum phosphate when the molybdenum precursor (MoO2HPO4.H2O) was heated in nitrogen up to 400 C. Moreover, heating the amorphous phase formed up to 500 C resulted in the formation of a stable crystalline phase at 500 C. According to the JCPDS data this crystalline phase was molybdenum pyrophosphate ((MoO2)2P2O7).

The first examples of gold as the catalyst of choice were the hydrochlorination of acetylene using gold on carbon catalysts and the oxidation of carbon monoxide, both identified around 20 years ago. From that time most research interest has been focused on the use of gold as a catalyst for oxidation reactions, whereas although gold can be an excellent electrophilic agent is some of its oxidation states, few studies are available which display this. Chlorinated organic compounds are widely manufactured in industry for the production of chemicals that can be used as solvents, glues, anaesthetics, and precursor for plastics. However, the usual industrial conditions applied make use of high pressure and temperature. By focusing attention on the production of commodities like vinyl chloride monomer, and chloroethane we have seen that these kinds of products can be obtained under mild conditions when gold is used as a catalyst, and with high selectivity. Moreover, a tuneable effect can be obtained using different supports, or gold oxidation states. Although gold as a catalyst for the hydrochlorination of acetylene is known, no literature is available on the effect of adding another metal, either as a bimetallic or an alloy system, on final activity. For this reason, the effect of adding metals such as Pd, Pt, Ru, Rh, It has been investigated. Gold alone gives the most stable performance. However, when Au/Pd is used an initial promotional effect is observed. Although this effect is not a long term effect, it has been possible to detect an influence of the gold oxidation state and to identify clearly the gold oxidation state responsible for the hydrochlorination of acetylene and the mechanism of catalyst deactivation. Using carbon as a support, only carbon-carbon triple bonds are reacted and ethylene is unreactive. For this reason selectivity to vinyl chloride monomer in excess of 99% is achieved. This particular behaviour has been explained by postulating the formation of a C2H2/AU/HCI complex, and this hypothesis is supported by the use of deuterated reagents and molecular modelling investigations.

The oxidation of benzyl alcohol over supported gold, palladium and gold palladium catalysts was studied in a high-pressure stirred autoclave. Reaction conditions such as oxygen pressure and reaction temperature were varied to obtain optimum conditions for catalyst screening. Gold palladium catalysts supported on various oxides were prepared and screened with titania supported catalysts proving to be the most active. Different preparation methodologies were used to prepare titania supported bi-metallic catalysts, co-deposition precipitation methodology was found to give the most active and stable catalyst. Further gold, palladium and gold palladium catalysts were prepared supported on ceria that had been obtained from the calcination of cerium acetylacetate that had been precipitated into a supercritical carbon dioxide antisolvent. These catalysts proved to be significantly more active than those supported on the ceria form the simple calcination of the precursor. Reuse experiments showed that the supercritically prepared ceria precursor catalyst increased in activity with use, despite significant leaching of the metals, an effect not observed for the non-supercritically prepared ceria precursor catalyst. The ceria catalysts prepared by the supercritical antisolvent method displayed very high turn over frequencies for the oxidation of l-octen-3-ol, 2-octen-l-ol and cinnamyl alcohol. Gold and gold palladium catalysts supported on titania and graphite were used for the oxidation of 2,5-dimethyl furan to form hex-3-ene-2,5-dione. The effect of temperature, pressure and radical initiator were investigated and the highest selectivity was achieved at the lowest oxygen pressure. The oxidation of a-pinene to verbenone investigated, the reaction proceeded with highest conversion at high oxygen pressure with catalyst not required for the reaction to proceed. Gold palladium catalysts were used for the oxidation of isophorone and valencene using the optimized conditions established for the a-pinene reaction system. 2,6-lutidene, 2-picoline and 3-picoline were found to be poisons for gold palladium catalysts.

The adsorption, reaction and decomposition of a series of molecules (oxygen, ethylene, acetic acid, carbon monoxide and acetaldehyde) associated with vinyl acetate synthesis were investigated using a combination of ultra-high vacuum surface science techniques, including molecular beam sticking, x-ray photoelectron spectroscopy and temperature programmed desorption. The single crystal Pd (111) surface, bimetallic Au/Pd (111) surfaces prepared by metal vapour deposition and an alloyed Au30Pd70 (111) crystal were used in these studies. All the molecules investigated adsorbed onto the Pd (111) surface across a wide temperature range. Mechanisms for the reactions of each with the surface were suggested. The carbonaceous organic molecules all decomposed to deposit carbon at the surface at room temperature and above, blocking active sites to adsorption. Above a specific temperature, this carbon went subsurface and no longer inhibited subsequent adsorption of molecules. The deposited carbon could often be removed in a facile manner by oxygen treatment.

Electron Paramagnetic Resonance (EPR) spectroscopy has been used to study and identify a number of defects (eg., Ti3+, O) and transient oxygen centred radicals (eg., HO2*, ROO*, etc) formed under different co-adsorption conditions over the surface of polycrystalline Ti02 (P25). Paramagnetic surface Ti3+ centres were formed by thermal treatment of Ti02 under vacuum. This system provides a good model for probing electron transfer (ET) sites at the surface of TiC>2 that may be involved in catalysis. Upon O2 addition to the reduced surface, superoxide (O2 ) anions are formed and stabilised. Different sites for O2" stabilisation have been identified notably at oxygen vacancy sites and at a non- vacancy, high co-ordinated Ti4+ sites. ET from the precursor Ti3+ centres to O2 (forming O2") was prevented at each respective site through selective blocking using specific probe molecules (CO2 or Ar). Carbon dioxide specifically adsorbed at the non-vacancy sites, whereas Ar preferentially adsorbed at vacancy sites, thereby preventing ET. The decomposition of acetonitrile, methanol and toluene occurs under dark conditions over TiC>2 (P25) containing adsorbed O2" radicals. The reaction of the organic substrates with O2" resulted in the production of thermally unstable O2 ... substrate associated surface complexes which decayed at T > 240K. Under photochemical conditions, a series of thermally unstable alkylperoxy radicals were identified following UV irradiation of a series of co-adsorbed organic: O2 mixtures. The formation of oxygen centred radicals (CV and ROO*) and defects (O) on the dehydrated, partially and fully hydrated TiC>2 surface under photochemical conditions was investigated. The O2 radicals were formed on the dehydrated and partially hydrated surfaces. At low temperatures O2" radicals were accompanied by O defects. These O' species were thermally unstable and decayed at T > 200K, whereas 02 was stable at room temperature. The population of O2 and O" on the partially hydrated surface decreased as the water pressure increased this was caused by site blocking via adsorbed H2O and OH groups. On fully hydrated surfaces, no 02 radicals were observed. The peroxy type radical, ROO*, was also formed on the Ti02 surface under all of the investigated hydration conditions.

In this thesis, the structure and reactivity of palladium on titania has been studied on high surface area powdered materials and on low surface area models. Mathematical models have been established which relate the particle radius to various parameters such as particle surface area, density of particles, interparticle distance and coverage. The sintering process is studied through STM imaging and particle size distribution (PSD) calculation on two models. The technique resulting in PSD consists in the calculation of the particle density as a function of 4 parameters: perimeter, area, height and volume of the particle. This is done through the analysing of STM images using a build-in-house software. It is found that Cu followed the Ostwald ripening process while Pd followed the coalescence sintering. From the analysis of the Auger spectra, the growth mode of Cu and Pd were found to follow the Volmer -Weber mode consisting of 3D particle growth. The structure of the Pd/Ti02 system is investigated via STM and LEED analysis. It is shown that Pd nanoparticles supported TiC>2 reconstructed upon annealing into hexagonal, wagonwheel, star shape and zigzag superstructures. These various structures have unit cell dimensions varying from 9.5A to 25A and consist of mixed layer of titanium and palladium in their ground state. The possible structures are modelled and it is concluded that the Ti or Pd adatoms can be situated in atop, 2- or 3-fold sites. TPR results shows that CO uptake capacity is lost when the catalyst is reduced to high temperature. However, the CO oxidation reaction is enhanced. It is shown that encapsulation of Pd by TiOx species is responsible for the loss of CO adsorption but also for the improvement of the CO oxidation. Weakly bound forms of CO and new active centres, as a result of the reconstruction, can improve the activity of the CO oxidation reaction.

The chemistry of vinyl acetate synthesis from ethylene, acetic acid, and oxygen over palladium-gold catalysts has been investigated in a study which has concentrated on the use of cyclic voltammetry as a surface sensitive analytical technique. Three series of palladium-gold/graphite catalysts were prepared by slurry precipitation or by incipient wetness impregnation and by reduction with formaldehyde or hydrazine. These catalysts, which behaved similarly, contained metallic particles having bi-modal particle-size distributions and alloy compositions, as judged by X-ray diffraction, high resolution transmission electron microscopy, and energy dispersive X-ray analysis. Surface characterisation was achieved by cyclic voltammetry and X-ray photoelectron spectroscopy. In experiments intended to mimic the industrial LEAP process (in which potassium acetate is added to the reaction mixture) catalysts were treated with acetic acid or potassium acetate/acetic acid mixtures. Such treatments resulted in etching of the catalysts with consequent loss of palladium dissolution of the lost palladium as dimeric and trimeric palladium acetate complexes was confirmed by ultra-violet absorption spectroscopy. Such etching occurred at the surfaces of palladium-rich particles gold-rich particles were resistant to etching. Thus, the role of gold as a promoter is to stabilise the optimum alloy phase against loss of palladium. Reduction of palladium acetate complexes by ethylene led to plating of metallic palladium onto the surfaces of etched catalysts. Thus, a cycle of palladium dissolution and deposition occurred under reaction conditions leading to a redistribution of palladium between the catalyst particles. Palladium acetate forms complexes with acetic acid and water that are liquid at synthesis temperatures. Thus, even under gas-phase reaction conditions, a liquid-phase may be present in which palladium acetate complexes can facilitate the homogeneous catalysis of vinyl acetate synthesis. This investigation provides definitive evidence that the balance of heterogeneous and homogeneous synthesis is determined by the range of the palladium-gold alloy composition present at the surface of the active catalyst. Etching and dissolution would be avoided by suitably restricting this range, whereupon reaction would be confined to that achieved by heterogeneous catalysis.

The interaction of with clean, partially oxidised and fully oxidised Cu(110) surfaces has been studied by XPS and STM at room temperature and is compared to the reactions of 2-tertbutylaniline. Limited dissociation occurs at clean Cu(110), but at a partially oxidised surface, a chemisorbed phenylimide ((C6I I>N(a)) product is formed, together with water which desorbs. The phenyl imide forms three different (4 ()W 4 (A (4 0) domains, described by, and unit meshes. A coadsorption y2 2) y- 2) 2) of aniline and dioxygen in a 300:1 mixture results two structures, described by (3) f3 and unit meshes. In both cases, the maximum surface l-i V U V concentration predicted by STM is half that actually determined by quantification of the XPS peaks. Pi-stacking of the phenyl rings is proposed to account for this discrepancy. 2-tertbutylaniline adsorbs at partially oxidised Cu(l 10) surfaces, forming a moderately ordered p(2x2) structure. The maximum surface coverage predicted by STM is in agreement with the actual maximum surface concentration of 2.5 x 1014cm"2. The interaction of dimethylamine with clean, partially oxidised and fully oxidised Cu(110) surface at room temperature has been studied by STM and XPS. Reaction with partially oxidised Cu(110) causes reconstruction of the chemisorbed oxygen islands from the well know p(2xl)-0(a) structure to a (3x1) phase. The expanded oxygen islands desorb as water and structures orientated in the <110> direction, assigned to (CH3)2N, form in their place. The structures are stable for several minutes, after which they desorb, possibly as CIl3NCH2(g) via a P-elimination reaction. Reaction with a complete O(a) monolayer results in limited dimethylamine adsorption. Dimethylamine does not react with clean Cu(110) at room temperature. The reaction of ethylamine with clean, partially oxidized and fully oxidized Cu(110) has been studied by STM and XPS at room temperature and is compared with the reactions of diaminoethane and 2,2,2-trifluoroethylamine. Kthylamine reacts with partially oxidized Cu(110) causing expansion of the oxygen islands from p(2xl) to (3x1) structures. After a period of several minutes, the expanded oxygen islands desorb as water, leaving a clean surface. Kthylamine reacts with a full O(a) monolayer without any reconstruction, causing desorption of all surface oxygen and resulting in a clean surface. It is proposed that the ethylamine desorbs as CM3CI INI I via a p-elimination reaction. Diaminoethane reacts with partially oxidized Cu(110) in the exact same manner as ethylamine. At partially oxidized Cu(110), 2,2,2- trifluorethylamine causes desorption of all chcmisorbcd oxygen without causing any reconstruction of the oxygen islands. A clean surface is left at the end of the reaction. A full O(a) monolayer is inert to 2,2,2-trifluorethylamine. The interaction of 4,4-diaminobenzophenone, (I bNCV ICO, with clean Cu(110) surfaces has been investigated by STM and XPS at room temperature. Sub-monolayer coverages give rise to three distinct, highly ordered structures. The first can be described using by a unit mesh. 1 he others are based around a pair of (7) (7) molecules, forming and lattices. Above a monolayer, order breaks down.

Proton-deuterium exchange of the carbinol hydrogens of gluco-, manno- and galacto-methyl- ot-D-pyranosides with deuterium oxide catalysed by ultrasonicated Raney nickel had low regioselectivity. 4,6-0-Benzylidene-methyl-cc-D-glucopyranoside underwent deuteration at C- 2 and C-3 and cleavage of the benzylidene group, whereas 4,6-O-isopropylidene-methyl-a-D- glucopyranoside was deuterated exclusively at C-2 (2H-NMR), which provides a rapid and economical route to 2- 2Hi -methyl-a-D-glucopyranoside. The diol moiety of 4,6-0-benzylidene-methyl-a-D-glucopyranoside was cleaved under aqueous (sodium periodate), and non-aqueous (periodic acid) conditions to give a D-erythritol in high yield (80%, 90%). Application of similar conditions to heptakis{6-0-tert- butyldimethylsilyl)-p-cyclodextrin failed to give an isolable product. The epoxides methyl 2,3-anhydro-4,6-(9-benzylidene-methyl-a-D-mannopyranoside and /z67ta£w(2,3-anhydro)-f3-cyclomannin were prepared via the C2-tosylates. Both reacted with 4-ter/-butylbenzylthiol at the 3-position. The cyclomannin gave an adduct with xQ&,-altro stereochemistry as determined by NMR and the homogeneity was established by MALDI-MS (M+K+, m/z 3109.5, Ci6iH26602sS7Si7K). The mannopyranoside similarly reacted with L- cysteine to give a 4Ci-a//ro-amino acid sugar adduct, but the cyclomannin failed to react. The benzylidene-, isopropylidene- glucopyranosides and the silylated cyclodextrin mentioned above underwent allylation with allyl bromide, to give 2,3-di-O-allyl-glucopyranosides and heptakis(2,3-di-0-allyl)-p-CD respectively. Ring closing metathesis (RCM) with Grubb's 2nd generation catalyst of the allylated cyclodextrin yielded a complex mixture, but the allylated glucopyranosides yielded the cyclo-octenes, which were hydrogenated. Unexpectedly, the benzylidene protecting group was partially cleaved during RCM. All NMR spectra were assigned by correlation methods.