The crystal and molecular structures of five binary complexes between transition-metal ions and 5'-ribonucleotides have been determined by X-ray crystallographic means. All data were collected by diffractometry and the structures refined by the full-matrix least-squares method. The complex Ni (C10H11N4O8P) (H2O) 5. 2H2O crystallizes in the orthorhombic space group P212121 with four molecules in a unit cell of dimensions a = 6.853(1), b = 10.812(2), c = 25.925 (3) Å. Refinement converged with R and Rw values of 0.054 and 0.059 respectively. The structure is monomeric with nickel octahedrally co-ordinated to N(7) of the base and to five water molecules. The monomer is stabilized by three intramolecular hydrogen bonds involving co-ordinated water molecules, phosphate oxygens, and the exocyclic O (6) atom of the base. The complex of empirical formula CO (C9H12N3O8P) (H2O) crystallizes in the monoclinic space group P21 with two formula units in a unit cell of dimensions a = 10.002(1), b = 7.459(2), c = 9.429(1) Å, β = 96.58(11°. The final R and Rw values were 0.073 and 0.063 respectively. The structure is polymeric in two dimensions. The cobalt is in a distorted tetrahedral environment, being co-ordinated to N (3) of the base, two oxygens of two different phosphate groups, and a water molecule. There is a weak interaction between the metal ion and the exocyclic 0 (2) atom of the base. The complex of empirical formula Cd(C9H12N3O8P) (H2O) .H2O crystallizes in the orthorhombic space group P212121 with four formula units in a unit cell of dimensions A = 5.294(1), b = 17.070(1), c = 16.371(1) Å. Final R and Rw values of 0.038 and 0.045 respectively were obtained. The structure is polymeric in three dimensions. The cadmium is in a distorted square-pyramidal environment, being co-ordinated to N (3) of the base, three oxygen atoms of three phosphate groups, and a water molecule, There is a weak interaction between the metal ion and the O (2) atom of the base. The complex of empirical formula Cu (C10H11N4O8P). H2O crystallizes in the orthorhombic space group P212121 with four formula units in a unit cell of dimensions a = 17.412 (3), b = 15.772(3), c = 5.077(1) Å. Refinement returned R and Rw values of 0.083 and 0.061 respectively. The structure is polymeric in one dimension. The copper is co-ordinated to N (7) of the base and three oxygens of three phosphate groups. Weak axial bonds to a further phosphate oxygen and the exocyclic O(6) atom of the base complete the pseudo octahedral co-ordination geometry (4 + 1 + 1). The complex of empirical formula Cu3(C10H12N5O8P)3- (H2O)8.4H2O crystallizes in the orthorhombic space group P21212 with four formula units in a unit cell of dimensions a = 20.813(4), b = 23.356(3), c = 11.392(1) Å. The final R and Rw values were 0.11 and 0.09 respectively. The structure consists of irregular helical chains. Each of the tree independent coppers is in a square-pyramidal environment, with N (7) of the bases occupying the axial positions. Whereas the square-planes of two of the coppers each consists of one phosphate oxygen and three water molecules, that of the third consists of two oxygens from two phosphates, and two water molecules. The structure is stabilized by intramolecular hydrogen bonds involving co-ordinated water molecules, phosphate oxygens, and the exocyclic O(6) atoms of the bases. A system has been devised for classifying the structures of binary metal/ribonucleotide complexes.

The reaction of chloranil with various substituted phenols under basic conditions has been studied. It has been found that the yields of benzobisbenzofuranquinonoid (1) derivatives are greater when after initial nucleophilic attack on the ketoenoid system by the oxygen atom of the phenoxide ion, the carbon atom ortho to the vinyl-aryl ether linkage is activated towards further nucleophilic attack by the presence of a suitably orientated electron releasing substituent. The other products of the reaction mixture have been isolated and characterised, and the spectral data discussed for the derivatives of 2,3-diethoxydi-benzofuran-1,4-quinone which were obtained in this way. The mass spectra of benzobisbenzofuranquinones and the corresponding quinol acetates have been examined. Facile loss methyl radicals from aromatic methoxy groups and ketene from the acetate derivatives was observed. Decarbonylation and fragmentation involving the heterocyclic ring system resulted in peaks of only minor intensity. The ready loss of substituents as described above is explained by the resulting formation of resonance stabilized quinonoid ions. Some chemical constituents of Peniophora gigantea have been isolated and characterised. 2',3',6'-Trimethoxy-p-terphenyl (25) was obtained which represents the first methoxylated p-terphenyl isolated from a fungus. Also obtained was a mixture comprising two compounds, C30H48 and C30H50. On mass spectral grounds these are proposed to be the pentacyclic triterpenes, lupa-15,19(22)-diene (33) and lup-19(22)-ene (34) respectively. 14,15-Epoxy-2-ketomanoyl oxide (44) has been microbiologically hydroxylated by Calonectria decora to form 1β,7α-dihydroxy-14,15-epoxy-2-ketomanoyl oxide (45). The positions of the hydroxyl groups were determined from the peaks arising from fragmentations in rings A and B in the mass spectrum. Strong intramolecular hydrogen bonding observed in the i.r. spectrum supported the equatorial conformation of the hydroxy group at Cl whilst the facile loss of water upon electron impact and the presence of a signal corresponding to an equatorial carbinol proton in the n.m.r. infers that at C7 is axial. Finally, it has been proposed that the structures of the blue pigments, corticins A and B, isolated from Corticium caeruleum by Dean are 2,6,9-trihydroxy-3,8,12-trimethoxybenzo[1,2-b:4,5-b']bisbenzofuran and 2,3,8,9-tetramethoxybenzo[1,2-b:4,5-b']bisbenzofuran-6,12-dione respectively. The n.m.r. spectrum of corticin A triacetate and comparison of the mass spectra of these compounds and those authentic samples prepared synthetically support these structures. Erratum p105 para 1: Should read (R=Ac).

The metal ion catalysed aquation of the trisoxalatochromium(III) ion has been studied in the presence and absence of added electrolytes with emphasis on the copper(II) ion catalysed aquation. The interpretation of the observed catalytic effects of the copper(II) ion, has been attempted in terms of ion association. The proposed scheme, for the aquation, involves metallation of the CrOX33- species to account for the promoting effect of the copper(II) ions. The specific rates of aquation and formation constants of the various species formed between the copper(II) ion and the CrOX33- ion have been obtained using curve fitting techniques. Further, the dependence of the formation constants and the specific rates of aquation on temperature has been shown to yield realistic thermodynamic and activation parameters for the proposed model. Increasing the pH was found to have an accelerating affect on the aquation of the trisoxalatochromium(III) ion at constant copper ion concentration. This has been discussed, using ion association, in terms of catalysis of the aquation reaction by hydrolysis products of the copper(II) ion, in particular the CuOH+ ion. The catalysed and uncatalysed isomeristion of the bisoxalatochromium(III) ion has been investigated in the presence and absence of various electrolytes and the kinetic data has been rationalized in terms of an ion association model. It has also been proposed, from comparisons of studies on the copper(II) ion catalyes aquation and racemisation of the trisoxalatochromium(III) ion, that a copper(II) ion associates with the CrOX33- ion through three carboxyl oxygen atoms, one from each oxalate group to form a monometallated species. Further comparison of these studies has led us to postulate, in the aquation, that a second copper(II) ion, proposed to associate with the monometallated species, associates with two carbonyl oxygen atoms of one of the oxalate groups of the CrOX33- ion. This, and the comparison of the specific rates of aquation of the monometallated and bimetallated species, led us to the conclusion that aquation occurs by a rapid one ended dissociation of an oxalate ligand followed by a rate determining loss of the oxalate group. A number of other results of relevance to the substitution and rearrangement reactions of chromium(III)-oxalate complexes, have also been included.

The triterpene precursor, 12-methoxypodocarpa-8,11,13-trien-3-one (46)*, has been prepared via the 3a-alcohol (48) formed by opening of the 3a,4a-epoxide (13) with lithium diethylamide. The total synthesis of the methyl ether of the natural product, (+)-hinokione, has been achieved by a similar sequence involving prior addition of an isopropyl group at C 13 of the methoxy acid (4) ( Scheme 1 ) . A study of the boron trifluoride rearrangements of the three epoxides (12), (13), and (14), has been made using benzene and dimethyl sulphoxide as solvents. The stereochemistry of a series of 6-bromo-7-oxo derivatives of diterpenoids possessing an aromatic ring-C is discussed and the assignment of configuration of the 6-bromo substituents from n.m.r. and n.0.e. data is examined. A preliminary investigation into the possibility of preparing a 9a-methyl steroidal analogue by addition of a cyclopentatone ring across positions 3 and 4 of ring-A of the podocarpic system is also reported.

The radiation chemistry of cysteamine and of cysteamine-S- phosphoric acid in oxygen-free and oxygenated solution has been studied at acidic and near-neutral pH. In oxygen-free solution and in oxygenated solution above pH 5 the mechanism of cysteamine radiolysis appears similar to that of cysteine. From measurements of the dependence of G(-RSH), G(RSSR), and G(H2O2) upon pH and cysteamine concentration, suggestions regarding the stoichiometry of the chain reaction occurring at higher pH and the mechanistic implications have been made. The dependence of the rate of oxidation of cysteamine by hydrogen peroxide upon pH has been studied, second-order kinetics being observed over the pH range 6.5 to 10.9, and the rate has been found to depend in a simple manner upon ionisation of the thiol. The rate constant of the reaction of aquated electrons with cysteamine-S-phosphoric acid has been measured as about 5 x 109 M-1 sec-1 by competition with cysteamine at pH 4.2, and measurements have indicated the formation of orthophosphate, inorganic phosphorothioate, and an aldehyde as products of the reaction of hydroxyl radicals with cysteamine-S-phosphoric acid at pH 8.6.

This thesis is concerned with the solvent extraction of ternary complexes of cobalt(II) and nickel(II). In a preliminary survey, the extraction of nickel(II) by a variety of systems containing carboxylic acids in the presence of 1,2-diaminoethanes was investigated in order to determine the extent to which these complexes extract into different solvents. The aromatic carboxylic acids studied were benzoic, p-toluic, phenylacetic, cinnamic, anthranilic and salicylic acid while the aliphatic acids studied were butanoic, hexanoic, octanoic, decanoic, dodecanoic, 2-bromohexanoic, 2-bromöoctanoic, chloroacetic and 2-chloropropanoic acid. The 1,2-diaminoethane used in conjunction with these acids were ethylenediamine, 1,2-diaminopropane, 1,2-diamino-2-methylpropane, 1,2-diaminocyclohexane, N,N'-diaminoethylenediamine, N,N-diaminoethylenediamine and N,N,N',N'-tetramethylethylenediamine. Of the aromatic ternary systems studied, salicylic acid with either 1,2-diaminocyclohexane or a N-substituted diamine were found to give the highest extraction. These were then investigated in depth to determine the number and nature of the extracted species. Unlike the aromatic acids, the longer chain n-carboxylic acids are capable of quantitative extraction in the absence of a diamine. During the course of this part of the project it therefore became necessary to investigate the extraction of nickel(II) both by the acids alone and by the acids in combination with a diamine. It was found that the inclusion of a diamine had little influence on the pH of extraction. Finally, the extraction of cobalt(II) by combination of salicylic acid and N,N'-dimethylethylenediamine and N,N,N',N'-tetramethylethylenediamine and by decanoic acid alone were investigated. The behaviour of cobalt(II) and nickel(II) in equivalent systems were compared in order to assess the degree of separation obtainable.

The acid catalysed aquation of potassium trismalonatochromium(III) and potassium bismalonatodiaquochromium(III) have been studied. Almost linear plots of log kobs against the Hammett acidity function were interpreted as being due to an A-1 mechanism operating. Two kinetically different types of co-ordinated oxygen were found in a study of the oxygen exchange between the trisoxalatocobalt(III) anion and 0-18 enriched water. The carbonyl, or outer, oxygen atoms are thought to exchange by an A-2 bimolecular mechanism, while the carboxyl, or inner, oxygen atoms are thought to exchange indirectly by co-ordination of enriched oxalate groups to the cobalt centre during the anation reaction of the bisoxalatodiaquocobalt(III) ion. Finally, oxygen exchange reactions between 0-18 enriched water and various carbonato-ammine cobalt(III) complexes were studied, and it was found that generally the three oxygen atoms of the co-ordinated carbonate exchanged at equal rates, an exception being in the case of the carbonatobis(o-phenanthroline)Co(III) ion where the outer, carbonyl, oxygen exchanged faster than the inner, metal-bound, oxygen atoms. The first of these two groups has been interpreted in terms of a fast, reversible one ended dissociation process occurring, which is much faster than oxygen exchange, and the latter case in terms of a rate determining one ended dissociation step.

Primary and secondary amines react with pentachlorocyclopropane to form a variety of novel products. Amidines, allyl and cyclopropenyl cations are easily reached by these reactions. The 1,1,3,3-tetra-aminoallyl cations of this series can be reversibly protonated at C(2) to give diamidinium ions. Action of KOH on the diamidinium species CH2[C(NHBut)2]2 2+ produces the diamidine CH2[C(NBut)(NHBut)]2 which hydrolyses to the formamidine CH(NBut)(NHBut). Bis- and tris-amino substituted Cyclopropenylium ions are formed by the action of secondary amines on pentachlorocyclopropane. The cations of this study are stabilised by electron back-donation from nitrogen atoms of substituent groups- The subject of back-bonding was probed in several ways. crystallographically determined structures of representative salts afforded bond length data from which deductions about back-bonding were made. The measurement of barriers to bond rotation is another way that this effect was investigated. Using the technique of variable temperatue NMR, VT-NMR, spectroscopy, energies of activation about unsaturated bonds of allyl, amidinium and cyclopropenylium cations were found. UV-spectra provided additional information concerning bonding in these species. Tautomerism of N,N’-disubstituted amidines was investigated by VT-NMR spectroscopy. Individual tautomers were identified in NMR spectra (13C,1H). Tris-alkylaminocyclopropenylium ions were oxidised to form intensely coloured radical dications. The first Raman spectrum of a cyclopropenyl radical dication was determined. Using the technique of pulse radiolysis we were able to reduce the cyclopropenylium cation, [C3(Net2)3]+, to the molecular radical. Further, pulse experiments enabled standard reduction potentials of representative [C3(NR2)3]2+ and allyl radical dications to be measured and compared. In general, tertiary amines reacted with pentachlorocyclopropane to generate product mixtures. Reaction of para-dimethylaminopyridine, DMAP, on pentachlorocyclopropane was a case in exception. The novel allylide product is the same as that formed via an alternative route. The direct reaction of ammonia on pentachlorocyclopropane product several products including the formamidine NC-N=CH-NH2. A polyamide was prepared from the hydrolysis of a diamidinium ion. The mechanism of formation and the characterisation of this glossy, thermoplastic material is discussed.

The present interest in organometallic nitrosyl complexes stems partly from their similarity with carbonyl analogues which are widely used as catalysts in industrial processes. The search for potential new catalysts among nitrosyl complexes is perhaps not surprising when it is realised that the nitrosonium ion (NO+), the species normally regarded as being co-ordinated, is isoelectronic with carbon monoxide. Further interest may be due to the fact that NO+ is also isoelectronic with molecular nitrogen and hence nitrosyl complexes may be suitable as models for co-ordinated nitrogen in the process of nitrogen fixation. In their own right nitrosyl complexes pose problems of chemical interest concerned with their structure and the bonding associated with the metal-nitrosyl bond. As part of an investigation into the geometry of co-ordinated nitrosyl this thesis presents structural data for several nitrosyl complexes of Group VIII metals .. In addition the mode of binding of the isocyanide group has been studied as well as the associated stereochemistry of the metals ruthenium, osmium and iridium. To date, structural studies have established three different modes of co-ordination for the nitrosyl group. Probably the most common involves a linear arrangement of metal, nitrogen and oxygen, the effective coordinating species being regarded as the diamagnetic nitrosonium ion (NO+).

The reactions between tritium gas and organic substrates sorbed on irradiated silica gel have been studied. It has been found that tritium gas, when admitted to gamma-irradiated silica gel, is adsorbed on radiation-induced sites on the solid and bleaches the blue colour of the solid. The sorbed tritium becomes activated to at least two forms; one capable of exchange with alkanes such as 2 methylbutane and both capable of exchange with toluene and 2 chloro2methylbutane. High levels of tritium were incorporated into 2 methylbutane, 2 chloro2methylbutane and toluene, up to 32±2%, 95% and 100% of the total tritium present, respectively, being incorporated (using 2 g SiO2, irradiated 15h), with high standards of radiochemical purity, (97±1% for 2 methylbutane). Yields of labelled hydrocarbons were found to be sensitive to the conditions under which the silica gel was degassed before irradiation; optimum degassing conditions being evacuation for one hour at 973 K. Yields were also found to be dependent on the quantities of silica gel and tritium used and on the radiation dose given the silica gel, all three of these being increased concurrently for maxim yields to be obtained. In a study of the labelling of hydrocarbons of different structures it was found that alkanes containing a tertiary carbon atom were labeled heavily compared to straight-chain hydrocarbons; activity yields of the substrate hydrocarbon decreasing with increasing molecular size, to insignificant values with hydrocarbons heavier than 2 methylhexane. Unsaturated hydrocarbons such as hex-1-ene were found to undergo hydrogenation on irradiated silica gel to produce labelled alkanes; branched-chain alkenes undergoing double-bond isomerization. Reaction mechanisms for tritium activation and exchange have been proposed, involving ionization of tritium by radiation-induced positive holes in the solid and exchange of the ionic species with carbonium ion intermediates. It has also been established that gamma-irradiated alkali halides do not promote exchange of tritium gas with alkanes.