Chapter 1: The basic principle of nmr are described and some of the techniques and applications of 31P nmr are given. 31P chemical shifts for monotertiaryphosphine coordination compounds are tabulated. Chapter 2: After a brief survey of monotertiary phosphine complexes of ruthenium, the preparation of the compounds RuX2L3(L = PEtPh2), RuX2L4(L = PMePh2, Me2Ph) and Ru2X4L5(L = PC1Ph2, PEt2Ph) by the reaction of tertiaryphosphine with RuX2(PPh3)3 or 4 (X = C1,Br) in hexane or light petroleum is reported. The structures and rearrangement reactions of these compounds in polar and non-polar media are examined chiefly by means of 31P nmr spectroscopy and possible mechanisms for the rearrangements are discussed. In non-polar solvents RuCl2(PPh3)3 loses a PPh3 group whereas in highly polar solvents dissociation of a chloride ligand occurs. RuCl2(PEtPh2)3 rearranges to [Ru2C13(PEtPh2)6]Cl in polar solvents and to Ru2C14(PEtPh2)5 in non-polar solvents. RuCl2(PMePh2)4 rearranges in solution to form Ru2Cl4(PMePh2)5 and [Ru2Cl3(PMePh2)6]Cl. cis-RuC12(PMe2Ph)4 readily rearranges to [Ru2Cl3(PMe2Ph)6]Cl. Chapter 3: The preparations of the complexes Ru2Cl4(CS)2(PPh3)4 and Ru2Cl4CS(PPh3)4 are given. A mechanism involving the 5 co-ordinate intermediate "RuC12CS(PPh3)2" is invoked to explain their formation and also that of Ru2Cl4(CS)2(PPh3)3 from Ru2Cl4(CS)2(PPh3)4. RuZCl5CS(PPh3)3 is formed from Ru2C14CS(PPh3)4 by intermolecular displacement of PPh3 by Cl. Chapter 4: RUM2CO(PPh3)2dmf dissolves in non-polar solvents to form the five coordinate "RuC12CO(PPh3)2". This is used to verify the rearrangement mechanism proposed in chapter 3 by synthesising the corresponding carbonyl complexes Ru2Cl4(CO)2(PPh3)3 and Ru2C14CO(PPh3)4. In polar solvents [Ru2C13(CO)2(PPh3)4]+ is formed. 31P nmr is used to study these reactions. Equimolar quantities of RuCl2CO(PPh3)Zdmfand RuBr2(PPh3)3 (or RuBr2CO(PPh3)2dmf and RuC12(PPh3)3) react to form Ru2Br2Cl2CO(PPh3)4. Chapter 5: RuCl2CO(PEtPh2)3dmf is prepared as the corresponding PPh3 complex. It rearranges in a similar manner and although the products may not be obtained in pure form they may be identified by 31P nmr. [Ru2C1ACcJPEtPh2)4]+ forms more readily than its PPh3 analogue. RuC12CO(PEtPh2)3 is also formed as a major product in these reactions.

Five aminophosphine complexes of Ru(II) have been prepared as potential chemotherapeutic agents and characterised by NMR and X-ray crystallography. The chelate ring-opening process of the bidentate aminophosphine ligand in the complex <i>cis</i>, <i>trans</i>-[Ru(H₂NCH₂CH₂PPh₂-<i>N,P</i>)₂Cl₂ has been investigated by 2D NMR methods. The complex undergoes a ring-opening reaction in coordinating solvents via the cleaving of the Ru-N bond. This exposes a potential binding site on the metal, and leads to the possibility of <i>in vivo</i> reactivity. A range of water-soluble Ru(II)arene complexes of the type [(h⁶-arene)Ru^IIX(L-L)]^- [(h⁶-arene)Ru^IIX(L)₂]^- and [(h⁶-arene)Ru^IIX₂L], arene = benzene, <i>p</i>-cymene, alkylbenzoate, biphenyl, L-L = ethylenediamine, L = acetonitrile, isonicotinamide, X=Cl, Br, I, have been synthesised with an aim to produce anticancer active agents. They have been characterised by NMR and X-ray crystallography. The hydrolysis of [(h⁶-<i>p-</i>cymene)Ru^IICl(en)]⁺ and [(h⁶-biphenyl)Ru^IICl(en)]⁺ has been followed by HPLC and ESI-MS and an HPLC assay developed for use in studies relating to biological testing. The reactions of a range of Ru(II)arene complexes with the nucleotides 5'GMP, 5'CMP, 5'AMP and 5'TMP have been investigated by NMR. The complex [(h⁶-<i>p-</i>cymene)Ru^IICl(en)]⁺ binds to 5'GMP at the N⁷ of the guanine moiety. On reaction with a 14mer duplex oligonucleotide of known sequence it was found to lower the melting temperature of the duplex significantly to a level comparable to cisplatin. The complex forms mono and bis adducts with the oligonucleotide in a guanine specific manner, as elucidated by HPLC separation, ESI mass spectrometry and enzymatic digestion. Cytotoxic studies on Ru(II) compounds revealed a significant effect against the ovarian cancer cell line A2780. Cross resistance studies indicate that the complex [(h⁶-<i>p</i>-cymene)Ru^IICl(en)]⁺ is influenced by the protein p53, but ([h⁶-biphenyl)Ru^IICl(en)]⁺possibly functions as an inhibitor of topoisomerases.

Reactions of triethyl or trimethyl phosphite with 2-aryl-1-phenyl-a-nitroethenes at elevated temperatures gave small yields only of non-phosphorus-containing heterocyclic compounds. Observation of the reactions by n.m.r. spectroscopy, however, showed that 3,4-diaryl-4,5-dihydro-1,2,5-oxazaphosph(v)ole-2-oxides were formed, and subsequently decomposed, under the reaction conditions. The use of t-butanol as solvent for the reaction enabled a range of novel 4, 5-dihydro-1, 2, 5oxazaphosph(v)ole-2-oxides to be prepared and isolated at room temperature. The reaction was extended by the use of dimethyl phenylphosphonite and 2-phenyl-1, 3, 2dioxaphospholan, instead of trialkyl phosphites. Further investigations, of the thermolysis of the 1, 2, 5-oxazaphosph(v)ole-2oxides and their reactions with tervalent phosphorus reagents, suggested that the compounds were not intermediates in the formation of the non-phosphorus-containing heterocycles isolated previously. The results suggested that the reaction of a tervalent phosphorus reagent with a 2-aryl-l-phenyl-l-nitroethene involves two competing pathways:- Michael-type addition of the phosphorus reagent to the nitroethene, with the possibility of subsequent ring-closure to give a 4,5-dihydro-1,2,5-oxazaphosph(v)ole-2-oxide, or deoxygenation of the nitro-group to give a vinyl nitrene, and hence nitrene-derived products. The thermolyses of two aryl 2-azidophenyl ethers in triethyl phosphate were found to give significantly different yields of products than the corresponding reactions in decalin. The possible formation of a zwitterionic nitrene-phosphate adduct as a reactive intermediate seems to be insufficient explanation of the observed results. Reaction of N-t-butylphenylnitroxyl and diphenylnitroxyl with triethyl phosphite, in ethanol or methanol saturated with lithium chloride, gave ring-chlorinated anilines. This was taken as evidence in support of a reaction mechanism in which pairs of aminyl radicals undergo an electron-transfer reaction to give an aailino-anion and a delocalised nitrenium ion, which readily undergoes nucleophilic aromatic substitution by the solvent or chloride ion. The decomposition of 1, 4-di-t-butyl-1, 4-bisphenyltetraz-2-ene in ethanol or methanol also gave ring-substituted N-t-butylanilines.

No description available.

No description available.

The solvothermal syntheses, in which reactions are performed in sealed vessels at temperatures greater than the solvent’s atmospheric pressure boiling point, of new VIII and CrIII clusters are reported. This technique has been shown to overcome difficulties associated with the air sensitivity and kinetic inertness of the two ions respectively. Chapter 2 describes the synthesis of an iso-structural series of Lindqvist type structures, of general formula (Hpy)2[M6O(thme)4Cl6], by reaction of the simple starting materials [MCl3(thf)3] (M = V, Cr and Fe) with pyridine, followed by addition of the triolate pro-ligand H3thme. The magnetic behaviour of these clusters was investigated and was shown to be dominated by anti-ferromagnetic exchange between the metal ions, resulting in singlet S = 0 ground states. The incorporation of chelating bipyridine in the synthesis and variation of reaction conditions described in chapter 3 yields “metal centred stars” such as [Cr4(tmp)2(bpy)3Cl6], for a range of triolato ligands. This triangular arrangement of ions was previously reported for FeIII and subsequently became one of the most well-studied single molecule magnets (SMMs). Magnetic susceptibility measurements exhibit behavior consistent with predominantly anti-ferromagnetic coupling interactions between metal centres and a resulting S = 3 ground state, however SMM behaviour was not observed. Some novel trithiolate cluster chemistry is discussed in chapter 4, including the synthesis of a range of thiolate bridged clusters, including [V3O(tmme)2(bpy)2Cl] and (HNEt3)2[V4O(tmme)4]. These are the first VIII-tmme clusters and display the rare three-coordinate T-shaped, and four-coordinate square-planar oxide coordination geometries. Magnetic measurements suggest incredibly strong antiferromagnetic exchange (> 200 cm-1) between adjacent vanadium ions in the preceding clusters, resulting in a triplet S = 1 ground state for the trimer and a diamagnetic response for the tetramer. DFT calculations suggest this behaviour is due to very strong V-S-V super-exchange rather than the formation of metal-metal bonds. The reactions of pro-ligands known to promote cluster formation, such as triethanolamine and p-tert-butylthiacalix[4]arene are discussed in chapter 5, and the first VIII and CrIII clusters directed by these ligands are reported.

The crystal growth of the nanoporous zeolite L has been studied in this work using atomic force microscopy (AFM) to investigate late-phase crystallization processes occurring on its surface. The nanometer resolution of the AFM has identified the twodimensionallayer- by-Iayer growth mechanism of this zeolite on the {001} face, however the {1~O} face displays a previously unreported mode of attachment for this mechanism. The probability for growth in the long, c axis of the crystal is thousands of times more likely than growth in the orthogonal, a direction. Growth on this face was found to occur via the incorporation of cancrinite columns, with a measured step height of 1.2 nrn. The frustrated a-directional growth of the crystal can occur only by the bridging connection of two adjacent cancrinite columns, affording terraces 1.6 nm in height. The modification of the crystal growth mechanism of zeolite L was studied when its habit was modified with respect to the length and diameter of these hexagonal cylinder-shaped crystals. By varying synthetic parameters such as the composition and reaction time, controlled modifications in crystal habit could be observed. By studying the surfaces of a vast array of crystals, the alteration in growth mechanism and defect formation were identified. Extensive holes and cracks were observed on the surface of the {001} face that were formed as a consequence of low supersaturation conditions. The increased understanding of the growth mechanism of zeolite L was utilised to impart control over the resultant crystal habit by the addition of 21-crown-7. The function of this crown ether is likely to facilitate the lateral growth of cancrinite columns on the {1~O} face resulting in crystals that have decreased length and increased diameter. The first in-situ surface dissolution study of zeolite L was performed. The observation of a high degree of friction, detected exclusively on the dissolving parts of the crystal, enabled a detailed quantitative investigation to be carried out. This study provided evidence about the fine structural modification of the surface during dissolution on the {100} face. Additionally, the first methodology for calculating enthalpies for dissolution, activation energies, orders of reaction and dissolution rates from the friction data provided by AFM has been reported. A 1.6 nm terrace on the {10Q} face of zeolite L under basic conditions was found to dissolve with a total enthalpy of dissolution of 216 kJ mot", an activation energy of 25 kJ mer' and an order of reaction of 0.31. The dissolution, rate of the terrace was found to vary when the pH, applied load and temperature were varied.

This thesis encompasses two distinct areas of chemistry. The first part involves the synthesis and characterisation of phenylselenium(II) halides and pseudohalides and their further reactions with tertiary phosphines. The molecular structures of phenylselenium(II) chloride and thiocyanide are reported along with a large series of reactions involving phenylselenium(lI) chloride with tertiary phosphines. In addition to an extensive study of the products in solution using multinuclear NMR, suitable crystals were characterised using X-ray crystallography, yielding three novel crystal structures, two of which feature the rare [PhSeCI2] anion. The effect of doubling the starting quantity of phenylselenium(ll) chloride was noted to have the effect of encouraging more compounds containing the [R3PSePh] cation. The second part of the work incorporates the synthesis and characterisation of a series of hydrophobic bispidone - transition metal complexes. This study was the first example of bispidone ligands substituted with long alkyl chains and three novel crystal structures are reported. Their molecular configuration shows that each adopts the expected back-to-back double chair backbone as observed in similar studies by other chemists. Furthermore, the molecular structures of four piperidone precursor molecules were obtained, the first examples of piperidones substituted with hydrophobic alkyl chains. Their structures reveal that these molecules tautomerise in the solid state due to the formation of an intramolecular six-membered ring stabilised by hydrogen bonding.

No description available.

No description available.