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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies on polynuclear copper (II) complexes

Hopkins, Terence Gerrard January 1973 (has links)
A study has been made of the copper catalyst employed in the oxidative coupling of phenols and also of some polynuclear copper (II) complexes which are closely related to the catalyst system. The preparation of pyridine complexes of copper (I) halides and their characterisation by infrared spectra is described and the nature of these complexes in the solid state and in solution discussed. The preparation and properties of several new tetranuclear copper (II) complexes of the type cu4ox64L, where X is Cl or Br and L is a monodentate ligand, are described and, in addition, several of these tetranuclear complexes containing mixed halide bridges have been prepared for the first time and characterised. In theory, several of these mixed halide complexes should exhibit structural isomerism, and the two isomers of the complex cu40Cl2Br44py have been positively identified .from physical measurements. Tetranuclear copper (II) complexes have been shown to undergo halide, exchange reactions in solutions and from conductivity studies it is postulated that these complexes may well be considerably dissociated in solvents such as nitromethane. In addition, tetranuclear complexes with pyridine ligands have been shown to undergo redox decomposition reactions at temperatures above l50°C to yield copper {I) halide and a halopyridine.
2

Some aspects of the chemistry of cationic intermediates

Kemp, Graham January 1976 (has links)
A review of the chemistry of the reactions between trivalent phosphorous derivatives and sources of positive halogen is presented. The alkylation of various nucleophilic substrates has been achieved using alkoxy-tris(dimethylamino)phosphonium hexafluorophosphates. In particular a new method for the preparation of alkyl aryl ethers and alkyl aryl sulphides has been developed which is both stereospecific and proceeds without rearrangement. The alkoxy-tris(dimethylamino)phosphonium hexafluorophosphates are stable, highly crystalline solids,which can be stored for long periods of time with no sign of decomposition.
3

Studies in the co-ordination chemistry of germanium and neighbouring elements

Spencer, J. January 1973 (has links)
In the first part of this thesis, the preparation of the known, compounds trans-(Et(_3)P)(_2)Pt(X)mC(_6)H(_4)F, and trans-(Et(_3)P)(_2)Pt(X)pC(_6)H(_4)F where X = C1, SnC1(_3) and of the new compounds trans-(Et(_3)P)(_2)Pt( GeC1(_3))mC(_6)H(_4)F and trans-(Et(_3)P)(_2)Pt(GeC1(_3))pC(_6)H(_4)F is described. Attempts to prepare further such compounds where X = SiMe(_3), GeBr(_3) were unsuccessful. The mass, infra-red, proton, magnetic resonance, fluorine magnetic resonance and X-ray photoelectron spectra of these compounds were recorded and the (^19)F n.m.r. and X-ray photoelectron spectra were used to investigate the trans-effect of the group IVb ligands, in these platinum-group IVb element complexes. In the first chapter the trans-effect theory is discussed. The second chapter is concerned with the experimental details and spectral data. The results obtained are discussed in the light of other evidence for the high trans-effect in platinum(ll)-group IVb compounds in Chapter 2. In Part II, the preparation of some methyleneamino derivatives containing groups R(_2)C:N- attached to silicon, germanium and phosphorus (R = t-butyl, p-tolyl, phenyl) is described. The new compounds prepared are [R(_2)C:N](_4) Ge, (R = phenyl, p-tolyl), [Bu(_2)(^t)C:N](_x) GeX(_4-x) (x = 1,2,3; X = Br, C1), and Me(_x)Si[N:C(p-tolyl)(_2)](_4-x) (x = 1,2) (Chapter 1) and P[N:CR(_2)](_3) (R = p-tolyl, phenyl), X(_2)P[N:CR(_2)] (X = C1, Ph; R = t-butyl, phenyl, p-tolyl) and OPC1(_x) (N:CR(_2))(_3-x') (R = t-butyl, p-tolyl, phenyl; x = 0,1,2) (Chapter 2). The mass, infrared and (^1)H nuclear magnetic resonance spectra were recorded and, for the phosphorus compounds the (^31)P n.m.r. spectra were recorded. These compounds were prepared with the object of finding model systems for the study of dative N=M π-bonding nitrogen and silicon, germanium and phosphorus. The shape (linear or bent) of the M-N-C skeletons (M = silicon,germanium and phosphorus) in these moisture sensitive methyleneamino compounds could not be unambiguously determined from the n.m.r. andinfrared spectral data obtained. The mass spectral data and molecular weight determination indicated the compounds to be in a monomeric state of association (^31)P n.m.r. data are discussed with reference to analogous isocyanate, isothiocyanate and amino derivatives of phosphorus, (Chapter 2).Attempts to prepare Bu(^t)(_2) C:NMe are described in Appendix 1 and experimental techniques, instrumentation and analytical methods are described in Appendices 2,3 and 4.
4

A study by ³¹P N.M.R. of phosphorus compounds and complexes in liquid hydrogen chloride

Younger, David January 1973 (has links)
The oxidation and exchange reactions of simple phosphorus compounds and the behaviour of a range of low valent triphenylphosphine complexes of the transition metals in liquid hydrogen chloride at room temperature were studied by (^31)P nuclear magnetic resonance spectroscopy. When oxidation did occur, the phosphorus was oxidised from the +3 to the +5 oxidation state. In general, five co-ordinate fluorine containing phosphorus(V) species were produced from the oxidation of phosphorus(III) fluoride and four co-ordinate species of type PBr(_x)C1(_4-x)(^+) (O ≤ x ≤ 4) from the oxidation of phosphorus(ill) bromide or chloride. The (^31)P n.m.r. chemical shifts of the complete series PBr(_x)C1(_4-x)(^+) (O ≤ x ≤ 4) were recorded in solution for the first time, stabilised by tetrachloroborate anions in liquid hydrogen chloride. The protonation of a series of oxygen containing phosphorus (V) compounds in the solvent at room temperature was investigated using P n.m.r. spectroscopy. A measure of the "acidity" of liquid hydrogen chloride was obtained from comparison of chemical shift values with values for the protonated species in other acidic room temperature solvents. The behaviour of the boron trihalides and tetrahaloborate ions in the solvent at room temperature was studied by (^11)B n.m.r. spectroscopy. The behaviour of low valent triphenylphosphine complexes of iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium, platinum31and gold in the solvent was investigated using (^31)P n.m.r., and where appropriate (^11)B n.m.r., spectroscopy. Protonation of the iron(O)complexes Fe(CO)(_5-x)(Ph(_3)P)(_x)(x = 1,2) in the presence of the Lewis acid BC1(_3) was observed. Oxidative addition reactions took place between the iridium(l) and rhodium(l) complexes (Ph(_3)P)(_2)M(CO)C1 (M = Ir,Rh) and the solvent. Finally, the oxidation of platinum(O) to platinum(II) in reactions between tris- and tetrakis (triphenylphosphine)platinum(0) and liquid hydrogen chloride was observed. Products were characterised by elemental analysis, Raman and infrared, and (^31)P and (^11)B nuclear magnetic resonance spectroscopy.
5

The formation and reactivity of some nitrides

Jayawaera, Shanath Anarasiri Aruabada January 1969 (has links)
No description available.
6

The electron microscopy of alkali halides

Hobbs, L. W. January 1972 (has links)
The various groups into which the triterpenes are divided are defined and emphasis is placed on the structural relationships which exist between these groups. A brief description is given of the methods used in the determination of the structure of triterpenes with particular reference to β-asyrin (I), a member of the oleanane (II) group. Recent progress in the problems of biogenesis and the total synthesis of triterpenes is reviewed. All approaches, so far investigated, to the synthesis of pentacyclic triterpenes involve the fusion of two bicyclic moities representing rings A and B and rings D and E of the proposed structure. This thesis describes attempts to synthesise pentacyclic triterpenes of the oleanane (II) group, via the tetracyclic-cis-ketone (IIIa), the tetracyclic-trans-ketone (IIIc) or the tetracyclic-αβ-unsaturated-ketone (IVa).
7

Studies of the influence of nitric oxide on radiation-induced reactions

Knight, R. J. January 1966 (has links)
No description available.
8

The reactions of iodine atoms in the gas phase

Musgrave, R. G. January 1966 (has links)
No description available.
9

Trigonal based copper sites - a natural situation?

Coyle, Joanne Lyssa January 2000 (has links)
This thesis is concerned with the synthesis and characterisation of copper model compounds which are of interest in a biological context. These model compounds fall into two main classes; iminopodands and azacryptands. The iminopodands are derived from the condensation of tris(2- aminoethy1)amine (tren) or tris(3-aminoisopropy1)amine (trpn) and a range of aromatic aldehydes. The compounds invariably co-ordinated Cu(1) and the structural consequences of the flexibility are examined and systematised. Their redox properties have also been studied and correlated with their structure. The main topic of this thesis concerns average valence dicopper cryptates. The synthesis has been studied in full including a description of likely decomposition and/or by-products. Considerable attention has been given to the spectroscopy of the average valence dicopper cryptates; Resonance Raman, ESRENTIOR and solution and solid state NMR have been described. Two additional properties which have been given serious attention are the redox chemistry and electron self exchange kinetics because of the relevance of these properties to the natural sites we are attempting to model i.e. the Cu<sub>A</sub> site of cytochrome c oxidase. In the final chapter preliminary experiments to synthesise a thiolate cryptand are reported in an attempt to model a S(cysteine) bridging function now known to exist in Cu<sub>A</sub>.
10

The role of free radicals in hair bleaching and damage

Clarke, Kristy January 2006 (has links)
No description available.

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