No description available.

No description available.

No description available.

No description available.

This thesis describes work carried out on several chemical aspects of fused 1,2,3-triazin-4-ones. In the first section several sUbstituted l,2,3-benzotriazinones were prepared with a view to observing their rate of deazoniation. It ,was envisaged that a kinetic analysis of this reaction would aid the elucidation of the nature of a hitherto controversial reaction intermediate. The rate constants obtained were used to construct Hammett plots and hence calculate the reaction constants. Several pieces of evidence were obtained that suggested the intermediate was of a diradical nature. Unfortunately, this could not be substantiated by Chemically Induced Dynamic Nuclear Polarisation spectroscopy. The second section involved devising a new synthetic route for the preparation of l,2,3-thieno[ 3,4-d]triazinones since the one existing preparation gave polysubstituted products. A simple thienotriazinone was obtained which was used to study the reaction conditions required to cause its deazoniation. It was envisaged that for this reaction to occur, a potentially undesirable sulphurE[intermediate must be surmounted. As anticipated the thieno[3,4-d]triazinone did not deazoniate under the normal conditions.The synthetic route used to prepare the thieno[3,4-d]triazinone also afforded an intermediate aminonitrile. An investigation into the versatility of this compound as a potential precursor to other fused heterocycles was undertaken. Several fused thienopyrimidines were obtained. The final section of this work was dedicated to devising a synthetic route for the preparation of pyrroloand furanotriazinones. Unfortunately these compounds were not obtained due to difficulties of instability and excessive water solubility encountered in the synthesis, several useful intermediates were, however, successfully prepared.

No description available.

The syntheses of phthalocyanines and particularly substituted phthalocyanines, together with some of their main applications, are described. Asymmetrically octasubstituted phthalocyanines, where the substituents on one benzene ring differ from the substituents on the other three rings are most commonly obtained from statistical mixtures of precursors derived from phthalic acid. The synthesis of a series of such compounds together with their substituted phthalonitrile precursors containing both hydrophilic and hydrophobic side-chain substituents is discussed. This novel series of nonperipherally substituted amphiphilic phthalocyanines were shown to possess liquid crystalline properties. The various liquid crystal discotic mesophases were characterised. As a consequence of their hydrophilic-hydrophobic balance and high solubility in organic solvents, the compounds were studied as Langmuir-Blodgett films. The synthesis and Langmuir monolayer behaviour of peripherally octa-t-butylphthalocyanine is also described. The latter part of this thesis includes a discussion of the mechanisms of the synthesis of phthalocyanines from various precursors and particularly from phthalonitrile, which complements the synthetic aspects of the work. The thesis concludes with an investigation into the feasibility of a stepwise conversion of phthalonitrile precursors into the macrocycle for the preparation of asymmetrically substituted phthalocyanines.

The major part of this thesis concerns the use of relatively simple compounds used in extremely dilute solution to study solvation phenomena. Use of many spectroscopic techniques such as infrared, NMR, ultraviolet, etc., have made it possible to follow the environment of the probe throughout various mixed and pure solvent states. Simple molecules such as acetone, triethylphosphine oxide, small amides, etc., yield similar results concerning the interaction of alcohol-base and water-base systems and also provide information as to the solvation state of the probes themselves. A comparative study of the various solvent scales is included, combining information obtained during the course of this research with the various literature values. The relative merits and demerits of most of the widely-used scales such as Gutmann's Donor and Acceptor numbers, Taft's ? and ? scales, Kosower's Z values and Dimroth's ET values, etc., are discussed in the light of the various solvation parameters obtained. Of particular interest was the formation of 'clathrate hydrate' compounds, already well-established in the literature. A suitable technique was developed and is demonstrated herein for following the formation of the acetone clathrate hydrate using infrared spectroscopy. Its relevance to some theories of water structure and solvation are discussed with suggestions as to acetone's solvation structure in liquid water. A final chapter is included where techniques from the probe studies are utilised in formulating a suggested mechanism for the solvolysis of alkyl halides. These reactions already having been extensively studied by kinetic means previously relied on simple mechanisms which gave adequate mathematical results to the various rate laws. The involvement of hydrogen bonding to the solvent in no way alters the mathematics but is highly relevant to the overall operating mechanism.

Chapter 1 reviews the literature concerning the principal synthetic routes to metallacyclobutane, metallacyclobutan-3-one (?3-oxodimethyl-enonethane), and four-membered cyclic ylide complexes of platinum, palladium, and nickel, which contain the M-C-X-C ring system (X=C,S, or P). The preparation and characterisation of the first examples of metallathietane-3, 3-dioxide complexes of platinum, palladium, and nickel, [M{CHRS (O) 2CHR}L2], are presented in Chapter 2. The molecular structures of three of these complexes establish the presence of puckered four-membered rings, together with the presence of a hetero-allylic contribution to the bonding. Preliminary investigations into the reactivity of these metallathietane- 3, 3-dioxide complexes are detailed in Chapter 3. Ligand substitution reactions of the complex [Pt{CHPhS(O)2CHPh}(SEt2)2] afford a range of platinathietane-3,3-dioxide complexes. A study of the reactions of platinathietane-3,3-dioxide complexes with alkyl isocyanides shows that phenyl substituted complexes undergo ligand substitution, whereas benzoyl or methoxycarbonyl substituted complexes undergo a ring insertion reaction to afford the zwitterionic complexes [Pt{CH(C0R)S(O)2C(COR)C:- NHR'}(CNR')(L) ]. Chapter 4 describes the synthesis of platinathietane-3-oxide complexes, crystallographic and n.m.r. data indicating the presence of puckered and non-fluxional four-membered ring systems, with the sulphinyl oxygen in an equatorial environment. The sulphoxide and equatorial benzoyl groups of the complex [Pt{CH(COPh)S (O)CH(COPh)} (PPh3)2] co-ordinate to palladium (II) or rhodium (I) centres to afford five-membered chelate ring products. The final Chapter describes the synthesis of diphenyl-substituted oxo- dimethylenemethane (metallacyclobutan-3-one) complexes of platinum and palladium using the dianion K2[PhCHC(O)CHPh]. The molecular structure of the complex [Pt{?3-CHPhC(O)CHPh} (AsPh3)2] establishes the presence of an n3-oxodimethylenemethane ligand. The fluxional behaviour of these diphenyl oxodimethylenemethane complexes is shown to be dependent on the mode of substitution of the phenyl rings on the oxodimethylene methane ligand, with cis-diequatorial complexes being rigid in solution, and the trans-disubstituted complex trans- [Pt{?3 -CHPhC (O) CHPh} (PPh3)2] being fluxional.

This thesis describes the synthesis, reactivity and coordination chemistry of a range of bidentate phosphino-imine ligands. The reactivity of the resultant complexes is also probed, while testing of the complexes for catalytic activity in a range of carbon-carbon bond-forming reactions is documented. Chapter 1 introduces the concepts of 'hemi-lability' and 'trans-influence', along with heteroditopic bidentate ligands, and specifically examines imine- and phosphine-based ligands, particularly aminophosphines. The nature of the phosphorus centre in terms of its steric and electronic properties is surveyed, and the bonding of phosphines and imines with metals is discussed. A review of transition metal-catalysed olefin oligomerisation and polyketone formation then follows. Finally, the aims of this work are outlined. Chapter 2 introduces the PNP ligand {(Pri2N)2PCH2C(=NPri)CH2P(NPri2)2}, previously synthesized within the Dyer group. The reactivity and coordination chemistry of this ligand are then explored, and the reactivity of the resultant complexes probed. The complex [PdCl(Me)(PNP)] has been crystallographically characterised. Chapter 3 briefly introduces guanidines, before describing the synthesis of two new types of phosphino-imine ligand derived from bicyclic and acyclic guanidines {R2P(TBD), R = Ph, Mes, Pri 2N, Ph2N and Ph2P(DMC), respectively}. The reactivity and coordination chemistry of these ligands is then explored, with particular attention paid to the effects of varying the substituents at phosphorus in R2P(TBD). The reactivity of the resulting complexes is then documented. The molecular structures of the ligands Ph2P(TBD), (Pri2N)2P(TBD) and Ph2P(DMC), and of twenty of their complexes have been determined. Chapter 4 describes the synthesis of the new P.;N ligand Ph2P(2-IP). The reactivity and coordinationchemistry of this ligand is then appraised, as is the reactivity of the resulting complexes. The structures of four complexes of this ligand have been probed crystallographically, as has a serendipitously formed nickel complex. Chapter 5 documents the catalytic testing conducted, using the complexes prepared in the chapters 2-4.