5-Acatylamino-l,2-benzoquinone 2-oxine [5-AcqoH] results from the direct nitrosation of 3-acatylaminophenol together with its isomer 3-acetylamino-l,4-benzoquinone 4-oxine [3-AcqoH]. The quinone oximic structure of the former has been indicated by i.r. and n.m.r. studies. In the case of 3-AcqoH this type of structure has been established by X-ray crystallography. Following a brief review of quinone oxinic complexes, a study of the synthesis, properties and structure of Cu(II), Ni(II), Co(III), and Mn(III) complexes of 5-AcqoH is presented. The complexes Ni(5-Acqo)2.nH2O (n = 2-6), Cu(5-Acqo)2, Co(5-Acqo)3, and Mn(5-Acqo)2, .H2O were prepared by the direct reaction of 5-AcqoH with the appropriate metal(II) chloride or by the nitrosation of 3-acetylaminophenol in the presence of the metal salt. Co(5-Acqo)3 was also prepared by the reaction of the ligand with Na3[Co(NO2)6]. The complex Na(Co(5-Acqo)2 (NO2)2 ], resulted from the nitrosation of Na3(Co(NO2)6] in the presence of 3-acetylaminophenol. Pyrolysis of Ni(5-Acqo)2.6H2O gave Ni(5-Acqo)2. The complexes Cu(5-Acqo)2 and Ni(5-Acqo)2.nH2O (n = 0, 2-6) reacted with pyridine and 2,2-dipyridyl to give adducts whereas the complexes of M(5-Acqo)3 (M = Co, Mn) showed no reaction with pyridine. Magnetochemical measurements, indicated that all complexes, [except Ni(5-Acqo)2], are magnetically dilute and hence monomeric. Ni(5-Acqo)2 complex has a subnormal magnetic moment due to association. The diamagnetism of Co(5-Acqo)3 and the low spin configuration of Mn(5-Acqo)3.H2O are indicative of the strong field character of the ligand. COSY, H- and C n.m.r. studies have shown that Co(5-Acqo)3 is a mixture of facial and meridial isomers. For all complexes i.r. studies indicate the involvement of the ring CO in bonding. Their electronic spectra show strong absorption in the u.v. region which tails into the visible but d - d transitions have been clearly Identified for Ni(5-Acqo)2.6H20 and Mn(5-Acqo)3 .H20. Reexamination of the reaction of several complexes of type M(Rqo)2 [M = Ni or Cu) with dimethyl acetylenedicarboxylate has confirmed the occurence of cycloaddition and the formation of oxazine. A metal-containing product, M(II)(butynedioate), and in some cases an additional organic product, l,4-benoxazin-2-one, have been isolated. Mechanistic appraisals for the 1,4-benoxazinone formation are presented and the structure of one has been elucidated by X-ray crystallography. The reaction of the new complex Cu(5-Acqo)2 with DMAD leads to analogous products. The reaction of the complexes M(l-nqo)2 [M = Cu, Ni) with methyl propiolate give the hydrated M(II)(propynoate)2 and oxazine.

It was at the turn of this century, within the area of co-ordination chemistry that the interdependence of structure and reactivity was first realised. The understanding of interactions between metal and ligand has become more complex progressing from simple unidentate to the more complicated multidentate systems and in some instances, ligand designs have imposed unusual co-ordination geometrics around metal atoms. Such offsets are particularly evident in macrocyclic ligands. Their intrinsic properties as ligands gives them the potential to behave as catalysts, semiconductors and sequestering agents for use in pollution control and hydrometallurgy. In addition, they have impinged on the biomedical field, where they have become likely candidates for therapeutic reagents required for the treatment of metal intoxication, or used as diagnostic agents in the form of radio-labelled macrocycle-conjugated antibodies for better tumor imaging while their specificity and efficacy prove excellent for enzyme modelling. In 1987, achievements in this expanding field culminated in the form of a Nobel prize, awarded to C. J. Pedersen, J. M. Lehn and D. J. Cram and marked the scientific world's recognition of the importance of macrocyclic chemistry. Having briefly outlined the wealth of research associated with macrocyclic ligands currently being undertaken, one aspect is of special interest to this work. The objective of this project has been to design new selective complexing agents for the toxic heavy metal ions cadmium(II), mercury(II) and lead(II). Resulting observations on the properties of such systems should provide a better insight of how and why certain ligands 'discriminate' or appear selectively to complex with only certain metal ions. In addition, the project supplements an ongoing study of related work which forms part of a series within a matrix of similar macrocyclic ligands.

A wide range of diphosphines and their complexes with chromium, molybdenum, and tungsten carbonyl moieties has been synthesised and characterised, arid studied by proton, C-13 and P-31 n.m.r. spectroscopy. In many cases the diphosphines have one or more centres of chirality, and this leads to the formation of diastereomers that are readily distinguishable by n.m.r. The P-31 chemical shifts occur in specific ranges that are often structurally diagnostic, and are interpreted in terms of 'group contributions’, 'coordination chemical shifts', and the effects of chelate 'ring strain’. In order to obtain values of geminal and vicinal P-31 to proton coupling constants which can be used to assess conformational details, recourse was had to C-13/H -1 two-dimensional heteronuclear chemical shift correlation experiments. These use effective chemical shifts introduced by the presence of a single C -13 nucleus to reduce the extent of second-order character in the spectrum and hence give values of N(PC) and N(PH) together with their relative signs. Synthetic studies have also been undertaken on the triphosphine ligand (Ph2P)2CHCH2PPhH, which has a chiral phosphorus atom, and its complexes. When all three phosphorus atoms are coordinated to the same metal atom this leads to considerable ring strain, but nonetheless such complexes are stable, but show interesting variations in their n.m.r. properties. The presence of the P-H bond in this triphosphine and its complexes permits base-catalysed addition reactions with species such as (Ph2P2)2C=CH2 to yield derivatives of the pentaphoshine [(Ph2P)2CHCH2]2PPh in a regio- and even stereo-selective manner. This behaviour has been studied, and several new complexes have been prepared and their n.m.r. properties have been determined.

The aims of this project fall into two main categories. The primary objective was the preparation and characterisation of novel [alpha]-aminophosphonic acids and their phosphonate ester derivatives. Compounds of these types are of interest because of their potential for biological activity, particularly in the area of agricultural chemistry. The second objective was to investigate the conformation of selected examples of these types of molecules in solution. This was achieved by considering the proton-proton and proton-phosphorus coupling constants. These coupling constants were obtained by the full analysis of the 1H NMR spectra. The strategy adopted for the preparation of the phosphonic acids started from the synthesis of imine precursors. The imines were prepared by condensing aminodiphenylmethane or [alpha]-methylbenzylamine with a wide variety of aldehydes and ketones, using very mild reaction conditions. The imine precursors were then reacted with diethyl (or dimethyl) phosphite to give diethyl (or dimethyl) 1-substituted-l-(diphenylmethylamino)methanephosphonates, which were isolated and characterised. The phosphonate esters prepared from the reactions of imines derived from [alpha]-methylbenzylamine were not isolated. A series of the phosphonate esters [diethyl 1-phenyl-l-(diphenylmethylamino)methanephosphonate, diethyl l-(l’-naphthyl)-l-(diphenylmethylamino)methanephosphonate and diethyl l-(1’-pyrenyl)-l-(diphenylmethylamino)methanephosphonate] were selected for full 1H NMR spectral analysis. The effects of the aromatic ring currents exerted by the extended aromatic substituents were investigated. The complex aromatic regions of the 1H NMR spectra were not analysed. The X-ray crystal structures of selected diethyl 1-substituted-1- (diphenylmethylamino)methanephosphonates, where the substituents are: phenyl, 1’-naphthyl, 9'-anthryl, I'-pyrenyl, 2'-pyrrolyl and piperonyl, were determined and are discussed. The phosphonate esters were subjected to acid-hydrolysis to yield the [alpha]-aminophosphonic acids, including l-N-phenylethylamino-l-(2'-thienyl)phosphonic acid which was prepared from the imine derived from [alpha]-methylbenzylamine. Full 1H NMR spectral analysis was carried out on [alpha]-aminopropanephosphonic acid at three different pH values. The results of these analyses are discussed and compared with the results of the NMR spectral analysis of [alpha]-aminopropanephosphinic acid.

X-ray crystallographic analyses of a group of salicylaldoxime ligands, and their copper(II) complexes were carried out. The three of the copper(II) complexes studied, bis-(2-hydroxy-5-methylbenzaldehydeoximato)copper(II), [(L1)2Cu]n, bis-(2-hydroxy-5-methylbenzophenoneoximato)copper(II), [(L5 )2Cu] and bis-(2-hydroxy-3-t-butyl-methylbenzaldehydeoximato)copper(II), [(L7 )2Cu], existed as centrosymmetric molecules, with the copper atom at crystallographic inversion centre. Two bidentate ligands produce a planar arrangement of donor atoms around the copper. The molecules reassemble macrocyclic systems, due to effective intramolecular hydrogen bonding linking the two ligands. To correlate chelating properties with intramolecular H-bond strengths an X-ray structural analysis was carried out on one ligand supplied by ICI, and thought to be 3,5-dimethyl-2-hydroxy acetophenone methoxyimine. Unexpectedly the molecule was found to be 3,5-dimethyl-4-hydroxy acetophenone methoxyimine. This was successful in explaining the anomolously low efficiency of extraction for copper(ll), shown by the related n-nonyl oxime ligand. It is thought that the presence of syn and anti isomers in 2-hydroxybenzophenone oximes accounts for the low efficiency of copper extraction shown by reagents which contain this chelating unit. The syn and anti forms, of 2-hydroxy-5-methylbenzophenone oxime (L5H) were prepared separately. Significantly both forms appear to yield [L5]2CH] when treated with Cu(CH3CO2)2.H20 in a homogeneous solution, although there are indications that formation of the complex from the syn-form is slower. Selectivity of complexation of metal ions by macrocyclic ligands were investigated. The stability constant data of zinc(II) and cadmium(II) complexes of a series of cyclic quadridentate ligands were compared. For the 15-membered N4 macrocyle L15, the propyl (L15p) and butyl (L15b) C-alkylated derivatives were synthesised for the first time, and the cadmium(II) complex of (L15b) was prepared. X-ray analysis were performed on the free ligand L15b, and the three metal complexes [Zn(L15)(NO3)(H2O)]NO3, [Cd(15)(NO3)NO3, and [Cd(L15b)(NO3)NO3. These results were then correlated with the results of stability constant measurements in discussing the probable behaviour of the ligands in the solution environment and hence to provide some insight into the effect of alkylation on the discrimination for zinc(II) over cadmium(II). The discrimation for zinc over cadmium is decreased on alkylation and the reason for this is discussed.

Experimental results are presented here for a 7017-T651 AlZnmg alloy where stress corrosion crack growth data on compact tension and double cantilever beam specimens has been obtained in distilled water, water saturated air vapour and aqueous chloride environments over a range of temperatures. The results, including fracture surface examination, are interpreted as indicating that a hydrogen embrittlement mechanism is operative whereby hydrogen, generated by a corrosion reaction, embrittles the alloy. Activation energy determinations have been made for stress corrosion crack growth at the free corrosion potential, and the activation energy results have been interpreted as indicating that the same process is rate controlling during both region I and region II crack growth. Hydrogen diffusion in AlZnMg has been investigated by electrochemical permeation and gas chromatography techniques. It was found that the sensitivity of the electrochemical permeation technique is not sufficient to detect a permeation transient due to hydrogen. However, the diffusion coefficient for hydrogen in AlZnMg was determined by gas chromatography over a range of temperatures. A critique is made of previous reported measurements of hydrogen diffusion in an AlZnMg alloy by electrochemical permeation. The average diffusion rate of hydrogen in AlZnMg alloy material using gas chromatography on hollow cylindrical specimens was determined. Finally, the surface reactions between polished AlZnMg alloy surfaces and distilled water, water saturated air vapour and aqueous chloride solutions have been Investigated to determine the rate of hydrogen production and the morphology of the reaction products. It was shown that the reaction of water saturated air vapour with the commercial AlZnMg alloy surface did not exhibit specificity with respect to grain boundary attach, unlike the specificity shown by high purity versions of these alloys. The contribution of these studies to the understanding stress corrosion crack growth by a hydrogen embrittlement mechanism is discussed.

The preparation and characterisation of several new types of tetraazamacrocycles and their copper(ll) complexes are described. Condensations of 4,8-diaza-2,3:9,10-dibenzoundecane-1,11-dione with a range of aliphatic and aromatic diamines has allowed the isolation of metal-free diimine macrocycles without recourse to metal template' or 'high dilution' techniques. In several cases these diimines were successfully reduced to yield the related tetraamine macrocycles. For the 15-membered macrocycle, 18,19,20,21-tetrahydro-17-H-tribenzo(f,j,n)(1,5,9,12)tetraazacyclopentadecine, derivatives bearing different substituents in one of the benzene rings were prepared. For the diimine ligands of this type both cationic and neutral copper(II) complexes were isolated and characterised; (the latter type result from loss of anilino protons on complex formation.) Compounds which are structurally related to the above tetraazamacrocycles are described. C-alkylation of the diimines using organolithium reagents appears to proceed regioselectively. An X-ray structure determination of the copper complex of 5,12-dimethyl-5,6,11,12, 18,19,20,21-octahydro-17-H-tribenzo (f,j,n)(1,5,9,12) tetraazacyclopentadecine shows this to be meso-dimethyl isomer. Condensation of 2,2 '-(oxalyldiimino)bisbenzophenone with diamines in the presence of copper(ll) acetate yields macrocyclic neutral copper(ll) complexes which contain a dioxo linkage between the anilino nitrogen atoms. An X-ray structure determination of [5,12-diphenyl-18,19-dioxo-9,10,17,18,19,20-hexahydrodibenzo (e,m) (1,4,8,11) tetraazacyclotetradecinato(2-)]-dimethylformamidocopper II dihydrate indicates steric crowding for the phenyl substituents on the imine carbon atoms. Polycyclic tetraza compounds result from the condensation of the cyclic tetraamines with glyoxal. A group of 20,21 and 22-membered sexadentate ligands having N402 donor sets, and 20-membered ligands with N4S2 and N6 donor sets have also been studied; e.g.: 12,13,25,26,27,28-Hexahydrotetrabenzo (e,i,o,s) (11,14,1,4,8,17) dithiatetraazacycloeicosine. Reduction of the azomethine linkages was achieved for all these ligands and cationic copper(ll) complexes have been prepared and characterised. An X-ray structure determination showed that one of the N402 tetraamine ligands uses only three of its nitrogen atoms in forming a complex with copper(II).

The investigation has consisted of two elements, one concentrating on the stabilities of metal complexes in solution, and the other on the co-ordination chemistry of some new N-donor macrocyclic ligands.

Unsymmetrical compounds of the general type: ArCH2(S)nCH2CH2OH (n = 1-4, Ar - o- or p-ClC6H4, o- or p-MeC6H4, Ph, p-MeOC6H4) have been prepared as analogues of the trisulphide PhCH2SSSCH2CH2OH which occurs naturally in the stem and root of the plant Petivcris alliacea.

A new five-membered cyclic tertiary diphosphine has been synthesised, PhPCH(=CH2)PPhCH2CH2 (X). Cis and trans isomers were observed; and the trans isomer (Xb) has been isolated and fully characterised by P-31, H-1 and C-13 n.m.r. spectroscopy.