Information from solubility, spectroscopy and kinetic studies has been used to characterize solvation for three groups of complexes. These three groups include metal-d6 diimine complexes, metallocenes (M(Cp)2Cl2 where M = Ti(IV), V(IV) and Zr(IV)), and binuclear complexes involving d6-metal ions with n-acceptor bridging ligands. The discussion of the first group deals mainly with Mo(0), and also with a few Mn(I) analogues. Solubilities, from which transfer chemical potentials are derived, have been measured in various pure and mixed solvents. Information about charge transfer spectra, carbonyl stretching frequencies and n.m.r chemical shifts (several nuclei) are reported. The results clearly indicate solvent dependence. Kinetics of substitution reactions involving formation from Mo ( CO)5 (4CNpy) or from Mn(CO)5Br and substitution of Mo(CO)4(diimine) complexes have been studied in various solvents. The solvent sensitivities of reactivity of the latter process are analysed, based on initial state-transition state contributions for these reactions of well-established mechanism. Pressure effects on reactivity, and on charge transfer spectra of complexes in this first group, have been investigated. Kinetics of reaction between M(Cp)2Cl2 with NCS- in acetonitrile have been used to assess the solvation of the complexes. The rate law for this reaction contains first-order and second-order terms. The effect of addition of water or toluene to the main medium on the rate constant is reported. The binuclear complexes of d6 -metal ions with Tt-acceptor bridging ligands, like mononuclear complexes of the first group, also exhibit charge transfer spectra. Absorption occurs at rather lower energy and shows higher solvent sensitivities than mononuclear analogues. The majority of the complexes are relatively unstable. The rate of decomposition of the pyrazine carboxylate bridged [(en)2Co(pyzCOO)Fe(CN)5] anion, which follows intramolecular electron transfer, has been measured in binary aqueous solvent media. Its rate constant is markedly solvent dependent; no correlation with Marcus-Hush theory is observed.

Ultramarine is a blue pigment, formula ideally Na7.5A16 S1 6024S4.5 manufactured by Reckitt's Colours Ltd. at a rate of >10,000 tonnes per annum. The structure is based on a sodalite cage and the pigment is manufactured from kaolin, sulphur, sodium carbonate and minor ingredients, in furnaces with small surface area to volume ratios. To simulate industrial furnacing while examining a sample by PXRD (Powder X-Ray Diffraction) a novel 'Birkbeck Cell' was developed for use in a Guinier-Lenng camera. This cell is based on a stainless steel former with mica windows, and together with a gas rinsing system this arrangement produced the first time-resolved PXRD study of ultramarine formation: kaolinite is first separately calcined to the amorphous phase metakaolinite, to which the sulphur and sodium carbonate are added; in the second part of the furnace cycle sulphur and sodium carbonate react to form a sodium polysulphide, with metakaolinite later reacting with sodium salts to form a carnegieite, which then combines with the sodium polysulphides to form the initial ultramarine lattice ('primary ultramarine') ; in the latter part of the furnacing an 'oxidation' stage forms blue ultramarine and sodium sulphate is produced as a by-product. These results are supported by differential thermal analysis and thermogravimetric analysis; model furnacing; room temperature PXRD studies of various components and stages in the process; visible/uv spectrophotometry and electron microscopy. The structure of ultramarine was refined by Rietveld analysis of the neutron powder diffraction data and showed that the aluminium and silicon are not .OW0 ordered, the space group is 143m , the sodium ions lie just off the six-fold faces and the S 3 - group is in the centre of the cage, in a disordered arrangement. This analysis is supported by magic-angle spinning nuclear magnetic resonance, PXRD and the current literature on other spectroscopic methods. Finally the role of minor ingredients is examined and initial experiments to indicate possible alternative manufacturing methods are described.

This project concerned the basic chemistry of VD, Vm and FeD (iJ because of interest in the role of vanadium and iron in the electron-transfer processes catalysed by the nitrogenases, and (iiJ to try to rationalise the fragmented data available on the chemistry of low-oxidation-state vanadium and its reactions with iron(II) compounds. In order to increase the range of FeD materials available for reaction with VD, the dinuclear complex [{FeCI(tmeda)h{Jt-Cl)2] and the mononuclear [FeCI2(tmeda)2] (tmeda = N,N,N',N'-tetramethylethylenediamine) were synthesised and characterised by chemical and physical methods including X-ray diffraction. The reaction between vanadium(II) or iron(II) compounds, such as [MCI2(tmeda)z], and chloride-abstracting agents (e.g. M~SiI or NaBPh4) afforded trinuclear ionic complexes containing [M3Cl3Y2(LL)3]+ , where M = FeDor VD, Y = chloride and LL = bidentate amine or phosphine; complexes containing Y = methoxide and M = yD were isolated from methanol solutions. The planar {M3CI3} core is highly stable and remains intact during substitution of the axial Y groups and the neutral ligands. Mixed clusters containing both vanadium(II) and iron(II) can also apparently be synthesised, but the similarity of the metal radii in oxidation state II makes characterisation by X-ray diffraction analysis difficult. Attempts to produce yD_ or ym -bridging N2 compounds containing the ligand 2- [(N,N-dimethylamino)methyl]ferrocenyl (L) were not successful. In order to obtain additional information on the reactivity of L towards early transition metals, the cyclopentadienyltitanium (IV) complexes [Cp2Ti(L)CI] and [CpTiLxCl3.J (x = 1-3) were prepared. X-ray diffraction analyses of [Cp2Ti(L)CI] and [CpTi(L)CIJ have shown that L can be monodentate or bidentate, depending on steric constraints about the metal atom. The complex [CpTi(L)(L')] has also been synthesised; L' is a tridentate ligand apparently generated upon heating by intramolecular C-H activation of a methyl substituent on one of the tertiary amino groups of [CpTi(L)3], followed by elimination of neutral [(N,N-dimethylamino)methyl] ferrocene. The complexity of this system and the formation oftrinuclear vanadium(II) complexes possibly account for some of our difficulties in understanding vanadium-dinitrogen chemistry.

Transfer chemical potential trends have been determined from solubility measurements for uncharged encapsulated and semi-encapsulated iron(II) complexes, and for series of ?-diketonate metal complexes, in water-alcohol and water- dimethyl sulphoxide mixtures. These solubilities were obtained by spectrophotometry and atomic absorption spectrometry. The transfer chemical potentials are discussed in terms of ligand periphery and solvent nature. Reactivities for base hydrolysis of series of iron(II) diimine complexes, containing diazabutadiene, pyridine- derived Schiff base, terdentate, linear hexadentate, tripod and encapsulating cage ligands, in aqueous and aqueous-dimethyl sulphoxide mixtures have been determined, in order to examine second-order rate constants for base hydrolysis and their relation to ligand structure. Correlations between rate constants and respective electrode potentials have been considered for a series of diazabutadiene and pyridine-containing Schiff base complexes. Solvent effects on second-order rate constants for base hydrolysis of two iron (II) diimine complexes have been analysed in terms of initial state and transition state contributions. The effects of a2+ fluoro-substituted cosolvent on reactivity of [Fe (gei) 3] is reported and compared with those of analogous alcohols. Dependences of wavenumbers of maximum absorption for the lowest energy metal to ligand charge-transfer band of ternary iron (II) cyanide diimine complexes have been reported in series of binary aqueous solvent mixtures. The v max values for Fe (CN)2 ( phen) in non-aqueous solvents have examined in relation to Reichardt ET(30) values and solvent acceptor numbers, and the versatility of the complex as a probe of solvent polarity discussed. The v max values for Fe (CN) 2 (bipy) 2 in various hydroxylic media and hydroxylic-aqueous mixtures have been reported, and the usefulness of this complex as a probe for solvation trends for these media examined. The solvatochromic behaviour for Ti(Cp)2 (NCS)2, [W(CN) 6 (bipy)]2- and [W0(CN)3(bipy)2] in various non-aqueous solvents is reported, and the solvent sensitivities of these are complexes compared with those of ternary iron(II) cyanide diimine complexes.

The U.V. and laser induced photolysis of noble-gas/fluorine mixtures have been studied at -196C. The U.V. photolysis of krypton/fluorine and xenon/fluorine mixtures for 12h gives approximately a 30% yield of KrF2 and XeF2 respectively. Whilst photolysis with an argon ion laser gives comparable yields after only 30 minutes. Two temperature dependent phases of KrF2 were observed. Laser photolysis of oxygen/fluorine mixtures at -196C gives O4F2 and O2F2 and of UF5/F2 mixtures gives UF6. The photolysis of noble-gas /fluorine mixtures with added Lewis acids were also examined. A 1:1:2 mixture of fluorine, krypton and MF5 (M= As, Sb, I), photolysed at -196C using either U.V. or argon ion laser radiation also gives KrF2. There is no evidence of reaction with MF5 at -196C. Warming of the resultant mixtures affords Kr2F3+SbF6, a- and b- KrF+Sb2F11-, a-KrF+AsF6-, KrF+As2F11 and KrF2.nIF5 (n=1-3) at various temperatures which have been identified by Raman Spectroscopy. Investigations of reactions involving fluorine atoms, produced from elemental fluorine by the catalytic method, were made. Reactions involving krypton/fluorine and xenon/fluorine mixtures gave KrF2, XeF2 and XeF4 respectively. Also in this work an attempt was made to prepare a possible (Xe-I) containing species by the reaction between Xe2+Sb2F11- with iodine. Further investigations need to be carried out to clarify the results obtained.

No description available.

No description available.

No description available.

No description available.

No description available.