No description available.

No description available.

This thesis describes the design, optimisation and shipboard deployment of a flow injection - chemiluminescence (FI-CL) technique for the determination of cobalt (Co) and manganese (Mn) in seawater. Chapter One presents an overview of the marine environment and the biogeochemistry of Co and Mn. Current analytical methods for the determination of Co and Mn in natural waters are also reviewed. Chapter Two reports reagent clean-up techniques and the synthesis of an 8- hydroxyquinoline resin used for in-line matrix elimination and preconcentration. The resin is also characterised in terms of its chelating ability for the transition metals and the earth alkaline metals. A new column design is also presented. Chapter Three details the optimisation of a FI-CL system for the determination of Co in seawater. The method described is based on a new chemistry whereby CL emission is produced by oxidation of pyrogallol with hydrogen peroxide in alkaline medium in the presence of CTAB and MeOH. Chapter Four details the optimisation of a FI-CL system for the determination of Mn in seawater. The method chosen involved the luminous oxidation of 7,7,8,8- tetracyanoquinodimethane (TCNQ) by dissolved O2. The weak chemiluminescence of TCNQ is effectively sensitised by Eosin Y in DDAB. In Chapter Five the application of the FI-CL method to the shipboard determination of Co in the western North Sea is presented together with results from the determination of Mn in the western North Sea samples after the cruise. Co and Mn profiles are shown for all the geographical area investigated. The data from an entire tidal cycle of the Humber are also shown. Chapter Six presents the results of an intercomparison exercise. Co and Mn have been measured with different analytical techniques: FI-CL, AdCSV, and ICP-MS. The method developed for Co has been adapted in order to measure the concentration of Co in samples from the Scheldt estuary with an integrated luminometer at the Universite Libre de Bruxelles.

No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves 100-102. / viii, 102 l graphs, tables

Cobalt oxynitride films formed by magnetron sputter deposition of a Co target in N2 or NH3 plasma or, alternatively, by NH3 plasma nitridation of a Co film deposited on Si(100), show a divergence of properties arising from (a) N and O interactions for N and O atoms bonded to each other or through a common metal center and (b) the oxophilicity of the metal center itself. Core and valence band X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and plane wave density functional theory (DFT) calculations have been used to probe chemical and electronic interactions of nitrogen-rich cobalt oxynitride CoO1-xNx (x > 0.7) films. DFT-based calculations supervised by the Cundari group show the zinc blende (ZB) structure is found to be energetically favored over the rocksalt (RS) structure for x > ~ 0.2, with an energy minimum observed in the ZB structure for x ~ 0.8 - 0.9. There is also agreement with experiment for core level binding energies obtained for DFT calculations based on the ZB structure and this forms the basis of a predictive model for understanding how N and O interactions impact the electronic and catalytic properties of these materials. Vanadium oxynitride films were deposited in a mixture of O2/Ar/N2 environments on α-Al2O3(0001) or SiO2/Si(100) substrates to obtain films with varied N/O stoichiometries via magnetron sputter deposition using a vanadium target. Films deposited on the Al2O3(0001) substrates generally, though not always, exhibited a (111) orientation, which is consistent with a rock salt structure. The enhancement of the surface properties of vanadium oxynitride was explored to improve its catalytic properties.

The new Co(III) carbonate complexes [Co(uns-penp)(O₂CO)]ClO₄�H₂O and [Co(trpyn)(O₂CO)]ClO₄, containing tripodal tetraamine ligands, have been synthesised and characterised by microanalysis, �H, ��C and ⁵⁹Co NMR, mass spectrometry (MS) and UV-vis spectroscopy. In addition, the ⁵⁹Co NMR spectra have been obtained for two series of [Co(N₄)(O₂CO)]⁺ complexes containing aliphatic (N₄ = tren, baep, abap, trpn) and pyridyl (N₄ = tpa, pmea, pmap, tepa) tripodal tetraamine ligands and the complex [Co(dppa)(O₂CO)]⁺. The ⁵⁹Co NMR signal increases as [Delta] decreases, indicating there is less electron density at the Co(III) nucleus as the metal-ligand orbital overlap becomes poorer. A linear relationship was found to exist between the [Delta] for the individual complexes and their ⁵⁹Co NMR chemical shifts which follows the relationship: [Delta] = 29 174 + -0.89363 x [delta](⁵⁹Co) For the two series of [Co(N₄)(O₂CO)]+ complexes, plots of the magnetogyric ratio (γ) and [lambda][max] have y-intercepts that do not accurately correspond to the magnetogyric ratio of the bare cobalt nucleus (γ₀(Co)). This is due to the deviation of the complexes from pure octahedral symmetry. A fluxional process in the complex [Co(pmea)(O₂CO)]⁺ was investigated using variable temperate (VT) NMR. This was found to involve the inversion of a six-membered chelate ring about a pseudo mirror plane with a [Delta]G[double dagger] of 58 kJ mol⁻� at 25 �C. Mass spectra have been obtained for all the [Co(N₄)(O₂CO)]⁺ complexes, and these show a common fragmentation pattern for all the complexes except [Co(trpn)(O₂CO)]⁺, where CO₂ is lost from the molecular ion to give a [Co(N₄)O]⁺ adduct. Single crystal X-ray structural analyses were performed on [Co(abap)(O₂CO)]ClO₄ (orthorhombic, Pca2₁, a = 15.9744(11) Å, b = 8.6200(6) Å, c = 21.8568(15) Å, α = β = γ = 90�, Z = 8, R1 = 0.0350, wR2 = 0.0902), [Co(trpn)(O₂CO)]ClO₄�H₂O (monoclinic, P2₁/c, a = 11.9510(19) Å, b = 12.0740(19) Å, c = 12.917(2) Å, β = 117.56(4)�, α = γ = 90�, Z = 4, R1 = 0.0476, wR2 = 0.1188), [Co(tpa)(O₂CO)]ClO₄�2H₂O (triclinic, P-1, a = 16.2298(5) Å, b = 17.2291(5) Å, c = 17.3393(5) Å, α = 106.760(1)�, β = 92.809(1)�, γ = 108.004(1)�, Z = 8, R1 = 0.0349, wR2 = 0.0799), [Co(uns-penp)(O₂CO)]ClO₄�H₂O (triclinic, P-1, a = 6.7544(3) Å, b = 11.5523(5) Å, c = 12.3201(6) Å, α = 73.397(2)�, β = 89.749(2)�, γ = 84.551(2), Z = 2, R1 = 0.0277, wR2 = 0.0842) and [Co(trpyn)(O₂CO)]ClO₄ (monoclinic, P2₁/n, a = 12.2777(5) Å, b = 11.9322(4) Å, c = 27.9622(11) Å, β = 100.082(2)�, α = γ = 90�, Z = 8, R1 = 0.0435, wR2 = 0.1130). Rates of acid hydrolysis of [Co(N₄)(O₂CO)]⁺ (N₄ = baep, abap, trpn, tpa, pmea, pmap, tepa, uns-penp, dppa, trpyn, Me₃-tpa) complexes were measured by stopped flow or UV-vis spectroscopy (I = 1.0 mol L⁻�). The product of acid hydrolysis of [Co(pmea)(O₂CO)]⁺ has been indentified by X-ray crystallography as [Co(pmea)(OH₂)₂]�⁺ (triclinic, P-1, a = 9.7065(5) Å, b = 15.5645(8) Å, c = 11.5740(5) Å, α = 84.660(1)�, β = 123.255(1)�, γ = 104.283(1)�, Z = 2, R1 = 0.0402, wR2 = 0.1009). The acid hydrolysis reactions of the [Co(N₄)(O₂CO)]⁺ complexes containing aliphatic (N₄ = baep, abap, trpn) tripodal tetraamine ligands and [Co(tpa)(O₂CO)]⁺ and [Co(Me₃-tpa)(O₂CO)]⁺ have been investigated over the range [H₃O⁺] = 0.10 - 1.0 mol L⁻� Three processes were observed for the hydrolysis of [Co(baep)(O₂CO)]⁺, [Co(abap)(O₂CO)]⁺ and [Co(trpn)(O₂CO)]⁺ at all [H₃O⁺]. The first and second processes were thought to be [H₃O⁺] dependent, while the third was fit to a first order exponential decay and was [H₃O⁺] independent (k[obs] ~ 4.2 x 10⁻� s⁻� for [Co(baep)(O₂CO)]⁺, 3.8 x 10⁻� s⁻� for [Co(abap)(O₂CO)]⁺ and 3.5 x 10⁻� s⁻� for [Co(trpn)(O₂CO)]⁺). However, none of the processes could be confidently assigned to a step in the acid hydrolysis mechanism. The data obtained from the studies of [Co(tpa)(O₂CO)]⁺ and [Co(Me₃-tpa)(O₂CO)]⁺ showed a single first order [H₃O⁺] dependent process which was fit to the following expression: k[obs] = (k₁K[H₃O]⁺)/(1 + K[H₃O]⁺ This gave k₁ = 5.8 x 10⁻⁴ � 2.3 x 10⁻⁴ s⁻� and K = 0.13 � 0.06 L mol⁻� for [Co(tpa)(O₂CO)]⁺ at 25 �C and k₁ = 6.0 x 10⁻⁵ � 2.0 x 10⁻⁶ s⁻� and K = 0.38 � 0.02 L mol⁻� for [Co(Me₃-tpa)(O₂CO)]⁺ at 50 �C. Both values of K indicate that protonation of chelated carbonate is far from complete at [H₃O⁺] = 1.0 mol L⁻�. Comparative rates of acid hydrolysis at [H₃O⁺] = 6.0 mol L⁻� were obtained for the complexes [Co(tpa)(O₂CO)]⁺ (k[obs] = 1.79 x 10⁻� s⁻�, 25 �C), [Co(pmea)(O₂CO)]⁺ (k[obs] = 1.8 x 10⁻⁵ s⁻�, 25 �C), [Co(pmap)(O₂CO)]⁺ (k[obs] = 2.5 x 10⁻⁵ s⁻�, 50 �C), [Co(tepa)(O₂CO)]⁺ (k[obs] = 4.3 x 10⁻⁵ s⁻�, 25 �C) and [Co(trpyn)(O₂CO)]⁺ (k[obs] = 1.3 x 10⁻⁴ s⁻�, 50 �C) and at [H₃O⁺] = 1.0 mol L⁻� for the complexes [Co(uns-penp)(O₂CO)]⁺ (k[obs] = 2.9 x 10⁻� s⁻�, 25 �C) and [Co(dppa)(O₂CO)]⁺ (k[obs] = 2.7 x 10⁻⁴ s⁻�, 25 �C). The vast differences in the rates of acid hydrolysis can be rationalised on a steric basis. Bulkier ancillary ligands impede the direct protonation of an endo oxygen atom, or the transfer of a proton from the exo to an endo oxygen atom. The chelated bicarbonate complex [Co(trpyn)(O₂COH)]ZnCl₄�3H₂O has been synthesised and characterised by microanalysis and X-ray crystallography (orthorhombic, Pbca, a = 18.1820(66) Å, b = 14.7256(44) Å, c = 19.6344(68) Å, α = β = γ = 90�, Z = 8, R1 = 0.0435, wR2 = 0.1130). The first products of direct metallion of coordinated carbonate, under both acidic and neutral conditions, have been isolated and characterised by microanalysis and IR spectroscopy. The X-ray crystal structures of the bimetallic complexes [Co(Me-tpa)O₂COZnCl₃]�H₂O (triclinic, P-1, a = 8.262(1) Å, b = 11.290(1) Å, c = 13.766(2) Å, α = 95.314(4)�, β = 103.160(4)�, γ = 107.071(5)�, Z = 2, R1 = 0.0382, wR2 = 0.0940) and [Co(pmea)O₂COZnCl₃]�H₂O (triclinic, P-1, a = 8.2916(7) Å, b = 11.0999(11) Å, c = 14.0994(13) Å, α = 8.2916(7)�, β = 102.607(4)�, γ = 108.600(4)�, Z = 2, R1 = 0.0347, wR2 = 0.0770), and the trimetallic complex [(Co(trpyn)(O₂CO))₂Zn(H₂O)̀₄](ZnCl₄)₂�3H₂O (monoclinic, P2₁/c, a = 20.9734(17) Å, b = 17.3712(12) Å, c = 15.7635(13) Å, β = 111.376(4)�, α = γ = 90�, Z = 4, R1 = 0.0235, wR2 = 0.0517) have been obtained. In addition, the X-ray crystal structures of the complexes [Co(trpyn)(O₂CO)](Zn(OH)₂Cl₃)�4H₂O (triclinic, P-1, a = 7.4962(7) Å, b = 13.4019(11) Å, c = 13.6887(11) Å, α = 74.631(4)�, β = 82.893(4)�, γ = 82.324(4)�, Z = 2, R1 = 0.0268, wR2 = 0.0638) and [Co(tepa)(O₂CO)]₂(ZnCl₄)�3H₂O (triclinic, P-1, a = 9.9250(10) Å, b = 15.5561(13) Å, c = 15.8730(16) Å, α = 89.545(4)�, β = 85.019(5)�, γ = 72.714(4)�, Z = 2, R1 = 0.0291, wR2 = 0.0722) were obtained. These two complexes were synthesised under analogous conditions to the bi- and trimetallic complexes. However, in these cases metallation of chelated carbonate did not occur. DFT calculations have been used to calculate the relative energies of pairs of geometric isomers of [Co(N₄)(O₂CO)]⁺ complexes (N₄ = baep, abap, pmea, pmap, dppa, Me-tpa, Me₂-tpa). In all cases, except that of [Co(Me-tpa)(O₂CO)]⁺, the calculations correctly predict that the experimentally observed isomer is lower in energy. An electronic study on two series of [Co(N₄)(O₂CO)]⁺ complexes containing pyridyl (N₄ = tpa, pmea, pmap, tepa) and Me-pyridyl (N₄ = tpa, Me-tpa, Me₂-tpa, Me₃-tpa) tripodal tetraamine ligands correctly reproduces the observed trends in ⁵⁹Co NMR chemical shift and [Delta] values. A molecular orbital analysis of the two series of complexes shows that there is no significant difference between the highest energy occupied orbitals with the largest contribution from the coordinated oxygen atoms. Bond decomposition analyses of the two series of complexes indicate that there is also no difference in total bond energies. These results indicate that there is no electronic explanation for the large differences in reactivity towards acid that is observed experimentally. The first mononuclear complex containing chelated hydrogen phosphate, [Co(pmea)(O₂PO₂H)]ClO₄, has been synthesised and characterised using microanalysis, �H, ��C, ��P and ⁵⁹Co NMR, UV-vis spectroscopy and X-ray crystallography (monoclinic, P2₁/c, a = 8.7017(17) Å, b = 27.639(5) Å, c = 9.586(2) Å, β = 112.818(9)�, α = γ = 90�, Z = 4, R1 = 0.0443, wR2 = 0.1076). The X-ray crystal structure of [Co(pmeaH)(OH₂)Cl₂](CoCl₄)�H₂O (orthorhombic, P2₁2₁2₁, a = 12.6354(3) Å, b = 12.6354(3) Å, c = 15.8261(11) Å, α = β = γ = 90�, Z = 4, R1 = 0.0397, wR2 = 0.0954), in which the pmea ligand is coordinated in a hypodentate fashion, was also obtained. [Co(pmeaH)(OH₂)Cl₂](CoCl₄)�H₂O is thought to be an impurity in crude samples of [Co(pmea)Cl₂]Cl. The pK[a] of [Co(pmea)(O₂PO₂H)]⁺ was determined to be 4.99 � 0.02 by potentiometric titration. A ring inversion fluxional process, analogous to that observed for [Co(pmea)(O₂CO)]⁺, was found by VT-NMR to have a [Delta]G[double dagger] of 60 kJ mol⁻� at 35 �C. A ��P NMR spectrum, taken after the solution was left standing for approximately three hours, showed evidence of cleavage of the hydrogen phosphate chelate via a bimetallic hydrolysis mechanism. Attempts were also made to synthesise Co(III) complexes containing chelated phosphate ester ligands (monomethyl phosphate and monophenyl phosphate), with pmea as the ancillary ligand. ��P NMR spectra of the crude samples indicate that the monomethyl phosphate moiety is chelated to Co(III) (��P [delta] = 21.05 ppm). However, it is unclear whether the monophenyl phosphate is chelated or bridging between two Co(III) ions (��P [delta] = 14.36 ppm).

Producing nickel and cobalt metal by high pressure acid leaching (HPAL) of nickel laterites is becoming one of Australia's largest mineral processing industries. However, the background chemical information for this process, including the fundamental physicochemical properties of acidic metal sulphate leachate solutions, is not well known. In order to improve the efficiency of current and future HPAL plants, high quality physicochemical and thermodynamic data will be necessary. This thesis reports measurements on the densities and heat capacities of nickel and cobalt sulphate solutions and their mixtures along with detailed studies of the nature of the species present and the thermodynamics of their interconversions. Densities and heat capacities of nickel and cobalt sulphate and perchlorate solutions and their ternary mixtures were measured using a vibrating tube densimeter and a flow microcalorimeter respectively. These data were used to calculate the apparent molal volumes and heat capacities of these solutions. Standard partial molal quantities were then obtained by appropriate extrapolation procedures, along with the volume and heat capacity changes of ion pair formation. A comparison has been made between experimental densities and heat capacities with those predicted by Young's rule. Good agreement was obtained except when the degree of complexation varied significantly in the mixturesThe various ion pair species in nickel and cobalt sulphate solutions, along with those of magnesium sulphate (which is a major impurity in HPAL leachates), were reinvestigated by dielectric relaxation spectroscopy. Doubly solvent separated ion pairs, solvent shared ion pairs and contact ion pairs were shown to exist simultaneously in solution and their concentrations were determined from dilute to near-saturated concentrations. Evidence for the possible existence of a triple ion, M2SO4 2+, was also obtained in highly concentrated solutions. The equilibrium constants of the stepwise reactions and the effective hydration numbers of ions and ion pairs were also calculated. The heats of complexation of nickel(II) and cobalt(II) sulphate were determined at different ionic strengths in sodium perchlorate media by titration calorimetry. These data were fitted to a specific ion interaction model to obtain the standard state values. The corresponding entropies of complexation were calculated and were found to be the major contributor to the stability of the complexes.

Zugl.: Atlanta, Georgia, USA, Georgia Inst. of Technology, Diss., 2007

Thesis (M.Sc.) -- University of Adelaide, Dept of Physical and Inorganic Chemistry, 1973.