The chemistry of the tantalum dinitrogen complex ([NPN]Ta)₂ (μ-H)₂ (μ-η¹:η²-N₂ )Ta-[NPN], 1, (where [NPN] represents the acyclic tridentate ligand [(PhNSiMe₂ CH₂ )₂ -PPh]² -), with primary alkenes, group IV and V metallocene complexes, and GaCp* is explored. The reaction of 1 with 1-pentene and 1-hexene occurs via olefin-insertion into the metal-hydride bond to give two new complexes, ([NPN]Ta(CH₂)₄CH₃)₂ (μ-η¹:η¹-N₂ ), 10, and ([NPN]Ta(CH₂ )₅CH₃)₂ (μ-η¹:η¹-N₂ ), 11, which were characterized using NMR spectroscopy. The solid-state structure of 11 was established and revealed that N₂ has been transformed into a bridging end-on mode. In contrast to its G symmetry in solution, the solid-state structure of 11 is C, symmetric; a VT-NMR study was performed and showed that 11 exists as an equilibrium between two isomers in solution: a C, symmetric isomer 11A,which is the predominant isomer at room temperature, and a C, symmetric isomer 11B,which is the minor isomer. The reactivity of 1 with group IV and V metallocenes was investigated. The reaction of 1 with Cp₂ Hf(PMe₃)(η²-Me₃SiCCSiMe₃) produces [N(μ-P=N)N]Ta(μ-H)₂(μ-N(Hf-Cp₂ ))Ta[NPN], 14, in which N₂ is cleaved and new Hf-N and P=N bonds have formed. The reaction of 1 with group V metallocene hydrides Cp₂ MH₃ (M Nb, Ta) was also attempted however these complexes do not react with 1. The reaction of 1 with GaCp* produces a new complex, [NPN]Ta(μ-N(GaCp*))Ta(=NPμ)[NPIA,-N], 18, which was characterized using NMR spectroscopy. Complex 18 decomposes over several days in solution, and one product of decomposition that was isolated was [(PhNH)(NPμ-N)Ta]₂ , 19. The solid-state structure of 19 showed that the [NPN] ligand was cleaved at the N-Si bond, similar to that observed for the reaction of 1 with 9-BBN and HB(C₆H₅)₂ . A mechanism for the formation of complexes 18 and 19 is proposed. / Science, Faculty of / Chemistry, Department of / Graduate

Studies were carried out on nitrifying capacities of duff mull and raw humus soils of the Douglas-fir forest. For this purpose, perfusion apparatuses were set up according to the technique described by I.J. Audus (8) with certain modifications which seemed to improve considerably the application of this apparatus for soil studies. Certain changes were introduced into the method as given by H. Lees and J.H. Quastell (54). The quantitative estimations of ammonia and nitrates were made by colorimetric method using phenoldisulphonic and NaOH-EDTA solution for nitrates and Nessler's reagent for ammonium determinations. Soils used for this experiment were tested for total organic matter and total nitrogen. From the results obtained, the most striking difference between the raw humus (mor) and duff mull was observed in the total absence of nitrification in all samples of mor and the comparatively vigorous nitrification in all samples of mull. There was further confirmation that the acidic condition of mor humus alone is not the limiting factor in nitrification in such forest soils. In duff mull, nitrification occurred over a wide range of pH. In raw humus, after adjusting pH to 6.5 and 7.0 and inoculating with actively nitrifying garden soil, no nitrification was observed. It was of interest to note that nitrification occurred only when mor soil was subjected to complete drying or steam sterilization before being inoculated. This phenomenon might indicate the presence of some inhibitory action against nitrifying organisms. This inhibitory effect is typical of raw humus (mor) but lacking when it is sterilized by steam. In all leachates of raw humus some ammonium was always detected. As far as could be determined, nitrifying duff mull soils have failed to show any significant seasonal variation. It was difficult to establish any correlation between total nitrogen of soils, their carbon/nitrogen ratio, and their capacity for nitrification. It is understood that nitrates, are not the only source of nitrogen for the metabolism of forest trees; nevertheless, nitrates should be regarded as an important ecological factor in the evaluation of forest sites. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate

Verticillium albo-atrum R. and B. isolates were separated into four strain groups based on morphological type. All isolates were tested for pathogenicity toward tomato, and an attempt was made to relate pathogenicity to morphological type. Since structural and functional differences in plants and animals are believed to be invariably associated with chemical differences, a survey of the nitrogenous constituents of the isolates was made in an attempt to relate any differences to morphological or pathologic strains. The alcohol-soluble extract from the mycelium of each isolate was investigated chromatographically for amino acids, amines, amides and peptides. The amino acids found were the same for all isolates. These were aspartic acid, glutamic acid, lysine, histidine, isoleucine, serine, valine, proline, methionine, ∝ alanine, tyrosine, threonine, glycine and one unidentified neutral compound, A. No amines, amides or peptides were detected. The amino acids, amines, amides and peptides of the ∝, β and Ȣ strains of Colletotricum lindemuthianum (Sacc. and Magn. ) Bri. and Gav. were isolated and identified using the techniques of paper chromatography for the purpose of comparison with Verticillium albo-atrum. The three Colletotricum strains contained the same amino acids as the Verticillium isolates with the exception of unknown A which was replaced by another unknown, B, common to all three Colletotricum strains indicating a definite species difference. Strain differences apparently do not occur in these two organisms in the groups of compounds studied. The effect of aeration, age of mycelium, pH of medium and carbon source on the qualitative amino acid content of isolate V3 were studied. These environmental conditions had no qualitative effect on the amino acids of the isolate. The free nucleotides of the acid-soluble extract of six representative isolates were studied using the technique of anion-exchange chromatography. Nucleotides isolated from all isolates and tentatively identified were guanosine monophosphate, guanosine diphosphate, guanosine triphosphate, cyt-idine diphosphate, uridine monophosphate, uridine diphosphate, uridine triphosphate and adenosine diphosphate. No other nucleotides were isolated. The above results indicated that if chemical dif-ferences do exist between strains, as postulated, they do not occur, In these two organisms, among the nitrogenous compounds studied, but must occur In some other class of compounds not studied in this investigation. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate

Anaerobic ammonium oxidation (anammox) is a pathway that has been known for almost 2 decades, but few studies have investigated its importance in natural groundwaters. This thesis investigated the presence of anammox cells and the groundwater geochemistry of 2 sites (Elmira and Putnam) in southwestern Ontario where groundwaters are contaminated with high levels of nitrate and ammonium. Fluorescence in situ hybridization (FISH) was used to quantify the relative abundance of anammox cells in these waters. Our results showed that anammox cells could be detected in many wells at both sites and that their relative abundance varied between 0.45 and 4.81 % at the Putnam site, whereas it ranged between 0.8 to 8.4 % at the Elmira site. These values are within the same range as those obtained for marine and freshwater environments where anammox cells have been detected. In addition, indirect observations point to the fact that N cycling at the 2 sites might be linked to Fe and Mn reduction, but additional experiments are needed. In summary, our results corroborate the findings of N-labeled microcosm experiments which demonstrated that anammox was an important pathway of N cycling in those groundwaters and molecular analyses that detected important anammox organisms at the same sites.

Two similar greenhouse experiments wore carried out to observe the effects of 2 forms of nitrogen fertilizer, (nitrate and urea), each at 5 rates, (0, 30, 60, 90, and 120 lb N per acre), on cranberry plants, (Vaccinium macrocarpon Ait. cv. McFarlin). In the first experiment, treatments were applied to cuttings which had been rooted for a short time whereas in the second experiment, cuttings which had been rooted for 7 months as well as cuttings which had just been rooted were used. Growth measurements and foliar mineral analyses were carried out on shoots collected from actively growing plants 2 and 16 weeks after differential treatment in the first experiment and 14 weeks after treatment in the second experiment. In both experiments, N fertilization soon after rooting enhanced vegetative growth. Greater vegetative growth was obtained with nitrate in the first experiment but with urea in the second. Analysis of variance indicated that treatments which increased growth also increased foliar N and decreased foliar P, Fe, and Ca. In the first experiment, growth measurements were linearly correlated with foliar Mg or Mn or both in the first harvest, but in the second harvest, correlations were with foliar N, P, and K content. In the second experiment, cuttings which had been rooted for some time initiated more shoots and leaves, but did not respond to N treatments. / Land and Food Systems, Faculty of / Graduate

It is known that the functional activity of the nervous system is associated with ammonia formation and that the administration of ammonium salts to experimental animals produces convulsions. Mechanisms, therefore, that control ammonia metabolism in the brain are of importance for brain cell function. The presence of ammonia utilizing mechanisms in the brain maintains the low free cerebral ammonia levels found in vivo. There is, however, a rapid formation of ammonia in the brain on the death of the animal and a further liberation of ammonia takes place when isolated brain cortex is incubated aerobically in the absence of glucose. Studies of these and other aspects of ammonia metabolism form the subject matter of this thesis. The estimation of ammonia in these studies is based on a modification of the diffusion technique of Conway. Ammonia and amino acid analyses have been carried out using the Beckman amino acid analyzer. The rapid rate of cerebral ammonia formation that takes place when the brain is removed from the animal is partially arrested by trichloracetic acid (TCA), presumably by the inactivation of cerebral enzymes. Our results rule out the possibility that glutamine, glutamate, taurine and ATP are significant contributors to the initial or pre-incubation levels of ammonia and the evidence favors the involvement of TCA-insoluble components as precursors of such ammonia. In the presence of glucose the pre-incubation levels of amino acids of cerebral cortex slices of the rat are maintained during subsequent aerobic incubation at 37°C for one hour. In the absence of glucose, however, we have found marked changes in the pre-incubation levels of amino acids of cerebral cortex slices under these experimental conditions. A considerable rise of ammonia also occurs in the absence of glucose and this can be largely accounted for by a net loss of –NH₂-groups of the amino acid pools of brain slices. The significant fall in the cerebral levels of glutamate and glutamine under these conditions indicates that for short periods of incubation (one hour), these amino acids may serve as major sources of ammonia formation by respiring brain cortex slices. Our findings of a marked suppression of ammonia formation by cerebral cortex slices incubated for one hour either anaerobically, or aerobically, in a glucose-free medium in the presence of amytal, D-glutamate or α-methylglutamate, implicate the oxidative deamination of cerebral glutamate as a major mechanism for ammonia liberation. D-glutamate also acts by inhibiting the hydrolysis of glutamine. In the presence of glucose aerobic incubation with 2, 4-dinitrophenol, iodoacetate, malonate, hydroxylamine or D-glutamate, increases the rate of ammonia formation by cerebral cortex slices. This is doubtless due to diminished activity of cerebral glutamine synthetase required for ammonia fixation to occur. We find that the level of ammonia in the brain tissue itself is not markedly affected by the presence of absence of glucose. The increased quantity of ammonia formed by cerebral cortex slices in the absence of glucose is found largely in the incubation medium. This fact points to the formation of ammonia in specific compartment(s), and the retention of ammonia within such compartment(s) up to a certain level. Above this level there is efflux of ammonia into the incubation medium. Such a conclusion helps to explain the apparent high concentration ratio (tissue:medium) of NH₄⁺ obtained either aerobically (viz. 42) or anaerobically (viz. 12) at the end of one hour incubation in the presence of glucose. There is some accumulation of NH₄⁺ ions in rat brain cortex slices against a concentration gradient. Our finding that ouabain stimulates ammonia formation in respiring cerebral cortex slices is in accord with the fact that ouabain inhibits the utilization-of NH₄⁺ for the biosynthesis of glutamine, presumably by affecting the transport of NH₄⁺ to the site of glutamine synthesis. Ouabain has no effect on the cerebral glutaminase of the rat. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

Nitrogen oxide trifluoride was prepared in trace quantities by the reaction of nitric oxide and fluorine. Low, but improved yields were obtained when nitrosyl fluoride and fluorine were heated together at 220°. It was found that (NO)₂2NiF₆ was formed by the reaction of the walls of the Monel reaction vessels, with nitrosyl fluoride, and fluorine, and that pyrolysis of this salt (in 70 p.s.i. fluorine at 350°) gave the new compound in good yield. The reactions of platinum and iridium hexafluoride with nitrosyl fluoride were investigated as routes to ONF₃. Nitrogen oxide trifluoride was colourless in the solid, liquid, and gaseous phases, melting at -161° and boiling at -87.5°. The vapour pressure was determined over the range -128° to -78°. The empirical formula was established by elemental analysis, and by determination of its molecular weight. The structural formula ONF₃ was established from the ¹⁹F n.m.r., and the infrared spectrum of the compound. Nitrogen oxide trifluoride was found to be only moderately reactive. There was no evidence that ONF₃ could be protonated by strong acids. A 1:1 adduct was formed with AsF₅. The chemical behaviour and infrared spectrum of ONF3,AsF₅ was consistent with the formulation ONF₂⁺AsF₆⁻. The empirical formula of (NO)₂^NiF₆ was established by elemental analysis. Its infrared spectrum, and magnetic susceptibility showed that it contained the (NO)⁺ and (NiF₆)²⁻ ions, and a low spin d⁶ arrangement for Ni(IV). The X-ray powder diffraction patterns of (NO)₂NiF₆ could be indexed on the basis of a hexagonal unit cell a = 5.524 Å, c = 5.097 Å, except for five diffuse lines that varied in intensity from sample to sample. Weissenberg (h k 0, h k 1,h k 2, h k 3) photographs showed two sets of reflections. One sharp strong set that could be indexed on the basis of the same hexagonal cell as the lines of the powder photograph, and a weak diffuse set of reflections that together with the strong reflections could be indexed on the hexagonal unit cell, a = 4x5.524, c = 5.097 Å. A structure determination was carried out using the strong sharp set of reflections. The diffraction data were consistent with various models, but the most likely model consisted of (NiF₆)²⁻ groups with the fluorine atoms in a regular octahedron around the nickel atom and the Ni-F bond distance equal to 1.76 Å. The N-O bond distance was very short, 0.88Å, and had associated with it regions of electron density normal to the axis defined by the nitrogen and oxygen atoms. A similar situation for the O2⁺ ion in O₂PtF₆ was reported by Ibers and Hamilton.(108) At 200° chlorine pentafluoride and iridium hexafluoride reacted to give small quantities of a yellow compound which was characterised as ClF₂⁺IrF₆⁻ from elemental analysis, magnetic susceptibility measurements, and its infrared spectrum. A structural determination was attempted from single crystal X-ray data. Preliminary results suggest that the iridium atoms form an ab face centred array, and the chlorine atoms are situated almost in the centre of the square pyramidal holes defined by the iridium atoms. / Arts, Faculty of / Philosophy, Department of / Graduate

Nitrogen fertilization of grassland and forest range in British Columbia is examined as a practical means of increasing productivity. Trials were undertaken at several altitudes and responses were studied in fenced and unfenced plots over a period of two years. Four clipping times, three rates of ammonium nitrate application and two times of application were the major treatments at most sites. Information on climate and soil was also obtained and clipped forage was analyzed for nitrogen. Increases in dry matter yield and combined nitrogen levels obtained on all sites despite the marked mid-season limitation of soil moisture; responses to autumn fertilization were evident in early growth in the spring following application; responses to spring application were delayed. Response to fertilizer has continued to be marked in the second year after application. Understory vegetation of the forest range responded to fertilization at first but by the second year, it appears, overstory vegetation (trees) was responding to the detriment of understory yield. / Land and Food Systems, Faculty of / Graduate

The reactions: [formulae omitted] have been studied here in a discharge flow system. Using two temperatures, the rate constant for wall deactivation was found to be 3.8 x 10² exp [fomula omitted] sec⁻¹. It was concluded that the deactivation was not diffusion controlled as previously suggested but controlled by the surface deactivation process on the walls. The rate constant for production of O₂(¹Σg＊) was found to be 6.7 x 10⁴ exp [formula omitted] litres mole⁻¹sec⁻¹, in reasonable agreement with the room temperature value determined by Arnold. An upper limit of 1.6 x 10⁴ litres mole⁻¹sec⁻¹ was obtained for the rate constant of the reaction: N + O₂ (¹Δg ) → NO + 0 showing that the reaction is considerably slower than expected from comparison with the analogous reaction of ground state oxygen. This is rationalized by showing that the two reactions require different transition states. Whilst studying the above reaction several surface catalysed glows from molecular nitrogen and nitric oxide were seen. These glows were found to require O₂ (¹Δg) for their production and not atomic oxygen as previously thought. Several qualitative and spectroscopic experiments were performed and in the light of the information gained various possible mechanisms are discussed. / Science, Faculty of / Chemistry, Department of / Graduate

Nitrogen (N) fertilizer management in wheat (Triticum aestivum L.) can impact grain yield and protein. Develping strategies that improve N efficiency are needed to optimize wheat production in North Dakota. Field experiments were conducted to evaluate N stabilizers, N rate, N placement and application timing on grain yield and protein of winter and spring wheat. The timing of N release from a polymer coated urea (ESN) was also studied. Nitrogen stabilizers improved N efficency in some environments but not all. Deeper placement of urea helped reduce N losses. The closer that N fertilizer was applied to the date it was utilized by wheat usually increased protein. Nitrogen release from ESN was gradual over several months offering potential protection against N losses from a fall or spring applicaton.