Complexes of the general formula M(X-SALDAPE) and M(X-SALDAPS) formed by the reaction of substituted salicylaldehydes and bis(3,3'-aminopropyl)ether or bis(3,3'-aminopropyl)sulfide with nickel(II) and cobalt(II) have been isolated. The complexes have been characterized by elemental analysis, mass spectra, infrared spectra, magnetic susceptibility measurements, and ultraviolet-visible-near infrared spectra. In the solid state the nickel(II) complexes, Ni(X-SALDAPE) and Ni(X-SALDAPS), where X = H, 5-Br, 3-(CH₃)₂CH, or 3-CH₃O, are speculated as pseudo-square planar or weak low-spin five-coordinate structures. The complexes exhibit anomalous magnetic behavior explained in terms of a spin state isomerism between singlet and triplet spin states. In a non-coordinating solvent, the nickel complexes are pseudo-square planar losing all five-coordinate structural features due to salvation. When dissolved in a coordinating solvent, the complexes are high-spin pseudo-octahedral. The cobalt(II) complexes, Co(H-SALDAPE) and Co(X-SALDAPS) where X = H, or 3-(CH₃)₂CH, were found to be high-spin pseudo-tetrahedral in the solid state with magnetic moments of approximately 3.4 B.M. The olive green nickel complexes are stable to air and moisture. The brownish cobalt complexes are stable as dry solids, but very easily oxidized when wet. / Master of Science

Call number: LD2668 .T4 1985 J665 / Master of Science

No description available.

Zn(_x)Co(_2-x)GeO(_4) materials were prepared and the variation in structure with composition was investigated using XED, SEM and EDX analysis. Limited series of solid solution were identified at both ends of the compositional range. D C electrical measurements were carried out to characterize the variation in the resistivity of the materials with humidity. Resistivities of the order of 10(^8) Ω m were observed in dry conditions, decreasing by 4 to 5 orders of magnitude with increasing humidity. Resistivity was not found to vary greatly with composition. Resistivity was temperature dependent, increasing by 1 to 2 orders of magnitude for a 70 C decrease in temperature. A C impedance measurements were performed to gain an understanding of the mechanism of the humidity dependent conductivity. At low frequencies impedance was found to be independent of frequency and humidity dependent. At high frequencies impedance was found to be inversely proportional to frequency and independent of humidity. The break point frequency was also humidity dependent and an increase in the impedance indicated inductive-type behaviour. Complex plane representation of the impedance gave a distorted semicircle at high frequencies and a low frequency tail. At high humidities the tail appears as a straight line, inclined at approximately 45 . At medium levels of humidity a distinctive loop is apparent at the intersection between the semicircle and the tail, corresponding to the inductive behaviour indicated at the break point frequency. The impedance response was modelled by an equivalent circuit consisting of various ideal and constant phase (dispersive) elements. The proposed mechanism of humidity-dependent conductivity is due to chemisorption and physisorption of water vapour from the atmosphere at the surface of the material, It is suggested that conduction occurs by hopping of protons between cheraisorbed hydroxyl groups at low humidities, by diffusion of H(_3)O(^+) ions between the hydroxyl groups at intermediate humidities and by hopping of protons between physisorbed H(_3)O(^+) ions (Grotthus Chain reaction) at high humidities.

Magnetic properties of cobalt clusters (20 N 200) were studied in molecular beams. The magnetization of cobalt clusters is studied at a broad range of temperatures, magnetic fields and clusters sizes. It is shown that the agnetization of ferromagnetic clusters in a cluster beam can be understood as an adiabatic process using the avoided crossing theory. Besides the ground state that bears magnetic moment of about 2 Bohr magneton per atom, an excited state that has 1 Bohr magneton per atom was discovered for every cobalt cluster observed. The energy separations between the two states was investigated by photo-ionization experiments. The ionization threshold shows that the energy gap between the two states is on the order of 0.1 eV for small clusters (N 100) and vanishes for larger clusters. Experiments also show that the polarizability of the excited state is lower than that of the ground state, which indicates a significant electronic tructure difference between the two states. Two states are also found for iron clusters (20 N 200) for which the magnetic moments per atom are about 3 Bohr magneton for the ground state and 1 Bohr magneton for the excited states. This explains the fractional magnetic moments as well as the local magnetic order observed above the Curie temperatures for iron group ferromagnets. Further experiments show two states for manganese clusters for which the ground state has magnetic moment of 1 Bohr magneton per atom in about the same size range. This suggests that the two states are a universal phenomenon of 3d transition metal clusters, which originate from the interaction between 3d and 4s electrons.

No description available.

Thesis (Ph. D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 52-10, Section: B, page: 5229. Supervisor: M.J. McGlinchey.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 216-224).

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2008. / Includes bibliographical references.

M.Sc. (Chemistry) / Pyrazolyl and imidazolyl-based compounds were used as ligands in the synthesis of cobalt(II) and zinc(II) complexes. These ligands were prepared using literature methods.