Thesis (M. Sc.)--University of Hong Kong, 1970. / Mimeographed.

Asymmetric nitrene transfer reactions via metalloradical catalysis (MRC) with azides has attracted research interest because of its fundamental and practical importance. The resulting nitrogen-containing units are recurrent motifs in biologically important molecules and can serve as versatile precursors in organic synthesis. The [Co(D2-Por*)] have emerged as a new class of catalysts for asymmetric aziridination and C-H amination. These metalloradical catalysts have been shown to be highly effective for the asymmetric intermolecular aziridination of a broad scope of substrates with different classes of azides with excellent to good enantioselectivity. The intramolecular C-H amination utilizing various azides can allow for the construction of diverse nitrogen containing heterocyclic compounds.

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published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy

No description available.

No description available.

We have observed the electronic transitions within the ('4)T(,1g) ground state of Co('2+) in MgO by Raman spectroscopy. We identified the (GAMMA)(,6g) (--->) (GAMMA)(,8g)('1) transition at 305 cm('-1) and the (GAMMA)(,6g )(--->)(, )(GAMMA)(,8g)('2) transition at 930 cm('-1); the (GAMMA)(,6g )(--->)(, )(GAMMA)(,7g) transition is not seen and is lost in the two-phonon band. We also observed an impurity induced vibration mode at 280 cm('-1), in resonance with the acoustic phonon branches at the surface of the Brillouin zone. The position of the electronic levels cannot be explained by crystal field theory, with the spin-orbit interaction to second-order included. We have calculated the effect of a dynamical Jahn-Teller interaction and have shown, for the first time, the necessity to include the coupling to the T(,2g) mode, in addition to the coupling to the E(,g) mode, although Co('2+) in MgO is a weak Jahn-Teller system. / We also used Raman spectroscopy to observe the vibrational modes of (beta)-In(,2)Se(,2). We observed, for the first time, the layer to layer shear mode(E(,2g)('2)), at 19 cm('-1). The position of this peak and the others, at 42(E(,1g)('1)), 117(A(,1g)('1)), 179(E(,2g)('1)), 181(E(,1g)('2)) and 231 cm('-1)(A(,1g)('2)), follows the trend of the vibrational spectra of (beta)-Ga(,2)S(,2) and of (beta)-Ga(,2)Se(,2) {65}. Using the linear chain model, we calculated the shear force constants and deduced the position of the doublet (E(,2g)('1) and E(,1g)('2)) with very good agreement with the experimental values.

Lithium cobalt oxide was synthesized by solid-state reactions and SPRAY-DRY method. Its investigation of the formation were perform of lithium and cobalt acetate, lithium and cobalt citrate, LiOH and Co(NO3)2· 6H2O mixtures in high-temperatures. Their formation was analyzed and with the help of the X-ray diffraction the structure of the products of the solid-state reactions was determined. The thermal processes, that take place during the synthesis, were analyzed with the help of differential-thermal analysis.

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