This thesis describes investigations into the metal-mediated formation of nitrogen-carbon bonds from hydrazines and alkynes. Rh, Ir, Ru and Os metal complexes containing bidentate P,N- and N,N-donor ligands were all studied during the course of this work. A series of stereoisomers of metal complexes of general formula MCl2(PyP)2 (where M = Ru and Os, PyP = 1-(2-(diphenylphosphino)ethyl)pyrazole) (2.01-2.05) were synthesised. The isomerisation process of complexes 2.01-2.05 in solution was investigated. The ruthenium complex RuCl2(CO)(1-P-PyP)(2-P,N-PyP) (2.14), which contains one pendant PyP ligand bound through the P-donor ligand was synthesised, confirming the potential hemilability of the mixed P,N-donor ligand PyP. Chloride abstraction from the ruthenium complex trans,cis,cis-RuCl2(PyP)2 (2.01) was achieved using either a sodium or silver salt to yield the dimeric complexes of general formula [Ru(μ-Cl)(PyP)2]2[X]2 (where M = Ru, X = OSO2CF3 (2.06), BF4 (2.07), BPh4 (2.08), and BArF 2.09). [Os(μ-Cl)(PyP)2]2[BPh4]2 (2.10) was synthesised from sodium tetraphenylborate and trans,cis,cis-OsCl2(PyP)2 (2.04). The reactivity of dimeric complexes 2.06 and 2.08 towards substituted hydrazines was investigated. The methylhydrazine complex [Ru(PyP)2(NH2NHMe)][Cl][BPh4] (3.12) was synthesised. The methylhydrazine adduct of 3.12 binds to the metal centre in an end-on fashion via the NH2 group in solution, and in a bidentate fashion in the solid-state. This is the first reported example of a ruthenium complex containing a bidentate hydrazine ligand. The ruthenium-vinylidene complexes [RuCl(Me2PyP)2(=C=C(H)Ph)]BPh4 (4.15) and [RuCl(Me2PyP)2(=C=C(H)n-Bu)]BPh4 (4.16) (Me2PyP = 1-(2-(diphenylphosphino)ethyl)-3,5-dimethylpyrazole) were synthesised from trans,cis,cis-RuCl2(Me2PyP)2 (4.10) and the appropriate terminal alkyne. The reaction of alkynes with ruthenium complexes containing the PyP ligand was also investigated. Nitrogen-carbon bond formation was achieved through reaction of mono-substituted hydrazines with 4.06 and 4.07 to yield complexes of general formula [RuCl(1-P-Me2PyP)(2-P,N-Me2PyP)(2-N,C-(NH2N(R2)C(CH2R1)]BPh4 (where R1 = R2 = Ph (4.19), R1= Ph, R2 = Me (4.20), R1 = n-Bu, R2 = Ph, (4.21) or R1 = n-Bu, R2 = Me (4.22)). The mechanism of the formation of the stable metallocyclic complexes 4.19-4.22 was elucidated through studies of the reactivity of 4.15 towards a series of amines and hydrazines and relies on the labile nature of the N-donor of the P,N-donor ligand Me2PyP. A method for the synthesis of triflate complexes of rhodium Rh(PyP)(CO)(OSO2CF3) (5.13) and Rh(PyPhP)(CO)(OSO2CF3) (PyPhP = 1-(2-(diphenylphosphino)phenyl)pyrazole) (5.14) from rhodium chloride complexes was developed. The solid-state structure of rhodium triflate complex 5.14, which contained the more sterically rigid ligand PyPhP, exhibited a much greater distortion from the ideal square planar geometry than the rhodium analogue 5.13 which contains the PyP ligand. The triflate group of 5.13 and 5.14 was displaced by substituted hydrazines to yield new hydrazine complexes of rhodium. A series of Rh and Ir complexes with bidentate P,N- and N,N-donor ligands were found to catalyse the intermolecular hydroamination of alkynes with hydrazines. [Ir(bpm)(CO)2]BArF (6.08) was found to be the most efficient catalyst of those studies for this transformation, and was amongst the most efficient catalysts reported to date for this transformation. The influence of counter-ion was highly significant in the catalysed intermolecular hydroamination reaction. The substrate scope of the intermolecular hydroamination of alkynes with hydrazines was investigated using [Ir(bpm)(CO)2]BArF (6.08) as the catalyst.

No description available.

This thesis describes investigations into the metal-mediated formation of nitrogen-carbon bonds from hydrazines and alkynes. Rh, Ir, Ru and Os metal complexes containing bidentate P,N- and N,N-donor ligands were all studied during the course of this work. A series of stereoisomers of metal complexes of general formula MCl2(PyP)2 (where M = Ru and Os, PyP = 1-(2-(diphenylphosphino)ethyl)pyrazole) (2.01-2.05) were synthesised. The isomerisation process of complexes 2.01-2.05 in solution was investigated. The ruthenium complex RuCl2(CO)(1-P-PyP)(2-P,N-PyP) (2.14), which contains one pendant PyP ligand bound through the P-donor ligand was synthesised, confirming the potential hemilability of the mixed P,N-donor ligand PyP. Chloride abstraction from the ruthenium complex trans,cis,cis-RuCl2(PyP)2 (2.01) was achieved using either a sodium or silver salt to yield the dimeric complexes of general formula [Ru(μ-Cl)(PyP)2]2[X]2 (where M = Ru, X = OSO2CF3 (2.06), BF4 (2.07), BPh4 (2.08), and BArF 2.09). [Os(μ-Cl)(PyP)2]2[BPh4]2 (2.10) was synthesised from sodium tetraphenylborate and trans,cis,cis-OsCl2(PyP)2 (2.04). The reactivity of dimeric complexes 2.06 and 2.08 towards substituted hydrazines was investigated. The methylhydrazine complex [Ru(PyP)2(NH2NHMe)][Cl][BPh4] (3.12) was synthesised. The methylhydrazine adduct of 3.12 binds to the metal centre in an end-on fashion via the NH2 group in solution, and in a bidentate fashion in the solid-state. This is the first reported example of a ruthenium complex containing a bidentate hydrazine ligand. The ruthenium-vinylidene complexes [RuCl(Me2PyP)2(=C=C(H)Ph)]BPh4 (4.15) and [RuCl(Me2PyP)2(=C=C(H)n-Bu)]BPh4 (4.16) (Me2PyP = 1-(2-(diphenylphosphino)ethyl)-3,5-dimethylpyrazole) were synthesised from trans,cis,cis-RuCl2(Me2PyP)2 (4.10) and the appropriate terminal alkyne. The reaction of alkynes with ruthenium complexes containing the PyP ligand was also investigated. Nitrogen-carbon bond formation was achieved through reaction of mono-substituted hydrazines with 4.06 and 4.07 to yield complexes of general formula [RuCl(1-P-Me2PyP)(2-P,N-Me2PyP)(2-N,C-(NH2N(R2)C(CH2R1)]BPh4 (where R1 = R2 = Ph (4.19), R1= Ph, R2 = Me (4.20), R1 = n-Bu, R2 = Ph, (4.21) or R1 = n-Bu, R2 = Me (4.22)). The mechanism of the formation of the stable metallocyclic complexes 4.19-4.22 was elucidated through studies of the reactivity of 4.15 towards a series of amines and hydrazines and relies on the labile nature of the N-donor of the P,N-donor ligand Me2PyP. A method for the synthesis of triflate complexes of rhodium Rh(PyP)(CO)(OSO2CF3) (5.13) and Rh(PyPhP)(CO)(OSO2CF3) (PyPhP = 1-(2-(diphenylphosphino)phenyl)pyrazole) (5.14) from rhodium chloride complexes was developed. The solid-state structure of rhodium triflate complex 5.14, which contained the more sterically rigid ligand PyPhP, exhibited a much greater distortion from the ideal square planar geometry than the rhodium analogue 5.13 which contains the PyP ligand. The triflate group of 5.13 and 5.14 was displaced by substituted hydrazines to yield new hydrazine complexes of rhodium. A series of Rh and Ir complexes with bidentate P,N- and N,N-donor ligands were found to catalyse the intermolecular hydroamination of alkynes with hydrazines. [Ir(bpm)(CO)2]BArF (6.08) was found to be the most efficient catalyst of those studies for this transformation, and was amongst the most efficient catalysts reported to date for this transformation. The influence of counter-ion was highly significant in the catalysed intermolecular hydroamination reaction. The substrate scope of the intermolecular hydroamination of alkynes with hydrazines was investigated using [Ir(bpm)(CO)2]BArF (6.08) as the catalyst.

The system in which atmospheric nitrogen succumbs to enter Nature's cycle has a yet proven evasive with respect to the actual chemical reactions. At present several types of systems are proposed but their chemical makeup is practically unknown.

No description available.

No description available.

Hydrazine and monomethylhydrazine are widely used as propellants in aerospace and defense industries. However these chemicals are volatile, carcinogenic, and sensitive to impact, which impose serious threats during their usage. In this thesis, we have demonstrated two novel ways to immobilize hydrazine chemicals. In one approach hydrazine, monomethylhydrazine have been gelled using carbon dioxide. Chemical and structural properties of these gels are studied by NMR (1H, 15N, 13C), diffusion-ordered NMR spectroscopy, and Cryo-HRSEM. Thermal reversibility of these gels is also demonstrated. In another approach, hydrazine, monomethylhydrazine and 1,1-dimethylhydrazine are reacted with 5-methyltetrazole to form ionic liquids. Synthesis of novel tetrazole monomers and polymers, .and new method for encapsulating sodium azide have also reported in this thesis

Picosatellites are defined as satellites with a mass between 0.1 and 1kg (Miniaturized satellite). Picosatellites are typically designed to work together or function in formations (Miniaturized satellite). A specific type of Picosatellite known as CubeSats were introduced in 1999 and since then have increased in popularity so that there are now over 80 CubeSat programs around the world. CubeSats are defined as cubic units 10cm on each side and no more than 1kg in mass. CubeSats are required to conform to the CubeSat Standard created by California Polytechnic State University and Stanford University and be compatible with Cal Poly’s P-POD deployment system (Toorian, 2005). Some CubeSat uses include earth imaging, communications projects and various scientific experiments. CubeSats currently require attitude control and in the future, may require, maintaining a specific orbit, or changing orbit. With this ability many new activities may be possible for CubeSats. These activities could include rendezvous, vehicle inspection, formation flying and de-orbiting. For these activities to be possible, a high performance propulsion system is required. The goal of this thesis is to design and test an affordable, safe, and effective micro-propulsion system for CubeSats.

Dissertation (Ph.D.)--University of Stellenbosch, 1996. / Bibliography. Also available via the Internet.

No description available.