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Synthesis and characterization of palladium complexes exhibiting hemilabile properties
Thesis (M.Sc.) -- University of Stellenbosch, 1998.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613875194560512 |
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| access_status_str | Open Access |
| author | Esterhuysen, Matthias Wilhelm |
| author2 | Raubenheimer, H. G. |
| author_browse | Esterhuysen, Matthias Wilhelm Raubenheimer, H. G. |
| author_facet | Raubenheimer, H. G. Esterhuysen, Matthias Wilhelm |
| author_sort | Esterhuysen, Matthias Wilhelm |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M.Sc.) -- University of Stellenbosch, 1998. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/51039 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:05.531Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/51039 Synthesis and characterization of palladium complexes exhibiting hemilabile properties Esterhuysen, Matthias Wilhelm Raubenheimer, H. G. Brull, R. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Organometallic compounds Organometallic chemistry Palladium Dissertations -- Chemistry Thesis (M.Sc.) -- University of Stellenbosch, 1998. This study comprises the preparation and characterization of various new neutral organometallic complexes of palladium containing hemilabile alkyl-/arylthioethercarboxylate and alkyl-/arylselenoethercarboxylate ligands. The main aim of this work is to develop novel catalysts that show activity in carbon-carbon linking reactions. By changing certain properties of the hemilabile ligands employed, the effects and importance that these properties have in the hemilability of the complexes and their catalytic activities could be studied. A series of complexes, each with a slightly different hemilabile ligand, was thus prepared and studied using this approach. Among the characteristics changed in order to study their effects on the hemilability of the complexes were the alkyl chain length of the ligand, the chalcogen donor atom in the potentially bidentate ligand and electronic and steric influences of a substituent on the donor atom. These aspects were studied with the aim of finding a possible correlation between the hemilability of these complexes and their catalytic activity in phenylacetylene oligomerization reactions. All the neutral palladium complexes prepared in this study were synthesized through a reaction in which trans-[Pd(C₆H₅)Cl(P(C₆H₅)₃)₂] (I) is reacted with the thallium salts of the various carboxylic acids of the ligands. These thallium alkyl-/arylthioether- and alkyl-/arylselenoethercarboxylates were prepared by the neutralization of the alkyl-/arylthioether- and alkyl-/arylselenoethercarboxylic acids of the ligands with thallium carbonate. During the synthesis of the complex the ligand binds to the palladium atom through the oxygen atom of the carboxylate and thallium chloride readily precipitates. In contrast to other complexes showing hemilabile properties that are synthesized with the potentially hemilabile ligand in a bidentate mode, these compounds were synthesized with their ligands bound monodentately. The bidentate species is then formed through a reversible intramolecular reaction in which the S or Se donor atoms in the hemilabile ligand coordinate to the palladium, under certain conditions, the displacement of a triphenylphosphine ligand from the complex. Equilibria of this intramolecular reaction type were studied in solution by direct ¹H NMR monitoring. Single crystal X-ray diffraction, furthermore, provided molecular structures of species on both sides of the hemilabile equilibrium with sulphur and selenium as donor atoms, thus concluseively proving the hemilabile charateristics of these ligands. The activation energies and the free energy changes were also be determined and were used in further describing the processes invlolved in the hemilabile equilibrium. Masters 2012-08-27T11:34:18Z 2012-08-27T11:34:18Z 1998 Thesis http://hdl.handle.net/10019.1/51039 en Stellenbosch University 180 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Organometallic compounds Organometallic chemistry Palladium Dissertations -- Chemistry Esterhuysen, Matthias Wilhelm Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title | Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title_full | Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title_fullStr | Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title_full_unstemmed | Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title_short | Synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| title_sort | synthesis and characterization of palladium complexes exhibiting hemilabile properties |
| topic | Organometallic compounds Organometallic chemistry Palladium Dissertations -- Chemistry |
| url | http://hdl.handle.net/10019.1/51039 |
| work_keys_str_mv | AT esterhuysenmatthiaswilhelm synthesisandcharacterizationofpalladiumcomplexesexhibitinghemilabileproperties |