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Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study
Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2008
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| _version_ | 1867613970903334912 |
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| access_status_str | Open Access |
| author | Van der Molen, Lynndal |
| author2 | Koch, Klaus R. |
| author_browse | Koch, Klaus R. Van der Molen, Lynndal |
| author_facet | Koch, Klaus R. Van der Molen, Lynndal |
| author_sort | Van der Molen, Lynndal |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/2605 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:36.436Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2008 |
| publishDateRange | 2008 |
| publishDateSort | 2008 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/2605 Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study Van der Molen, Lynndal Koch, Klaus R. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Chelate metathesis Palladium(II) High-performance liquid chromatography Platinum(II) Nickel(II) chelates Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. N,N-dialkyl-N-acyl(aroyl)thiourea ligands form stable chelated complexes in a cis configuration with the platinum group metals. Such chelated complexes are generally considered substitutionally “inert” in solution, however, it was found that cis-bis(N,Ndialkyl- N-acyl(aroyl)thioureato)M(II) complexes (M = Ni(II), Pd(II) or Pt(II)) readily undergo facile chelate metathesis reactions in solution at room temperature. Upon mixing two different parent complexes, a mixed-ligand product formed in solution, with an equilibrium, or steady state, between the two parent complexes and the mixed-ligand product being attained after a period of time: M(LA)2 + M(LB)2 M(LA)(LB). All three complexes remained in solution even with a ten-fold excess of one parent complex. The presence of the mixed-ligand products in solution was confirmed by liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectra and a crystal structure of the mixed-ligand complex cis-Pd(L3-S,O)(L4-S,O). Though a number of attempts were made, it was not possible to either isolate or synthesise the mixed-ligand complexes exclusively. The equilibrium distribution and the rate of the metathesis reaction were influenced by a number of factors, including the central metal ion, the substituents on the complexed ligands and the reaction medium. In addition to these, a number of other factors, some unexpected, also played a role in the rate of the reaction. Initial concentration of the parent complexes, the age of the solutions upon mixing and the presence of impurities or additives all contributed to the overall rate of reaction. The results from these rate studies highlighted the necessity for extensively purified compounds. In addition to chelate metathesis reactions, the exchange between a cis-Pd(L-S,O)2 complex and an unbound HL ligand in solution was also investigated. Again, even with an excess of unbound ligand, all three possible complexes were present in solution. It has been shown previously that these complexes undergo a photoinduced cis-trans isomerisation under intense light, and it has been proposed that the reverse trans-cis process, which occurs in the dark, may be a metathesis reaction. In light of this, the relationship between these chelate metathesis reactions and the reverse trans-cis reaction was briefly investigated. Though the metathesis reactions were a general phenomenon in the Ni(II), Pd(II) and Pt(II) complexes of the aforementioned ligands, the experiments focused mainly on the cis-Pd(L-S,O)2 complexes due to the favourable timescales of their metathesis reactions. The primary technique to observe these reactions was reversed-phase high-performance liquid chromatography (rp-HPLC). The timescales involved in the cis-Pd(L-S,O)2 metathesis reactions as well as the stability of the Pd(II) complexes under the HPLC conditions made this technique ideal. 2008-05-09T10:16:01Z 2010-06-01T08:53:28Z 2008-05-09T10:16:01Z 2010-06-01T08:53:28Z 2008-03 Thesis http://hdl.handle.net/10019.1/2605 en_ZA Stellenbosch University 2909668 bytes application/pdf application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Chelate metathesis Palladium(II) High-performance liquid chromatography Platinum(II) Nickel(II) chelates Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Van der Molen, Lynndal Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title | Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title_full | Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title_fullStr | Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title_full_unstemmed | Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title_short | Spontaneous metathesis of bis-chelated PdII(L-S,O)2 complexes in solution : a rp-HPLC study |
| title_sort | spontaneous metathesis of bis chelated pdii l s o 2 complexes in solution a rp hplc study |
| topic | Chelate metathesis Palladium(II) High-performance liquid chromatography Platinum(II) Nickel(II) chelates Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science |
| url | http://hdl.handle.net/10019.1/2605 |
| work_keys_str_mv | AT vandermolenlynndal spontaneousmetathesisofbischelatedpdiilso2complexesinsolutionarphplcstudy |