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Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2008.
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| Format: | Thesis |
| Language: | en_ZA |
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2008
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| _version_ | 1867613923685957632 |
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| access_status_str | Open Access |
| author | Le Roux, Adele |
| author2 | Luckay, Robert C. |
| author_browse | Le Roux, Adele Luckay, Robert C. |
| author_facet | Luckay, Robert C. Le Roux, Adele |
| author_sort | Le Roux, Adele |
| collection | Thesis |
| description | Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2008. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/3111 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:51.865Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2008 |
| publishDateRange | 2008 |
| publishDateSort | 2008 |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/3111 Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively Le Roux, Adele Luckay, Robert C. Raubenheimer, H. G. University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. Polyoxometalates Metal complexes Ligands Sulphur-complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2008. In this study, the coordination of certain Group 6 and Group 10 & 11 metals to Odonor and S-donor ligands were investigated. For the most part, this involved the isolation of new Mo(VI) and W(VI) complexes. By using a distribution diagram that shows the dependence of the type of species in solution with pH, we attempted to crystallize new polyoxoanion species of the two metals. It was found that the products that crystallize are not necessarily dependant upon the relative concentrations of the species in solution, but rather on the effective packing of the crystal types that are prepared. During this study a unique W(VI) polyanion, [(CH3CH2)4N]2[W6O19] (4), was isolated. The Mo(VI) analogue of this compound as well as the dinuclear Mo(VI)-W(VI) complex have been reported previously, but a pure W(VI) compound of this type has not been successfully isolated yet. A new polymorph of a known dimolybdate, K2Mo2O7·H2O (1), was also crystallized, even though dimolybdate species do not generally occur in solution. This structure, although previously reported, shows some differences with the one in the literature, in particular large deviations in unit cell dimensions. Subsequently, as a second component of this study, a variety of carboxylates were coordinated to Mo(VI) and W(VI) species in an acidic medium. Two new complexes of Mo(VI) with these carboxylate ligands were isolated: [(CH3CH2)4N][MoO3(mal)]·H2O (5) (mal = malate) and Na6[Mo2O5(cit)2] (6) (cit = citrate). The ligands are two- and threefold deprotonated respectively and coordinate in a polydentate manner to the metal centra. The formation of compound 5 in solution has been known for many years, but the structure of this complex has not been determined in the solid state until now. Also, the tungsten analogue of compound 6 was reported years ago, but the Mo(VI) complex has not been crystallized before. Compounds 5 and 6 exhibit a 1:1 and 2:2 metal to ligand ratio respectively, and these ratios are quite rare in Mo(VI) crystal chemistry. Finally, the dimolybdate complex, [CH3)3N(CH2)6N(CH3)3][Mo2O7(cit)] (7), was isolated, and its structure determined and compared to the one in the literature. In the third part of this study, our attention shifted to the group 10 and 11 metals, platinum and gold. Attempts were made to coordinate unusual ligands with donor atoms P, Se and/or S to these metal centers. During this investigation, we isolated a unique Pt(IV) complex, PtCl2(S3C8H7)2 (9). The structure of this compound that was determined crystallographically involves the coordination of two identical R-SCS2 fragments to the metal ion forming four-membered chelate rings. No compounds of Pt and Au with the P-Se ligand, P3Se3(C(C6H5)3)3, could be isolated. However, a mixed valence compound of Au(I,III), [Au(I)Cl(S(CH2C6H5)2)][Au(III)Cl3(S(CH2C6H5)2] (8), could be isolated and characterized. In this compound Au exhibits two oxidation states, +1 and +3. Although the complex has been reported previously, the structure was not described fully, and we now unequivocally determined its crystal structure. The extended structure shows the formation of chains of alternating Au(I) and Au(III) centers with a separation of 5.610 Å. 2008-06-18T10:56:13Z 2010-06-01T09:06:34Z 2008-06-18T10:56:13Z 2010-06-01T09:06:34Z 2008-03 Thesis http://hdl.handle.net/10019.1/3111 en_ZA application/pdf |
| spellingShingle | Polyoxometalates Metal complexes Ligands Sulphur-complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Le Roux, Adele Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title | Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title_full | Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title_fullStr | Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title_full_unstemmed | Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title_short | Hard-hard and soft-soft coordination in complexes of Group 6 and Group 10 & 11 metals respectively |
| title_sort | hard hard and soft soft coordination in complexes of group 6 and group 10 11 metals respectively |
| topic | Polyoxometalates Metal complexes Ligands Sulphur-complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science |
| url | http://hdl.handle.net/10019.1/3111 |
| work_keys_str_mv | AT lerouxadele hardhardandsoftsoftcoordinationincomplexesofgroup6andgroup1011metalsrespectively |