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Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005.
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| Format: | Thesis |
| Language: | af_ZA |
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2008
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| _version_ | 1867613812658536448 |
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| access_status_str | Open Access |
| author | Stander, Elzet |
| author2 | Raubenheimer, H. G. |
| author_browse | Raubenheimer, H. G. Stander, Elzet |
| author_facet | Raubenheimer, H. G. Stander, Elzet |
| author_sort | Stander, Elzet |
| collection | Thesis |
| description | Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/2851 |
| institution | Stellenbosch University (South Africa) |
| language | af_ZA |
| last_indexed | 2026-06-10T12:42:05.565Z |
| 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:10019.1/2851 Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse Stander, Elzet Raubenheimer, H. G. Cronje, S. University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. Carbenes Methylene compounds Complex compounds Metal complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. This study comprises the preparation and characterisation of completely new Fischer-type carbene complexes of chromium and tungsten by deprotonation of (CO)5M=C(NMe2)(Me), (CO)5M=C(OMe)(Me) or (CO)5M=C(NMe2)C≡CH, and subsequent treatment of the formed anion with a variety of reagents, including reactive metal complexes. The deprotonation of the termodynamically stable complexes, (CO)5M=C(NMe2)(Me) (M = Cr or W) followed by reaction with the sulfonium salt, [Me2(MeS)S][BF4], yielded not only the expected products (CO)5M=C(NMe2)CH2SCH3, but also thioether complexes, (CO)5MS(CH3)2, disulfinated complexes (CO)5M=C(NMe2)CH(SCH3)2, S-bridged dinuclear compounds (CO)5M=C(NMe2)CH2S(CH3)M(CO)5, as well as the unique fourmembered- C,S-chelate carbene complexes (CO)4Cr=C(NMe2)CH(SCH3)SCH3 and (CO)4M=C(NMe2)CH2SCH3. Crystal structure determinations of (CO)5W=C(NMe2)CH(SCH3)2, (CO)5Cr=C(NMe2)CH2S(CH3)Cr(CO)5, (CO)4M=C(NMe2)CH2SCH3 (M = Cr, W) and (CO)4Cr=C(NMe2)CH(SCH3)SCH3 were successfully performed. The latter tetracarbonyl complexes have Cr-S bonding distances of 2.4531(9) and 2.4517(5) Å and a W-S distance of 2.577(1) Å. These relatively weak bonds contribute to the short M-C(O)-distances trans to it. The formed four membered chelate rings are essentially planar. The deprotonation of (CO)5Cr=C(NMe2)(Me) and sequential reaction with sulphur and CF3SO3Me does not yield the expected product, (CO)5Cr=C(NMe2)CH2SCH3, but (CO)5CrS=C(NMe2)CH3 resulting from a sulphur insertion was isolated. A single crystal structure determination of the latter complex shows a normal thione carbene complex. The reaction of methyl(methoxy)carbenepentacarbonylchromium(0) and the tungsten analogue with n-BuLi, followed by reaction with [Me2(MeS)S][BF4], afforded unexpected complexes via an unusual addition dissimilar to the above mentioned reactions of dimethylaminocarbene complexes. The formation of the products, (CO)5M=C(OMe)[CH=C(Me)NH(Me)] and (CO)4M=C(OMe)[C(SMe)=C(Me)NH(Me)] (M = Cr, W) can be ascribed to the influence of the heteroatom, oxygen, as well as the presence of acetonitrile in the sulfonium salt reagent [Me2(MeS)S][BF4]. An unusual alkylation by Me+ is also affected. The X-ray crystallographic structure determination of the complexes show hydrogen bonding between the alkoxy oxygen atoms and the protons on the nitrogen atoms. The latter four membered C,S-chelates show bonding distances and angles similar to these of the previously mentioned four membered chelates. Deprotonation of the alkynyl carbene complexes, (CO)5M=C(NMe2)C≡CH (M = Cr, W), with n-BuLi and subsequent reaction with PPh3AuX (X = Cl, NO3), initially afford the β-transmetalated products (CO)5M=C(NMe2)C≡CAuPPh3. In solution (CH2Cl2) the product isomerises through metal migration to Ph3PAuC(NMe2)=C=C=W(CO)5. The conversion was followed by means of 1H-NMR-spectroscopy and it appears that two first order reactions take place consecutively. 2008-07-31T08:27:31Z 2010-06-01T09:00:00Z 2008-07-31T08:27:31Z 2010-06-01T09:00:00Z 2005-03 Thesis http://hdl.handle.net/10019.1/2851 af_ZA application/pdf |
| spellingShingle | Carbenes Methylene compounds Complex compounds Metal complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science Stander, Elzet Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title | Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title_full | Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title_fullStr | Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title_full_unstemmed | Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title_short | Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse |
| title_sort | nuwe reaksies van gedeprotoneerde fischer tipe karbeenkomplekse |
| topic | Carbenes Methylene compounds Complex compounds Metal complexes Dissertations -- Chemistry Theses -- Chemistry Chemistry and Polymer Science |
| url | http://hdl.handle.net/10019.1/2851 |
| work_keys_str_mv | AT standerelzet nuwereaksiesvangedeprotoneerdefischertipekarbeenkomplekse |