Gold complexes obtained from gold ylide preparations

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dc.contributor.advisor Raubenheimer, H.G.
dc.contributor.advisor Cronje, S.
dc.contributor.author Coetzee, Karolien
dc.contributor.other Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. en
dc.date.accessioned 2012-06-04T12:47:07Z
dc.date.available 2012-06-04T12:47:07Z
dc.date.issued 2005-04
dc.identifier.uri http://hdl.handle.net/10019.1/21206
dc.description Thesis (MSc)--University of Stellenbosch, 2005. en_ZA
dc.description.abstract ENGLISH ABSTRACT: This investigation comprised the synthesis and characterisation of new Au(I) phosphonium ylide complexes and other compounds formed during coordination reactions. These complexes could exploit the synergism between two pharmacologically active substances (gold complex unit and phosphorus ylide) to furnish an even more active substance. Four phosphonium salts were prepared, [C6H5CH2PPh3]Br (1), [Ph3P(CH2)3PPh3]Br2 (2a), p-[{Ph3PCH2}2C6H4]Br2 (3a) and m- [{Ph3PCH2}2C6H4]Br2 (4a), by reacting PPh3 with the corresponding alkylbromides. The 13C and 1H NMR spectra of the compounds 1 – 4a indicated that many of the nuclei are magnetically inequivalent. The aromatic units in PPh3 are normally identical, but multiple, overlapping signals proved that the corresponding ortho, meta and para carbon and proton nuclei are in magnetically different environments from each other. Single crystal structures of salts 3a and 4a were determined. Different methods were followed to deprotonate the phosphonium salts to afford the corresponding ylides and to coordinate the ylides to gold precursor compounds. Most of the reactions yielded inseparable mixtures of products and pure compounds could not be isolated in large enough quantities for characterisation by all physical methods. Sufficient crystals for structure determination by X-ray diffraction were obtained. The product mixtures were characterised by 1H, 13C and 31P NMR spectroscopy and mass spectrometry. Characteristic downfield chemical shift changes after coordination of the ylides to Au(I) were observed for the carbon and phosphorus nuclei, while the protons displayed upfield shifts. Reaction of (C6F5)Au(tht) with the salts 1 – 4a, and subsequent deprotonation yielded the gold(I) ylide complexes [C6H5CH(AuC6F5)PPh3] (5), [{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), and m- [{Ph3PCH(AuC6F5)}2C6H4] (9). The crystal and molecular structures of compounds 5 and 9 were determined. Deprotonation of 4a with n-BuLi, followed by reaction with (C6F5)Au(tht) yielded complexes 9 and [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). The crystal structure of compound 10 was determined. Two aurocyclic compounds, [μ- {(Ph3PCH)2CH2}2Au2][BF4]2 (12) and [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) were synthesised by deprotonating salts 2b and 3b with n-BuLi and subsequently reacting the corresponding bisylides with ClAu(tht). Reaction procedures in which Ag2O was used as deprotonating agent for the phosphonium salts 2a, 3a and 4a, yielded mixtures of products. Single crystals of complexes m-[Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) and [(C6F5)2Au][(Ph3PCH2)2C6H4] (16) were isolated from the reaction mixtures and subjected to X-ray crystal structure determination. The molecular structure of 15 exhibited unusual aurophilic interactions and represents the first example of a linear gold chain in which the gold···gold distances systematically alternate between 3.13Å, 3.31Å and 3.20Å. Salt 2b was reacted with Ph3PAu(acac) to afford the desired compound, [{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), along with [CH3C(O)C(AuPPh3)2C(O)CH3] (17) and some byproducts. Compound 17 was characterised by single crystal Xray diffraction. The fluorobiphenylgold(I) complexes, 4,4’-[(AuPPh3)2C12F8] (21) and 2,2’- [(AuPPh3)2C12F8] (22) were synthesised by reaction of ClAuPPh3 with the lithiated 2,2’-dibromooctafluorobiphenyl and 4,4’-dibromooctafluorobiphenyl respectively. The molecular structure of 21 revealed that one of the C–Au–P bond angles deviates from linearity by 12.5°, probably as a result of π-stacking of the tetrafluorophenyl rings and steric requirements of the bulky PPh3 units. The other C–Au–P bond angle is linear [177.9(3)°]. en_ZA
dc.description.abstract AFRIKAANSE OPSOMMING: Hierdie studie behels die sintese en karakterisering van nuwe fosfoniumylied goud(I)-komplekse en ander verbindings wat gedurende koördinasiereaksies vorm. Sulke komplekse kan sinergisme tussen twee farmakologies-aktiewe entiteite (goud(I) en fosfoniumylied) om ʼn meer aktiewe verbinding te vorm meebring. Vier fosfoniumsoute is berei, [C6H5CH2PPh3]Br (1), [Ph3P(CH2)3PPh3]Br2 (2a), p- [{Ph3PCH2}2C6H4]Br2 (3a) en m-[{Ph3PCH2}2C6H4]Br2 (4a), deur PPh3 met die ooreenstemmende alkielbromiedes te reageer. Die 13C- en 1H- KMR-spektra van dié verbindings toon dat ʼn aantal kerne in aromatiese ringe magneties onekwivalent is. Normaalweg is die koolstowwe in PPh3-eenhede ekwivalent, maar meervoudige, oorvleuelende pieke het nou getoon dat die ooreenstemmende orto-, meta- en para-koolstof sowel as die ooreenstemmende protonkerne in verskillende magnetiese omgewings voorkom. Die kristalstrukture van die soute 3a en 4a hierbo is met behulp van X-straal tegnieke bepaal. Verskillende metodes is gevolg om die fosfoniumsoute te deprotoneer na die ooreenstemmende yliede en om die yliede dan aan goud-bevattende uitgangstowwe te probeer koördineer. Die meeste reaksies het nie-skeibare mengsels gevorm en enkelprodukte kon nie in groot genoeg konsentrasies geïsoleer word om hulle afsonderlik te karakteriseer nie. Kristalle vir X-straal kristalstruktuur bepalings is verkry. Die produkmengsels is gekarakteriseer met behulp van 1H-, 13C- en 31P- KMR-spektroskopie en massaspektrometrie. Karakteristieke veranderinge in chemiese verskuiwings na laer veldsterktes vir die koolstof en fosfor kerne is waargeneem na koördinasie van die yliede aan Au(I), terwyl die protone na höer veldsterktes verskuif het. Die reaksie tussen (C6F5)Au(tht) (tetrahidrotiofeen) en soute 1 – 4a gevolg deur deprotonering, vorm die goud-yliedkomplekse [C6H5CH(AuC6F5)PPh3] (5), [{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), en m- [{Ph3PCH(AuC6F5)}2C6H4] (9). Die kristalstrukture van komplekse 5 en 9 het al die molekulêre interaksies daarin blootgelê. Deprotonering van 4a met n-BuLi, gevolg deur reaksie met (C6F5)Au(tht) lewer komplekse 9 en [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). Die kristal- en molekulêre struktuuur van kompleks 10 is bepaal. Twee aurosikliese verbindings, [μ- {(Ph3PCH)2CH2}2Au2][BF4]2 (12) en [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) is gesintetiseer deur gedeprotoneerde bisyliede verkry van 2b en 3b met substitusie van tht aan die ClAu-eenheid te koördineer. Reaksieprosedures waarin Ag2O vir deprotonering van die fosfoniumsoute 2a, 3a en 4a gebruik is, het tot mengsels van produkte aanleiding gegee. Enkelkristalle van komplekse [Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) en [(C6F5)2Au][(Ph3PCH2)2C6H4] (16) is geïsoleer uit die reaksies en kristalstruktuurbepalings is uitgevoer. Die molekulere struktuur van 15 toon ongewone aurofiliese interaksies en verteenwoordig die eerste voorbeeld van ʼn linieêre goudketting; met goud···goud afstande wat sistematies varieër tussen 3.13Å, 3.31Å en 3.20Å. Sout 2b is met Ph3PAu(acac) gereageer om die gewenste produk, [{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), saam met [CH3C(O)C(AuPPh3)2C(O)CH3] (17) en ander byprodukte te vorm. Verbinding 17 is as enkelkristalle Xstraalkristallografies gekarakteriseer. Die fluorobifeniel goud(I)-komplekse, 4,4’-[(AuPPh3)2C12F8] (21) en 2,2’- [(AuPPh3)2C12F8] (22), is gesintetiseer deur koördinasie van AuPPh3 aan die gelitieërde 2,2’-dibromooktafluorobifeniel en 4,4’-dibromooktafluorobifeniel respektiewelik. Die molekulere struktuur van 21 het getoon dat een van die C-Au- P bindingshoeke met 12.5º afwyk van 180º, waarskynlik as gevolg van π- interaksie van die tetrafluorofenielringe en die steriese vereistes van die groot PPh3-eenhede. Die ander C-Au-P bindingshoek is linieêr [177.9(3)°]. af
dc.format.extent 136 leaves : ill.
dc.language.iso en_ZA en_ZA
dc.publisher Stellenbosch : Stellenbosch University
dc.subject Ylides en_ZA
dc.subject Complex compounds en_ZA
dc.subject Organophosphorus compounds en_ZA
dc.subject Theses -- Chemistry en_ZA
dc.subject Dissertations -- Chemistry en_ZA
dc.title Gold complexes obtained from gold ylide preparations en_ZA
dc.type Thesis en_ZA
dc.rights.holder Stellenbosch University en_ZA


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