Thesis (MSc)--University of Stellenbosch, 2005. / 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)°]. / 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)°].
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21206 |
| Date | 04 1900 |
| Creators | Coetzee, Karolien |
| Contributors | Raubenheimer, H.G., Cronje, S., Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 136 leaves : ill. |
| Rights | Stellenbosch University |
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