No description available.

No description available.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Two new potentially biodegradable aminopolycarboxylic acid ligands, iminodiglutaric acid tetra sodium salt (IDG-4Na) and iminoglutaricsuccinic acid tetra sodium salt (IGS- 4Na), were synthesized in reasonably good yield and purity. The commercially unavailable precursor for the two ligands, ethyl p-aminoglutarate, was synthesised in high yield and purity, and together with the two ligands were fully characterized by means of melting point measurements and various spectrometric techniques CH-NMR, 13C-NMR, MS and IR). For the first time, an electrochemical study has been conducted on the complexes of these ligands with selected transition metal ions (Zn2+, Cu2+ and Cd2+). An electrochemical technique, cyclic voltammetry (CV), was utilized on the study of the complexing ability of the ligands to the selected metal ions. An electrochemical cell comprising three electrodes was employed: thin film mercury coated carbon microelectrode was used as the working electrode, a Platinum wire as the auxiliary electrode, and a Ag/AgCI as the reference electrode. CV has been used and proven to offer a convenient route towards the determination of metal-ligand complex stability constants in aqueous media". The values of the logarithms of the metal-ligand formation constants obtained by this technique, when compared with other widely used aminopolycarboxylic acids (APCAs), show better complexing ability of the ligands with the transition metal ions. When the two ligands are compared, IGS showed greater affinity towards the selected transition metal ions. This is due to the fact that, in aqueous media, as the side chain ligators decrease, the stabilization energy of the complex increases. The formation stability constants were determined by plotting the change in the reduction potential (ΔE) against solution pH. A process making use of a modification of lingane equation was used. / AFRIKAANSE OPSOMMING: Twee nuwe potensieel bio-afbreekbare amienpolikarboksielsuurligande, iminobiglutaarsuur -tetranatriumsout (IBG-4Na) en iminoglutaarsuksiensuurtetranatriumsout (IGS-4Na), was vervaardig met redelike goeie opbrengs en suiwerheid. Die kommersïeel onverkrygbare voorloper van die twee ligande, etiel-B-aminoglutaraat, was berei met hoë obrengs en suiwerheid, en was saam met die twee ligande ten volle geïdentifiseer deur middel van smeltpunt bepalings en verskeie spektrometriese tegnieke CH-KMR, 13C-KMR, MS en IR.). Vir die eerste keer is 'n elektrochemiese studie uitgevoer op die komplekse van hierdie ligande met selektiewe oorgangsmetaalione (Zn2+, Cu2+, en Cd2+). 'n Elektrochemiese tegniek, sikliese voltametrie (SV), is gebruik om die komplekseringsvermoë van die ligande ten opsigte van die geselekteeerdr metaalione te bestudeer. 'n Elektrochemiese sel wat bestaan uit drie elektrodes is gebruik: 'n Dunlaag kwikelektrode bedek met koolstof is gebruik as die werkselektrode, 'n platinumdraad as die bykomende elektrode en 'n Ag/AgCI elektrode as die verwysingselektrode. SV is voorheen gebruik en bewys as 'n gerieflike metode vir die bepaling van metaalligandkompleksstabiliteitskonstantes in waterige media'. Die waardes van die logaritmes van die metaalligandvormingskonstantes wat verkry word deur hierdie tegniek, soos vergelyk met ander algemeen gebruikte amienpolikarboksielsure (APKSe), vertoon beter komplekseringsvermoë met die ligande deur middel van die oorgangsmetaalione. Wanneer die twee ligande met mekaar vergelyk word, het IGS-4Na groter affiniteit gehad vir die oorgangsmetaalione. Dit is as gevolg van die feit dat die stabiliteitsenergie van die kompleks in waterige media verminder word soos wat die sykettings van die ligande toeneem. Die vormingstabilitietskonstantes was bepaal deur 'n varandering in reduksie potensiaal (ΔE) teenoor die pH van die oplossings te plot. Die grafieke is verkry deur 'n aanpassing van die Lingnane-vergelyking te gebruik.

In this study, reversed phase HPLC with dual UV photodiode (PDA) and fluorescence (FL) detection were used to investigate copper complexes with fulvic, caffeic, vanillic, salicylic, and adipic acids. Application of the RE method provided valuable information on the retention behavior and spectral characteristics of FA and model compounds. Even though the method was only applicable to VA, the use of the PDA detector allowed the UV-V is scanning of the separated peaks. This allowed the comparison between the UV-Vis spectra of uncomplexed species. The overall results provide an experimental framework for validation of the proposed Cu-humate interaction models.

Call number: LD2668 .T4 1979 B57 / Master of Science

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)°].

Thesis (MSc)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: This study comprises the synthesis and full characterization of two novel pendant-arm donor macrocyclic ligands. The stability and structure of the complexes of these two ligands with a series of metals ions [Mn(II), Co(II), Zn(II), Cd(II), Pb(II)], was subsequently investigated. The two parent macrocyclic ligands, 1,4,7-triazacyclodecane ([10]-ane-N3) and 1,4,8- triazacycloundecane ([11]-ane-N3) were synthesized by means of the "direct synthesis" method using tosylates as protecting groups. Pendant arms were then added to the parent molecules to create hexadentate ligands. The two macrocyclic ligands are asymmetric because of the different lengths of the carbon bridges between the N-donor atoms of the rings. This feature gives the ligands the possibility to form both five- and six-membered rings when coordinated to metal centers. The ligands were fully characterized by means of NMR, mass spectrometry and elementalanalysis. Melting points were also determined. These two novel (triaza macrocyclic) ligands now complete the series between 9-ane- N3 [with its 2-(S)-hydroxypropyl pendant arms] and 12-ane-N3 [with its 2-(S)- hydroxypropyl pendant arms]. Protonation data of the ligands were determined using potentiometric titrations. The respective protonation constants for both ligands in 0.1000 mol dm-3 NaNO3 are: THTD log H 1 K = 9.176 and log H 2 K = 4.20 THTUD log H 1 K = 11.32 and log H 2 K = 5.87 A third protonation constant for both ligands (THTD and THTUD) was observed, but the use of potentiometric methods could not produce reliable values at very low pH values. stability constants of the new ligands with a series of metal ions were determined using 0.1000 mol dm-3 NaNO3 as ionic medium. The log(K) values at 25°C with THTD are: Co(II) 22.93 Zn(II) 14.82 Cd(II) 19.38 Pb(II) 15.47 The log(K) values at 25°C with THTUD are: Co(II) 17.52 Zn(II) 16.43 Cd(II) 18.05 Pb(II) 14.63 Very stable complexes were obtained with the larger Cd(II) ion when compared to other similar ligands. Crystal structures of some of the metal complexes were determined by X-ray crystallography. Metal perchlorates were used in the preparation of the metal complexes with THTD and THTUD, and various methods were utilized for the crystallization process. The general formula for these complexes is [M(L)]2+·2(ClO4)- where M=metal ion and L= neutral ligand. The bond lengths between the nitrogen atom and the metal ion, and the oxygen atom and the metal ion are very much the same in the respective crystal structures. This means that the metal ion lies almost halfway between the nitrogen and the oxygen atoms. The Mn(II)-THTD complex featured both a distorted octahedral and distorted trigonal prismatic configuration in the unit cell. Co(II)-THTUD contains three molecules per unit cell all having a distorted octahedral configuration. Zn(II)-THTUD crystallizes with six molecules per unit cell. / AFRIKAANSE OPSOMMING: Hierdie studie behels die bereiding en volledige karakterisering van twee oorspronklike hangkroonarmdonor makrosikliese ligande. Die stabiliteite en struktuur van komplekse van hierdie twee ligande met ’n reeks metaalione [Mn(II), Co(II), Zn(II), Cd(II), Pb(II)] is ondersoek. Die twee basis ligande 1,4,7-triazasiklodekaan (10-ane-N3) en 1,4,8-triazasikloundekaan (11- ane-N3) is gesintetiseer deur middel van die "direkte bereidingsmetode" met tosilate as beskermingsgroepe. Hangkroonsyarms is aangeheg om die vorming van ’n heksadentate ligand te bewerkstellig. Die twee makrosikliese ligande is asimmetries as gevolg van die verskillende lengtes van die koolstofbrûe tussen die N-donor atome van die ringe. Hierdie eienskap gee aan die ligande die vermoë om beide vyf- en seslidringe te vorm wanneer komplekse gevorm word met metaalione. Die ligande is ten volle gekarakteriseer deur middel van KMR-metings, massa-spektroskopie en element analise. Smeltpuntbepalings is ook uitgevoer. Die twee nuwe ligande voltooi nou die homoloë reeks tussen 9-ane-N3 [en sy 2-(S)- hidroksiepropiel hangkroonarms] en 12-ane-N3 [en sy 2-(S)-hidroksiepropiel hangkroonarms]. Protonasiedata van die ligande is bepaal deur middel van potensiometriese titrasie. Die onderskeie protonasiekonstantes vir beide ligande in 0.1000 mol dm-3 NaNO3 is: THTD log H 1 K = 9.176 en log H 2 K = 4.20 THTUD log H 1 K = 11.32 en log H 2 K = 5.87 ’n Duidelik-waarneembare derde protonasiekonstante vir beide ligande (THTD en THTUD) is opgemerk, maar potentiometriese metodes kon nie betroubare waardes lewer by die uiters lae pH-lesings nie. Vormingskonstantes van die ligande met ’n reeks oorgangsmetale is bepaal deur gebruik te maak van ’n 0.1000 mol dm-3 NaNO3 as ioniese medium. Die log(K) waardes by 25°C vir THTD is: Co(II) 22.93 Zn(II) 14.82 Cd(II) 19.38 Pb(II) 15.47 Die log(K) waardes by 25°C met THTUD is: Co(II) 17.52 Zn(II) 16.43 Cd(II) 18.05 Pb(II) 14.63 Uiters stabiele komplekse is verkry met die groter Cd(II) ioon in vergelyking met ander soortgelyke ligande. Kristalstrukture van sommige van die metaalkomplekse is bepaal deur middel van X-straal kristallografie. Metaalperchlorate is gebruik om metal komplekse met THTD en THTUD te berei, en ’n verskeidenheid kristallisasieprosesse is gebruik. Die algemene formule vir hierdie komplekse is [M(L)]2+·2(ClO4)- waar M = metaal ioon en L = neutrale ligand is. Die bindingslengtes tussen die stikstof atoom en die metaalioon, en die suurstof atoom en die metaalioon is nagenoeg dieselfde in die onderskeie kristalstukture. Dit beteken dat die metaalioon ongeveer halfpad tussen die stikstof en die suurstof atome voorkom. Die Mn(II)- THTD-kompleks vertoon beide oktahedrale - en trigonaal prismatiese konfigurasie in die eenheidsel. Co(II)-THTUD het drie molekule per eenheidsel, almal verwronge oktahedrale konformasies. Zn(II)-THTUD het gekristaliseer met ses molekule per eenheidsel.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / This study involved the preliminary investigation into the potential liquid-liquid extraction of Os(IV/III) from hydrochloric acid solutions with ligands of type N,N-dialkyl-N′-acyl(aroyl)thioureas (HL), and ultimate selective pre-concentration and separation of Os(IV/III) from the other platinum group metals. Investigations have also been focused towards understanding the speciation of Os(IV) in hydrochloric acid medium. A series of osmium complexes with ligands of type HL have been synthesised and characterised. This has been done with a view towards understanding the interaction of Os(IV/III) with the HL ligands, and what the resultant stereochemical influences would be on the solvent extraction capabilities of the ligands. The structures of two novel osmium-containing compounds have been verified by means of X-ray crytallography. Firstly, the ion pair OsCl6[(C4H9)4N]2 was obtained as a result of liquid-liquid extraction experiments. Secondly, the only known example (in our knowledge) of an Os(III) - N,N-dialkyl-N′- aroylthiourea complex, in this case tris(N,N-diethyl-N’-benzoylthioureato)osmium(III), was successfully synthesised and characterised. Lastly, preliminary studies into the substitution reactions of ruthenium-polypyridine complexes with N,N-dialkyl-N′-acyl(aroyl)thioureas were conducted. A series of cis-bis(2,2′-bipyridine)(N,N-dialkyl-N′-acyl(aroyl)thioureato)ruthenium(II) complexes have been successfully synthesised and characterised. The electronic absorption behaviour of the formed complexes have been investigated in detail via UV-Vis spectrophotometry.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The determination of the concentrations of the transition metals Mn2 +, Cu2 + and Fe3 + in various types of pulps was carried out using a combination of chelation with Ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (S,SEDDS) and capillary zone electrophoresis (CZE) coupled with diode array uvdetection. The metals were found to be inhomogeneously distributed in the pulps, and therefore a relatively large (20 gms) pulp samples were taken for analysis. Heating the pulp samples at 45°C with stirring for three hours was used to leach the metals into an aqueous phase for complexation with the ligands. Leaching with EDTA enabled the quantitative determination of 0.0091,0.0048 and 0.0014 mM Cu2 + and 0.0088, 0.0012 and 0.0016 mM Mn2 + in the three types of pulps analyzed respectively while detection of Fe3 + was not possible using EDTA. The use of [S,S-EDDS] as the leaching agent on the other hand enabled the quantitative determination of 0.0041, 0.0036 and 0.0031 mM Cu2+ and 0.0024, 0.0018 and 0.0047 mM Fe3+ in the three types of pulps analyzed respectively while determination of Mn2 + was not possible using [S,S-EDDS] as the leaching agent. [S,S-EDDS] was generally better in complexing iron and copper than EDTA. The leaching procedure employed and the detectors response to specific analytes formed were found to be the most important factors in the analysis of the metals in pulp. / AFRIKAANSE OPSOMMING: Die konsentrasies van die oorgangsmetale Mn2 +, Cu2 + and Fe3 + in verskeie tipes pulp is bepaal met behulp van 'n kombinasie van kelasie met etileendiamientetra-asynsuur (EDTA) en etileendiamiendisuksiensuur (S,S-EDDS) en kapillêre elektroforese (CE) gekoppel met UV-deteksie. Daar is bevind dat die metale oneweredig versprei is in die pulp monsters, en gevolglik is relatiewe groot (20 g) monsters gebruik vir die analiese. Die metale is ge-ekstraeer deur kompleksasie met die kelasie-agente in die water-fase, deur die pulp monsters vir drie uur te roer by 45°C. Ekstraksie met EDT A is gebruik om 0.0091,0.0048 en 0.0014 mM Cu2 + en 0.0088,0.0012 and 0.0016 mM Mn2 + in drie tipes pulp te bepaal, terwyl Fe3 + nie waargeneem is met behulp van EDTA nie. Deur [S,S-EDDS] te gebruik as ekstraksie-agent, is 0.0041, 0.0036 en 0.0031 mM Cu2+ en 0.0024, 0.0018 en 0.0047 mM Fe3+ in die drie tipes pulp waargeneem. Die analise van Mn2 + was nie moontlik met die metode nie. Daar is gevind dat die keuse van ekstraksie metode en die detektor-sensitiwiteit vir spesifieke metale die mees bepalende faktore in die analise van metale in pulp monsters is. EDDS was 'n beter keiaat vir Fe3 + en Cu2 + as EDTA.

Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Pt(JV) complexes with S, 0-donating aroylthioureas have been synthesized by oxidative addition of elemental halogens to the Pt(JJ) precursors, leading to the first-reported crystal structures of Pt(JV) with this class of ligand. The treatment of Pt(II) complexes of N,N-diethyi-N'-benzoylthiourea with 12, Br2 and Cl2 leads to facile oxidative addition of the halogens to the platinum center, yielding several geometric isomers, as determined by 195Pt NMR; the products cis-bis(N ,N-diethyi-N' -benzoylthioureato )diiodoplatinum(IV), 26, and cisbis( N,N-diethyl-N'-benzoylthioureato)dibromo-platinum(IV), 27, have been isolated and structurally characterized. Reaction of cis-/trans-bis(N-benzoyi-N'-propylthiourea-kS)dibromoplatinum(II) with Br2, similarly results in oxidative addition of the dihalogen, yielding the product trans-bis(N-benzoyi-N'propylthiourea- kS)tetrabromoplatinum(IV), 29. lz, however, does not undergo oxidative addition to cis! trans-bis(N-benzoyi-N' -propylthiourea-kS)diiodoplatinum(II), instead the iodine inclusion compound trans-bis(N-benzoyl-N'-propylthiourea-kS)diiodoplatinum(II) diiodine, 28, was isolated. Short intermolecular I··· I interactions in crystals of compounds 26 and 28 lead to infinite chains of weakly linked molecules in the respective solids. 195Pt NMR reveals that the 3: 3 Pt(II) metallamacrocycle of 3,3,3',3'-tetra(n-butyl)-l,l'terephthaloylbis( thiourea) undergoes stepwise oxidative addition of 12 or Br2 to each of the Pt(II) centers, upon treatment with the dihalogens. Treatment of the 2: 2 Pt(II) complex of 3,3,3',3'-tetraethyl-1,1'isophthaloylbis( thiourea) with 12 also results in the oxidative addition of the halogen, yielding a 2 : 2 trans-Pt(IV)-iodo metallamacrocycle, 35. The corresponding trans-Pt(IV)-X (X= Br, Cl) complexes were synthesized by oxidative addition in an electrolytic cell containing the 2 : 2 Pt(II) precursor and an appropriate halide salt in dichloromethane. The 2: 2 trans-Pt(IV)-X (X= I, Br, Cl) metallamacrocycles, 36 an 37, were isolated and structurally characterized. Intermolecular 1···1 interactions between molecules of 35, in crystals of the compound, result in chains of weakly connectedmolecules in the lattice. 195 Pt NMR is used as a sensitive probe for studying the hydration/solvation spheres of the PtX/ (X = Cl, Br) anions, and to investigate the occurrence of {Na + [PtCl/"]}" contact ion-pairing in non-aqueous solutions. The 195Pt NMR chemical shifts of the Pt~2 • (X = Cl, Br) anions in D20 and in various organic solvents have been determined, and are discussed with regard to solvent polarities and donor and acceptor properties. The non-linear variations of bp1•195 for the anions with changing bulk composition in aqueous binary mixtures with the organic solvents, suggest that the anions are preferentially solvated by the organic solvents relative to water. The anion solvation sphere compositions with changing bulk composition, as well as preferential solvation equilibrium constants, K11 ", are determined from the NMR data. Significant non-linear variations of the 195Pt NMR chemical shift for methanol and acetonitrile solutions of PtXt (X = Cl, Br) ·with increasing NaCI04 concentrations indicate the occurrence of {Na+[PtX6 2_]}_ contact ion-pair formation in these solutions. By contrast, the variation of Dp1•195 for aqueous solutions of the halogenoplatinate anions with increasing sodium perchlorate concentration is slight, revealing that Na+···PtXe?- ion association is not favoured in the aqueous medium. The 195Pt chemical shift variations are used to estimate conditional ion-pair formation equilibrium quotients, Q (M"\ for {Na+[Ptxi·Jr contact ion-pair formation in water, methanol and acetonitrile. The estimated Q values illustrate that the extent of {Na+[Ptxi·Jr ion-pairing increases in these solvents in the order water< methanol< acetonitrile, which is in accordance with the solvent donor and acceptor properties. / AFRIKAANSE OPSOMMING: Pt(JV) komplekse met S, 0-donerende aroi"eltioiireum ligande is deur middel van die oksidatiewe addisie van halogene aan Pt(JJ) uitgangskomplekse gesintetiseer; die kristalstrukture van die Pt(IV) komplekse met hierdie tipe ligande word vir die eerste keer gerapporteer. Die behandeling van die Pt(II) komplekse van N,N-dietiel-N'-bensoieltioiireum met 12, Br2 en Cl2 gee geredelik aanleiding tot die oksidatiewe addisie van die halogene aan die platinum sentrum, en lei, volgens bepaling met 195Pt KMR, tot die vorming van verskeie geometriese isomere; die produkte cis-bis(N,Ndietiel- N' -bensoieltioiireato )di-jodoplatinum(IV), 26, en cis-bis(N,N-dietiel-N' -bensoieltioiireato )dibromoplatinum( IV), 27, is geisoleer en kristallografies gekarakteriseer. Reaksie van cis-/trans-bis(N-bensoiel-N'propieltioiireum- IGS)dibromoplatinum(II) met Br2, lei ooreenkomstiglik tot oksidatiewe addisie van die halogeen, met trans-bis(N-bensoiel-N' -propieltioiireum-IGS)tetrabromoplatinum(IV) as produk, 29. 12 ondergaan egter nie oksidatiewe addisie aan cis-ltrans-bis(N-bensolel-N' -propieltioiireum-IGS)dijodoplatinum( II) nie; 'n verbinding waarin h ingesluit word in 'n kristalstruktuur met trans-bis(N-bensoielN'- propieltioiireum-IGS)di-jodoplatinum(II), word geisoleer, 28. Kort intermolekulere 1···1 interaksies in die kristalstrukture van verbindings 26 en 28 lei tot die ontstaan van swak-gebonde molekuul-kettings in die kristalle. 195Pt KMR dui aan dat met behandeling van die 3 : 3 Pt(II) metallomakrosikliese kompleks van die 3,3,3' ,3 '-tetra(n-butiel)-1, 1 '-tereftaloielbis(tioiireum) ligand met 12 of Br2, daar stapsgewyse oksidatiewe addisie van die halogene aan die Pt(II) ione in die kompleks plaasvind. Behandeling van die 2 : 2 Pt(II) kompleks van 3,3,3' ,3 '-tetraetiel-1, 1 '-isoftaloielbis(tioiireum) met 12 gee ook aanleiding tot oksidatiewe addisie, met 'n 2 : 2 trans-Pt(IV)-jodo metallomakrosikliese kompleks as produk, 35. Die ooreenkomstige trans-Pt(IV)-X (X = Br, Cl) komplekse is gesintetiseer deur middel van oksidatiewe addisie in 'n elektrolitiese se! wat die 2 : 2 Pt(II) uitgangskompleks bevat tesame met 'n toepaslike haliedsout in dichlorometaan. Die 2 : 2 trans-Pt(IV)-X (X = I, Br, Cl) komplekse, 36 en 37, is geisoleer en kristallografies gekarakteriseer. lntermolekulere I··· I interaksies tussen molekule in kristalle van verbinding 35, gee aanleiding tot kettings van swak-gebonde molekule in die struktuur. 195 Pt KMR word gebruik om die hidraterings-/solvaterings-sfere van die PtX/" (X = Cl, Br) anione te ondersoek, asook om die voorkoms van {Na + [PtCIX/}F kontak-ioonparing in nie-waterige oplosmiddels te bestudeer. Die195Pt KMR chemise verskuiwing van die PtXl" (X= Cl, Br) anione in D20 en in verskeie organiese oplosmiddels is bepaal, en word bespreek met verwysing na die polariteite asook die donor- en akseptoreienskappe van die oplosmiddels. Die nie-lineere variasies van Op1_195 vir die anione met veranderende oplosmiddelsamestelling in waterige binere mengsels met die organiese oplosmiddels, dui aan dat die anione by voorkeur deur die organiese oplosmiddels gesolvateer word. Die solvateringssamestelling van die anione met veranderende oplosmiddelsamestelling, asook ewewigskonstantes vir die voorkeur-solvatering deur die organiese oplosmiddels, K11 ", word met behulp van die KMR data bepaal. Beduidende nie-lineere variasies van Op1_195 in metanol en asetonitriel oplossings van PtXl" (X = Cl, Br) met toenemende NaC104 konsentrasies, dui op die voorkoms van {Na +[PtClxl-]}- kontak-ioonparing in die oplossings. Die variasies van Op1_195 in waterige oplosings van die anione met toenemende NaC104 konsentrasies is egter minder beduidend, waaruit afgelei kan word dat ioonparing nie in die waterige medium bevoordeel word nie. Die 195Pt chemiese verskuiwings word gebruik om kondisionele ioonpaarvormings-ewewigskwosiente, Q (M-1 ), vir die vorming van {Na+[PtCIXtJr in water, metanol en asetonitriel af te lei. Die Q-waardes dui in ooreenstemming met die donor- en akseptoreienskappe van die onderskeie oplosmiddels aan dat die voorkoms van kontak-ioonparing toeneem vir die oplosmiddels in die volgorde water < metanol < asetonitriel.