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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50362 |
| Date | 12 1900 |
| Creators | Westra, Arjan Nicolaas |
| Contributors | Koch, Klaus R., Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 195 p : ill. |
| Rights | Stellenbosch University |
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