Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Modification of chitosan with benzoylisothiocyanate was attempted, however due to
solvent problem the study was left incomplete till appropriate solvent is designed.
N,N-diethyl-N -camphanoylthiourea (HL8), N-piperidyl-N '-camphanoylthiourea (HL9),
N-pyrrolidyl-N -camphanoylthiourea (HL10) and N,N-diethyl-N -adamantylcarbonyl
thiourea (HL11)have been synthesised and characterised for the first time. Two of
these ligands HL8 and HL11, were used to form a number of transition metal
complexes, namely H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2],
translcis-[Zn(L 8_S,0)2], translcis-[Pt(L 8_S,0)2], Ag2[(HL8-S)(L-J.1-S,O)]2, translcis-
[Ni(L11-S,O)2]and translcis-[Cu(L11_S,O)2]. The new products are fully characterised
by means of MS, IR spectroscopy, NMR spectroscopy, elemental (C, H, Nand S)
analysis and melting point determinations. The H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8-
S,O)2], trans-[Cu(L8-S,O)2] and Ag2[(HL8-S)(L-J.1-S,O)]2 are also characterised by Xray
diffraction analysis.
The structure of the new chiral N,N-dialkyl-N' -camphanoylthiourea ligand (HL8) has a
significant effect on its coordination chemistry with transition metal ions. This ligand
forms H30+ {fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L-S,O)2] and Ag2[(HL8-
S)(L8-J.1-S,O)]2 complexes with the Co(II), Ni(II), Cu(II) and Ag(I) metal ions
respectively. The spectroscopic and X-ray diffraction results of these complexes
indicate a bidentate mode of coordination of the ligand (with its Sand °donor
atoms) to the Co(II), Ni(II) and Cu(II) metal ions. The reaction of this ligand with
silver(I) however affords the formation of a binuclear silver(I) complex exhibiting
monodentate and bidentate modes of coordination within the same complex. The
exclusive formation of trans-[Cu(L8-S,0)2] is a new phenomenon for the HL type
thiourea ligands with Sand °donor atoms. Up to this point a maximum of 15 %
trans-isomer has been reported in ltterature."
All the transition metal complexes made with HL8and HL11are air stable in both the
liquid and solid states except the H30+{fae-[Co(L 8-S,Ob]} Interestingly the deep
green fae- H30+{fae-[Co(L8-S,Obn complex is air sensitive and the Co(II) oxidizes to
Co(III) in the complex by atmospheric O2. The oxidation of Co(II) to Co(III) in the
complex is confirmed by 1Hand 13CNMR spectra as well as by UV-Visible spectra of the complex. The NMR spectra of the complexes indicated the presence of one
isomer in each complex except for the NMR spectra of the platinum complex of the
HL8 ligand. The presence of the minor trans-[Pt(L8-S,Q)21 isomer in combination with
the major cis-[Pt(L8-S,Q)21 isomer in the platinum complex was indicated by the 1H,
13Cand 195ptNMR spectra of the complex. / AFRIKAANSE OPSOMMING: Pogings om chitosan met benzoylisothiocyanate te modifiseer is onvoltooid gelaat
weens die gebrek aan'n geskikte oplosmiddel.
N,N-diethyl-N -carnphanoylthiourea (HL8), N-piperidyl-N -camphanoylthiourea (HL9),
N-pyrrolidyl-N -camphanoylthlourea (HL10) en N,N-diethyl-N -adamantylcarbonyl
thiourea (HL11) is vir die eerste keer gesintetiseer en gekarakteriseer. Twee van die
ligande, HL8 en HL11, is gebruik om verskeie oorgangsmetaalkomplekse te berei, nl.
H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2], trans/cis-[Zn(L8
-
S,0)2], trans/cis-[Pt(L8-S,0)2], Ag2[(HLB-S)(L-jl-S,0)]2, trans/cis-[Ni(L11-S,0)2] en
trans/cis-[Cu(L11_S,0)2]. Die nuwe produkte is volledig gekarakteriseer deur middel
van MS, IR spektroskopie, KMR spektrometrie, elemente (C, H, N en S) analise en
smeltpuntbepaling. Die komplekse H30+{fao-[Co(L8-S,0)3n, cis-[Ni(L8-S,0)2], trans-
[Cu(L8-S,0)2] en Ag2[(HLB-S)(L-jl-S,0)]2 is ook deur middel van X-straaldiffraksieanalise
gekarakteriseer.
Die struktuur van die nuwe chirale N,N-dialkyl-N'-camphanoylthiourea ligand (HL8)
het In beduidende invloed op die koordinasie van hierdie ligand met
oorgangsmetaalione. Die ligand vorm H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2],
trans-[Cu(L-S,0)2] en Ag2[(HL8-S)(L8-Il-S,0)]2 komplekse met Co(ll)-, Ni(II)-, Cu(II)-
en Ag(I)-ione respektiewelik. Spektroskopiese en X-straaldiffraksie-analise van die
komplekse toon dat die ligande op 'n bidentate wyse d.m.v. die S- en O-donoratome
met Co(II), Ni(lI) en Cu(lI) koordineer. Die reaksie van hierdie ligand met Ag(I)-ione
lei egter tot die vorming van 'n dikernige silwer(I)-kompleks waarin die ligande
monodentaat (S) en bidentaat (S en 0) aan die metaal gebind is. Die vorming van
uitsluitlik die trans-[Cu(L8-S,0)2] in die reaksie van HL8 met Cu(lI) is 'n besondere
fenomeen in die chemie van hierdie tipe ligande; in die literatuur word melding
gemaak van slegs een ander trans-kompleks met hierdie ligande, en dan wel met 'n
maksimum opbrengs van 15%.29
Alle oorgangsmetaalkomplekse met HLB en HL11 is stabiel indien blootgestel aan lug,
ongeag of die verbindings opgelos word of in die vastetoestand verkeer, behalwe
H30+{fao-[Co(L8-S,Ohn. Die diep-groen gekleurde H30+{fao-[Co(L8-S,Ohn)3]} kompleks is lugsensitief; Co(lI) word deur lugsuurstof na Co(lIl) ge-oksideer. Die
oksidasie in die kompleks kan deur middel van 1H en 13CKMR spektrometrie sowel
as UV-sigbare spektrofotometrie bevestig word. Die KMR spektra van alle komplekse
dui op die teenwoordigheid van slegs een isomeer in oplossing, behalwe in die geval
van die platinum(lI) kompleks met HL8. Die teenwoordigheid van lae konsentrasies
trans-[Pt(L8-S,0)2] isomeer tesame met veel hoër konsentrasies van die cis-[Pt(L8
-S,O)2] isomeer word deur 1H, 13Cen 195ptKMR spektroskopie aangedui.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53610 |
| Date | 12 1900 |
| Creators | Ghebregziabiher Berhe, Haile |
| Contributors | Koch, K. R., Bredenkamp, M. W., 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 | English |
| Type | Thesis |
| Format | 135 p. : ill. |
| Rights | Stellenbosch University |
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