Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This study comprises the preparation and characterization of various novel
organometallic complexes of palladium(ll) which contain symmetric and
unsymmetric (heteroatom-containing) r..-dicarbonyl-type ligands, T]3-heteroallyl
ligands and T]3-coordinated trimethylsilyl-containing ligands.
With the ultimate objective of preparing potential catalytic precursors similar to
known catalytic precursors which exhibit hemilabile activity, the main goals of
this study were the following: -
• Investigate the coordination mode of the aforementioned ligand-types to
the palladium of the starting compound, trans-[Pd(CeHs)CI{P(CeHshhl (1),
by physical measurements.
• Carry out single crystal structure determinations where possible.
• Investigate the influence of the properties of the ligands on the stability of
the prepared complexes.
• Investigate the existence of hemilability (if any) in the prepared complex.
The deprotonated symmetric and unsymmetric f!,-dicarbonyl-type ligands
readily bind to the palladium of the starting compound in a bidentate fashion
through the oxygens by displacing a triphenylphosphine group and producing
easily removable sodium chloride. These complexes show that a negative
charge can be accommodated in a delocalized fashion by the -S=O and -
P=O groups of these acac--type ligands in a similar manner to the carbonyl
groups of acetylacetonate. However, no evidence of hemilabile activity was
found in this series of complexes.
In a similar fashion, the deprotonated T]3-heteroallyl ligands, L = [PhzPS£],
[PhCOz-], [PhC{NSi(CH3hhl [(Ph)zP{NSi(CH3hh-], were linked to palladium
in the same starting complex, in T]3-fashion by triphenylphosphine substitution.
No evidence of hemilabilty was evident in this series of complexes, but when
L = [PhzPSz-], an exchange of the coordinated triphenylphosphine group with
the free triphenylphosphine group was observed in the reaction mixture. Finally, the preparation, isolation and spectroscopic characterization of
several T\3-allyl paliadium(lI) complexes with ligands of the type
R-TeCH2CH2CQQCH3, (R = isopropyl, t-butyl ,ethyl) were attempted with the
compound bis-( T\3-allyl )-di-~ -iodo-dipalladium( II), [T\3 -( CH2CHCH2J2Pd212J,
which had also now been crystallographically characterized. Chelate
formation by TeAQ coordination seemed possible by halide precipitation with
silver tetrafluoroborate. Unfortunately the resulting compounds were too
unstable to be isolated in the pure form for characterization. / AFRIKAANSE OPSOMMING: Die studie behels die bereiding en karakterisering van verskeie nuwe
palladium(lI) organometaalkomplekse met inbegrip van simmetriese en
onsimmetriese (heteroatoom bevattende) ~-dikarboniel-tipe ligande, 113-
heteroallielligande en 113_gekoordineerdetrimetielsiliel bevattende ligande.
Met die beoogde einddoel die bereiding van potensiele katalitiese
voorgangers soortgelyk aan bekende katalitiese voorgangers met hemilabiele
aktiviteit, sluit die hoof mikpunte van die studie die volgende in: -
• 'n Ondersoek na koordinasie-wyse van die bogenoemde ligand tipes aan
die palladium van die uitgangstof, trans-[Pd(C6Hs)CI{P(C6Hshhl (1), met
behulp van fisiese bepalings.
• Enkel kristal struktuur bepalings waar moontlike.
• 'n Ondersoek na die invloed van die einskappe van die ligande op die
stabilitiet van die komplekse.
• 'n Ondersoek na die bestaan van hemilabiele aktiwiteit (indien enige) in die
voorbereide complekse.
Die gedeprotoneerde simmetriese en onsimmetriese ~-dikarboniel-tipe
ligande het geredelik, bidentaat deur middel van die suurstowwe gebind aan
die palladium van die uitgangstof deur die verplasing van die trifenielfosfien
group en die vorming van verweiderbare natriumchloried. Hierdie komplekse
dui aan dat 'n negatiewe lading wei geakkommodeer kan word deur
delokalisasie by die -S=O- en -P=O-groepe van hierdie acac"-tipe Iigande,
soortgelyk aan die karbonielgroep van asetielasetonaat. Geen hemilabiliteit is
waargeneem in hierdie reeks komplekse nie.
Die gedeprotoneerde 113-heteroalliel Iigande, L = [Ph2PS£), [PhCO£),
[PhC{NSi(CH3h}£), [(PhhP{NSi(CH3hhl is op 'n soortgelyke wyse 113-
gekoppel aan palladium van dieselfde uitgangstof met trifenielfosfien
verplasing. Geen hemilabiliteit is waargeneem in hierdie reeks komplekse nie, maar wanneer L = [Ph2PS£], is 'n uitruiling van 'n gekoordineerde
trifenielfosfien met 'n vrye trifenielfosfien in die reaksiemengsel waargeneem.
Die bereiding, isolasie en spektroskopiese karakterisering van Tj3-alliel
paliadium(lI) komplekse met ligande van die tipe R-TeCH2CH2COOCH3, (R =
isopropiel, t-butiel ,etiel) is gepoog met die uitgangstof bis-(Tj3-alliel)-di-ll-iododipaliadium(
II), [Tj3-(CH2CHCH2hPd2b], wat volledig gekarakteriseer was.
Chelaat-vorming deur TeAO-koordinasie het moonlik blyk te wees deur halied
presipitasie met behulp van AgBF4. Die komplekse is baie onstabiel en is dit
gevolglik nie moontlik am die komplekse suiwer te isoleer en te karakteriseer
nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21796 |
| Date | 12 1900 |
| Creators | Blewett, Gavin |
| Contributors | Raubenheimer, H.G., Brull, R., 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 | Unknown |
| Type | Thesis |
| Format | viii, 190 leaves : ill. |
| Rights | Stellenbosch University |
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