Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: A thorough search through the literature as well as through the Cambridge Crystallographic
Structural Database resulted in no examples of a neutral ozone acting as ligand in a complex
with any metal. Ionic compounds containing ozonide as anionic species, however, are well
known throughout the literature and not surprisingly the only result for 0₃ and a metal in the
CCSD was an ionic rubidium ozonide compound.
What follows is a systematic study into the result of placing an ozone ligand within
complexing distance of a transition metal (the first transition row from titanium to copper). Due
to the novelty of the system, as first approximation four different orientations of the ozone ligand
relative to the metal (a metal cation in these calculations) were investigated. It was found that
coordination through the terminal oxygens resulted in energy minima for all the metal cations,
although not necessarily the absolute energy minimum on the potential energy surface for the
specific cation. A further structural study was done by adding carbonyl and hydrogen ligands to
the system, according to the 18-electron rule. For these calculations coordination through the
terminal oxygens was employed. In both series the dissociation energy was also calculated. The
dissociation energies for the M(CO)nHm(0₃) complexes were all positive, indicating that they are
theoretically stable structures.
The resulting wave functions were then analysed with the help of three techniques: Atoms
in Molecules (AIM), Charge Decomposition Analysis (CDA) and Natural Bond Orbital Analysis
(NBO). AIM showed that bonds were indeed formed between the ozone ligand and the transition
metal and hinted that the bonding model can be interpreted with the Dewar-Chatt-Duncanson
(DCD) model of σ-donation and л-back donation. CDA confirmed that this was the case. NBO
results proved erroneous due to the largely delocalized electronic structure of the complexes. / AFRIKAANSE OPSOMMING: 'n Deeglike soektog deur die literatuur en die Cambridge Crystallographic Structural Database
het geen resultate gelewer van komplekse waarin 'n neutrale osoonligand komplekseer met 'n
metaal nie. Ioniese verbindings waarin die osonied as anioon optree, is wel bekend deur die
literatuur en die enigste resultaat in die CCSD - vir 'n soektog bevattende osoon en 'n metaal -
het 'n rubidiumosonied-verbinding opgelewer.
Wat volg is 'n stelselmatige studie om die effek te ondersoek indien 'n osoonligand naby
genoeg aan 'n oorgangsmetaal geplaas word om kompleksering te bevoordeel (metale wat
gebruik is, is die eerste oorgangsreeks vanaf titanium tot koper). As gevolg van die onbekendheid
van die sisteem is vier verskillende oriëntasies van die osoonligand relatied tot die metal ('n
metal katioon in die geval) as beginpunt ondersoek. Daar is gevind dat koordinasie deur die
terminale suurstowwe van die osoonligand vir al die metal katione lei tot energie minima,
alhoewel dié minima nie noodwendig die globale minima op die potensiële energie oppervlaktes
van die katione is nie. 'n Verdere studie is gedoen deur karboniel- en waterstofligande tot die
sisteem te voeg, gelei deur die 18-elektron reel. Vir hierdie berekeninge is koördinasie deur die
terminale suurstowwe gebruik. In beide reeks is dissosiasie-energieë bereken. Die dissosiasie energieë
van die M(CO)nHm(0₃) komplekse was deurgaan positief wat aandui dat die komplekse
teoreties stabiel is.
Die verkrygde golffunksies is hierna analiseer deur middel van drie tegnieke: Atoms in
Molecules (AIM), Charge Decomposition Analysis (CDA) en Natural Bond Orbital Analysis
(NBO). AIM het getoon dat bindings inderdaad gevorm word tussen die osoonligand en die metal
en bet die moontlikheid laat ontstaan dat die bindingsmodel volgens die Dewar-Chatt-Duncason
(DCD) model van σ-donasie en л-terugdonasie geïnterpreteer kan word. Hierdie waarneming is
bevestig deur CDA. NBO resultate kon nie suksesvol gebruik word nie as gevolg van die hoë
graad van electron delokalisasie van die komplekse.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52650 |
| Date | 12 1900 |
| Creators | Venter, Gerhard (Gerhard Abraham) |
| Contributors | Dillen, J. L. M., 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 | 109 p. : ill. |
| Rights | Stellenbosch University |
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