This Thesis describes some theoretical studies on ligated and bare clusters. Chapter 1 gives a review of the two theoretical models, Tensor Surface Harmonic Theory (TSH) and Jellium Model, accounting for the electronic structures of ligated and bare clusters. The Polyhedral Skeletal Electron Pair Theory (PSEPT), which correlates the structures and electron counts (total number of valence electrons) of main group and transition metal ligated clusters, is briefly described. A structural jellium model is developed in Chapter 2 which accounts for the electronic structures of clusters using a crystal-field perturbation. The zero-order potential we derive is of central-field form, depends on the geometry of the cluster, and has a well-defined relationship to the full nuclear-electron potential. Qualitative arguments suggest that this potential produces different energy level orderings for clusters with a nucleus with large positive charge at the centre of the cluster, enabling the spherical jellium model to be applied to alkali metal clusters seeded with magnesium and zinc. Analysis of the effects of the non-spherical perturbation on the spherical jellium shell structures leads to the conclusion that for a cluster with a closed shell electronic structure a high symmetry arrangement which is approximately or precisely close packed will be preferred. It also provides a basis for rationalising those structures, which have been predicted using ab initio calculations, of clusters with incomplete shell electronic configurations In Chapter 3, the geometric conclusions derived in the structural jellium model are developed in more detail. Alkali metal clusters with closed shell electronic configurations according to the jellium model adopt geometries of high symmetry and based on the T_d , O_h and I_h point groups. For high nuclearity clusters alternative high symmetry structures can occur and those which are either the most close packed or spherical are predicted to be the most stable. When the jellium closed shell "magic numbers" coincides with one of these high symmetry structures then the cluster will be particularly stable. The group theoretical consequences of the Tensor Surface Harmonic Theory are developed in Chapter 4 for[ML₂]_n, [ML₄]_n and [ML₅]_n clusters where either the xz and yz or x²-y² and xy components to L^π_d and L^δ_d do not contribute equally to the bonding. The closed shell requirements for such clusters are defined and the orbital symmetry constraints pertaining to the interconversion of conformers of these clusters are described. In Chapter 5 Stone's Tensor Surface Harmonic methodology is applied to high nuclearity transition metal carbonyl cluster compounds with 13-44 metal atoms. Two limiting bonding situations are identified and represented in terms of general electron counting rules. If the radial bonding effects predominate the clusters are characterised by 12n_s+Δ_i valence electrons, where Δ_i is the characteristic electron count of the interstitial moiety. If radial and tangential bonding effects are important then the total number of valence electrons is 12n_s+2(s_s+s_i-l), where s_s and s_i are the number of skeletal bonding molecular orbitals associated with surface (s_s) and interstitial (s_i) moieties. Chapter 6 develops a new theoretical framework to account for the bonding in the high nuclearity ligated clusters with columnar topologies. The wave functions of columnar metal clusters can be expressed as an expansion based on the particle on the cylinder problem. This bonding analysis is applied to clusters containing columns of triangles and squares. In Chapter 7 the origin of non-bonding orbitals in molecular compounds is reviewed and analysed using general quantum mechanical considerations. A combination of the pairing theorem and a group theoretical analysis leads to a definition of the number of the non-bonding molecular orbitals in co-ordination, polyene and cluster compounds. The non-bonding molecular orbitals have been generated by defining the nodal characteristics of the relevant orbitals and evaluating the solutions under the appropriate boundary conditions. The stereochemical role of nonbonding molecular orbitals in co-ordination compounds is also discussed.

No description available.

Transition metal oxide thin films are commonly used in organic electronics devices to improve charge-injection between electrodes and organic semiconductors. Some oxides are good hole-injectors, while others are good electron-injectors. Transition metal oxides are materials with many diverse properties. Many transition metals have more than one stable oxidation state and can form more than one oxide. Each oxide possesses its own unique properties. For example, transition metal oxide electronic band structures can range from insulating to conducting. They can exhibit a wide range of work functions. Some oxides are inert, while others are catalytically active. Such properties are affected by numerous factors, including cation oxidation state and multiple types of defects. Currently it is not fully understood which oxide properties are the most important to their performance in organic electronics. In the present thesis, photoemission spectroscopy is used to examine how changes in certain oxide properties–such as cation oxidation states and defects—are linked to the oxide properties that are relevant to organic electronics devices—such as an oxide’s work function and electron band structure. In order to unravel correlations between these properties, we controllably change one property and measure how it changes affects another property. By performing such tests on a wide range of diverse transition metal oxides, we can discern broadly-applicable relationships. We establish a relationship between cation oxidation state, work functions and valence band structures. We determine that an oxide’s electron chemical potential relative to an organic’s donor and acceptor levels governs energy-level alignment at oxide organic interfaces. We establish how interfacial reactivity at electrode/oxide interfaces dictates an oxide’s work function and electronic structure near the interface. iii These findings demonstrate some of the very interesting fundamental relationships that exist between chemical and electronic properties at interfaces. These findings should assist in the future development and understanding of the functional interfaces of organic semiconductors and transition-metal oxides.

Chapter 1 reviews the relevant and particularly interesting chemistry of C₆₀ and includes some chemical aspects of the other recently discovered new forms of carbon including the graphitic carbon nanotubules, concentric carbon spheres and amorphous carbon networks. An experimental section describes the techniques used for the synthesis of fullerene rich soot and the subsequent isolation and purification of C₆₀ as performed in the Inorganic Chemistry Laboratory, Oxford. Chapter 2 describes the synthesis, characterisation, and some reaction chemistry of the new complex Rh(η²-C₆₀)(CO)(H)(PPh₃)₂ and its activity with respect to the catalytic hydroformylation of ethene and propene, and is compared to the industrially used catalyst Rh(CO)(H)(PPh₃)₃. Studies to determine the thermal stability of Rh(η²-C₆₀)(CO)(H)(PPh₃)₂ compared to Rh(CO)(H)(PPh₃)₃ during hydroformylation catalysis are also included. Chapter 3 describes the synthesis and characterisation of the new complexes NaC₆₀.5thf, NMe₄C₆₀.1.5thf and what could be the new complex Na_0.9C₆₀.3thf. These materials exhibit a magnetic transition at approximately 180K as determined by bulk static D.C. susceptibility measurements and electron spin resonance spectroscopy. This transition is discussed mainly in terms of a metal-metal or metal-insulator transition. Some reaction chemistry of these materials is also described. Also described are studies into various aspects of the sodium C₆₀ phase diagram at ambient temperature and pressure with regard to the proposed solid solution behaviour in the compositional range Na₁C₆₀ to Na₃C₆₀. The synthesis of the novel hexagonal close packed compounds Na₆C₆₀ and Na₉C₆₀ and consequences for the phase diagram of sodium C₆₀ intercalates are discussed. Chapter 4 describes the synthesis of various alkali metal C₆₀ intercalates using a microwave induced argon plasma as the heat source. The developement of this technique for the bulk synthesis of other materials and attempts at the synthesis of novel lithium and ytterbium intercalates are also described.

This Thesis describes some theoretical studies on cluster compounds of the main group and transition metal elements. Chapter 1 presents a review of the theoretical aspects of cluster chemistry. Three major theoretical approaches are identified, namely the localised, delocalised and free electron models and their historical development is described. The research described in this Thesis is based on extensions of Stone's Tensor Surface Harmonic (TSH) methodology, supported by Extended Huckel molecular orbital calculations. In Chapter 2, the TSH approach is used to describe the skeletal bonding in 3- and 4-connected polyhedral clusters. Like the deltahedral clusters, 4-connected molecules are generally characterised by (n+1) Skeletal Electron Pairs (SEP's). 3- connected clusters, however, possess 3n/2 SEP's. This difference is attributed to the occurrence of additional non-bonding orbitals in the 3-connected case. In Chapter 3, the bonding in a novel class of deltahedral metallaborane clusters is discussed. These hyper-closo or iso-closo species are studied from a fragment orbital viewpoint, regarding the structures as metal-capped fragments of a borane icosahedron. In this way, the problem of whether these clusters possess n or (n+1) SEP's is studied for n=9, 10 and 11. Although most deltahedral clusters conform to the (n+1) SEP rule, there are a significant number which do not. In Chapter 4, these deviations are rationalised from a group theoretical/topological viewpoint. A group theoretical paradigm is developed which simplifies the derivation of the frontier orbitals for these molecules. Chapter 5 extends the TSH methodology to clusters with bispherical topologies. To discuss these clusters, the TSH wavefunctions are modified to include radial, as well as angular nodes. The methodology is also applied to clusters with toroidal topologies, where the capping atoms form a ring around the equator of the inner cluster sphere. The bonding in π-donor- and π-acceptor-bridged clusters of the transition metals are compared in Chapter 6. Although the symmetry aspects are identical and lead to similar bonding patterns, the ir-donor clusters are characterised by a number of unoccupied d^δ-based orbitals. The bonding in a series of closo, nido and arachno π-donor clusters, based on edge- and face-bridged octahedral molecules is considered and a relationship between the cluster electron count and the number of unavailable d^δ-based orbitals is identified.

The oxidation of olefins by transition metal complexes leading to epoxide or ketonic products has been reviewed, with an emphasis on non-free radical processes. The formation of cycloadducts by reaction of <u>bis</u> (triphenylphosphine )- platinum(O)dioxygen with the α,β-unsaturated carbonyl compounds <u>trans</u> but-2-enal, propenal, cyclohex-2-en-1-one, <u>exo</u> 2-methvlenecyclohexan-1-one and 3-phenylprop- 2-enal was investigated by H- and ³¹P- nuclear magnetic resonance (n.m.r.). The cycloadducts derived from <u>trans</u> but-2-enal and propenal were thermally unstable in solution and further reacted to form stable, isolable complexes. The mechanism by which the cycloadduct <u>cis</u> [4-<u>trans</u>(prop-2-enyl )-1,1-bis( triphenyl - phosphine)platina-2,3» 5-trioxacyclopentane] , I , was transformed into <u>cis</u> [<u>trans</u>- (5-formyl-4-methyl)-1,1-bis(triphenylphosphine )platina-2 t 3-dioxacyclopentane] , II , was investigated by H- and H-n.m.r. utilising <u>trans</u> 4-[²H₃]but-2-enal. A mechanism which involved both exchange of free <u>trans</u> but-2-enal with I and reaction to give II was proposed; a computer model, based upon numerical integration of the alternative rate equations was in good agreement with this proposition. The chemical reactivity of II with a variety of reagents was explored. In particular, the reaction of II with trifluoroacetic acid gave <u>trans</u> 2-formyl- 3-methyloxirane in high yield and stereoselectivity. The dynamic behaviour of <u>cis</u>[<i>bis</u>(triphenylphosphine)(2₃,3'-m)(<u>trans</u> - but-2-enal )platinum(0)] was observed by variable temperature P-n.m.r. and explained by the interconversion of carbonyl rotamers. The preparation of iridium(I) olefin and peroxo complexes has been described Chloro<u>bis</u> triphenylphosphine) (1,2-m) (ethene )dioxygen iridium( I) , III , and related complexes were found to oxidise terminal olefins to their methyl ketones stoichiometrically, by a non-free radical process. The mechanism has been discussed.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 87-92). / viii, 92 leaves, bound ill. 29 cm

Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / With the increasing use of lasers it is necessary to develop materials that can provide protection to eyes and other sensitive devices. This thesis reports on an investigation into optical limiting of Transition Metal Acetylides (TMAs) that transmit ambient light levels of light but block high energy (laser) light across the visible part of the spectrum. A standard optical limiting testbed is used to measure opt~callimiting at 470, 532 and 630 om for a wide range of Pt:ethynyl related TMAs. I report the effect on optical limiting of altering the central bridge, heavy metal, terminal group, solubilising group and oligomerisation. Most of these materials showed poor optical limiting, especially in the red. Two dimers of Pt:ethynyl, however, have clamping levels at 532 om better than that for Pt:ethynyl. I therefore describe a detailed spectroscopic investigation of two series of oligomers and discuss their structure/property relationships. This investigation also includes a precursor ofPtethynyl, PEPE, which shows remarkable limiting. I also report modelling of optical limiting using a 5-level model constructed using the spectroscopic data. I show that the 5-level model can be validated and accurately predicts the limiting for PEPE against both ps and ns pulses. It can also be used to predict ps limiting for Pt:ethynyl and its oligomers. For ns pulses, however, it predicts much less limiting than that observed. I therefore propose a new mechanism that is important for ns limiting by TMAs. Finally I discuss the broadband limiting of these materials and from analysis of the measurements· I describe structures of materials that may show promising broadband optical limiting. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320307 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2008

Typescript (Photocopy) / Includes bibliographical references / xix, 290 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Physical and Inorganic Chemistry, University of Adelaide, 1989

2 v. : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Physical and Inorganic Chemistry, University of Adelaide, 1974