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Chapter 1 surveys the chemistry and reactivity of Group 14 and relevant Group 15 complexes and introduces the analogies which exist between the well-established ligand behaviour of non-metallic systems and the configuration of donor functionality present in a range of main group metallo-organic compounds. Chapter 2 initially looks at the reactivity of the anion [Sn {μ-N=C(<SUP>t</SUP>Bu)Ph}<SUB>3</SUB>]<SUP>-</SUP>, towards a variety of metals with the aim of using this complex as a tripodal ligand. However, the reaction of [Sn{μ-N=C(<SUP>t</SUP>Bu)Ph}<SUB>3</SUB>Li.THF] with [CuCl] results in ligand transfer of one of the imido groups, to form [Cu{μ-N=C(<SUP>t</SUP>Bu)Ph}]<SUB>4</SUB>.THF] and the presence of PPh<SUB>3</SUB> fails to block this transfer, thus [Cu{μ-N=C(<SUP>t</SUP>Bu)Ph}]<SUB>4</SUB>.2PPh<SUB>3</SUB>-THF is produced. The reaction of [Cp<SUB>2</SUB>Sn] with [2-LiPy] (2-Py = Pyridyl), formed from [<SUP>n</SUP>BuLi] with [2-PyBr], yields the Sn(IV) product [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiBr.0.5THF]. Investigations of this compound demonstrate the efficacy of the [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>] moiety as a robust neutral ligand. The reaction of [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiBr.0.5THF] with CuCl<SUB>2</SUB> yields the Cu(I) product [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>CuBr.0.5THF]. However, an attempt to extend this reactivity to AgNO<SUB>3</SUB> results in anion exchange, producing [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiNO<SUB>3</SUB>]. The Pb(II) complex [Pb(2-Py)<SUB>3</SUB>Li.THF] was synthesised from the reaction of [2-LiPy] with [Cp<SUB>2</SUB>Pb]. In Chapter 3, two alternative reaction pathways are identified in the nucleophilic substitution reactions of Group 14 metallocenes with lithiated primary amines [RNHLi]. These are exemplified by the synthesis of the primary tris(amido)stannate [(MANH)Sn(μ-NHMA)<SUB>2</SUB>Li.2THF] obtained from the reaction of [Cp<SUB>2</SUB>Sn] with [(MA)NHLi] (MA = 2-MeOC<SUB>6</SUB>H<SUB>4</SUB>), and the cubanes [ENCy<SUB>4</SUB>] [E = Sn, Pb ; Cy = C<SUB>6</SUB>H<SUB>11</SUB>] are prepared from [CyNHLi] and [Cp<SUB>2</SUB>E]. The later furnishes a new route to Group 14 imido cubanes. A study of the effects of two potent nucleophiles in the same molecule, [PhCH<SUB>2</SUB>N(Li)CH<SUB>2</SUB>)]<SUB>2</SUB>, with [Cp<SUB>2</SUB>Sn] was undertaken, yielding the dimer [{PhCH<SUB>2</SUB>N(CH<SUB>2</SUB>)<SUB>2</SUB>NCH<SUB>2</SUB>Ph}Sn]<SUB>2</SUB>.

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Characterisation of Bi<SUB>2</SUB>O<SUB>3</SUB>-, V<SUB>2</SUB>O<SUB>5</SUB>- and Pr<SUB>6</SUB>O<SUB>11</SUB>-doped ZnO varistor systems has been undertaken in this study. Bi<SUB>2</SUB>O<SUB>3</SUB>-, V<SUB>2</SUB>O<SUB>5</SUB>- and Pr<SUB>6</SUB>O<SUB>11 </SUB>are categorised as varistor formers, and without them ZnO will not exhibit varistor behaviour. The samples were prepared by conventional mixed-oxide ceramic technology. A variety of analytical techniques including X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used in this study. The electrical properties of the materials were characterised by their current-voltage behaviour. The investigation of each varistor system could be considered individually with its own objectives in order to gain a better understanding of each system. The research is also aimed at a comparison of the behaviour of the relatively new ZnO-V<SUB>2</SUB>O<SUB>5</SUB> system and the less characterised ZnO-Pr<SUB>6</SUB>O<SUB>11</SUB> system with the extensively studied ZnO-Bi<SUB>2</SUB>O<SUB>3</SUB> system. The investigation of the ZnO-Bi<SUB>2</SUB>O<SUB>3</SUB> system was based on the study of a multi-component system containing Sb<SUB>2</SUB>O<SUB>3</SUB>, MnO<SUB>2</SUB> and Co<SUB>3</SUB>O<SUB>4</SUB> cooled at different rates from a sintering temperature of 1200°C. The different cooling rates affected the electrical properties significantly. These could be explained in terms of the microstructure changes, particularly with respect to the different Bi-rich phases present. Fast cooling resulted in a decrease in the non-linear coefficient, α. In addition, the characterisation of the faceting at ZnO-δ-Bi<SUB>2</SUB>O<SUB>3</SUB> interphase boundaries in the water-quenched specimens provided an insight to the anisotropic growth of ZnO during the sintering process. An attractive feature of the ZnO-V<SUB>2</SUB>O<SUB>5</SUB> system is that the ceramic can be sintered at a relatively low temperature of ˜ 900°C. The effects of additive oxides (MnO<SUB>2</SUB>, Co<SUB>3</SUB>O<SUB>4</SUB> and Sb<SUB>2</SUB>O<SUB>3</SUB>) commonly found in Bi<SUB>2</SUB>O<SUB>3</SUB>- doped ZnO varistor systems were studied in a ZnO - 0.25 mol% V<SUB>2</SUB>O<SUB>5</SUB> system. The addition of MnO<SUB>2</SUB> significantly improved the varistor behaviour. Although the system containing all the different additives produced the best varistor behaviour, the addition of Sb<SUB>2</SUB>O<SUB>3</SUB> retarded the sintering process and a sintering temperature ≥ 1200°C had to be used. The varistor behaviour could also be improved by increasing the V<SUB>2</SUB>O<SUB>5</SUB> content to 0.5 mol%. α-, β- and γ-Zn<SUB>3</SUB>(VO<SUB>4</SUB>)<SUB>2</SUB> polymorphs as suggested by Brown and Hummel (1965) were detected in the samples as a secondary phase using XRPD.

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