This thesis is divided into two parts. The first part concerns the synthesis and characterisation of substituted metallocene complexes of the transition and main group metals. The second part describes the preparation and characterisation of inorganic fullerene (IF)-related materials. <strong>Chapter 1</strong> reviews the chemistry of dialkyl- and diaryl-phosphino substituted cyclopentadienyl complexes of the transition metals. <strong>Chapter 2</strong> describes the synthesis and characterisation of the new ligands [M(C₅Me₄)CH₂PMe₂] (M = H, Li, Na and K) via the precursors [HC₅Me₄)CH₂PHMe₂][X] (X = Cl and PF₆). The synthesis, characterisation and chemical reactivity of the compounds [Zr{{η-C₅Me₄)CH₂PMe₂}₂Cl₂ and [Mn{η-C₅Me₄)CH₂PMe₂}₂] is reported together with supporting evidence for the synthesis of the bimetallic complex [Zr{U+03B7-C₅Me₄)CH₂PMe₂}₂Cl₂PtI₂] and the complex [Mn{η-C₅Me₄)CH₂PMe₂B(C₆F₅)₃}₂]. <strong>Chapter 3</strong> provides a brief introduction into the field of main group metallocenes and describes the synthesis and characterisation of the new main group metallocenes [M{η- C₅H₄)CMe₂PMe₂}₂] (M = Pb and Sn). The B(C₆F₅)<sub>3 adduct [Pb{η-C₅H₄)CMe₂PMe₂(B(C₆F₅)₃}₂] has also been synthesised. The main group - transition metal bimetallic complex [Pb{η-C₅H₄)CMe₂PMe₂}₂PtI<sub>2<sub> in which the substitutedplumbocene acts as a bidentate ligand, has been characterised by mass spectrometry and ³¹P{¹H}NMR spectroscopy. <strong>Chapter 4</strong> provides an introduction into the field of IF-related materials and an overview of the analytical techniques used in their characterisation. <strong>Chapter 5</strong> describes the preparation and characterisation of IF-MoS₂ and IF-(Nb,W)S₂ materials from MoC and the binary oxides Nb₈ W₉O₄₇ and Nb₄W₁₃O₄₇ respectively. A powder X-ray diffraction study of the conversion of WC to WO_3-X and the subsequent sulfidisation by H₂S to form novel IF-WS₂ morphologies is also described. <strong>Chapter 6</strong> describes the preparation of amorphous Group 5 metal (V, Nb and Ta) oxides using the metal vapour synthesis technique. These amorphous precursors have been annealed in a reducing atmosphere to form the oxide phases U+03B1-V₂O₃, NbO₂ and TT-Ta₂O₅ which have been identified by powder X-ray diffraction. Upon reaction with H₂S, the crystalline oxides afford layered sulfides of the form MS₂ (M = V, Nb and Ta), some of which exhibit behaviour typical of IF-like materials and have been characterised by HRTEM, powder X-ray diffraction and EDX analysis. Chapter 7 outlines the experimental details for the synthesis, characterisation, reactions and compounds described in the preceding chapters. <strong>Chapter 8</strong> presents the characterising data for the new compounds described in chapters 2 and 3. <strong>Appendix A</strong> contains details of the crystallographic data for the structurally characterised compound [Mn{η-C₅Me₄)CH<sub>PMe₂}₂].

[pt] Materiais que apresentam expansão térmica baixa ou negativa possuem grande potencial de emprego em diversas aplicações que requerem resistência ao choque térmico, assim como para aplicações odontológicas, em placas de circuitos eletrônicos, em componentes ópticos e para produzir compósitos em que compensam a expansão térmica positiva de outros materiais. Por este motivo, o estudo e a produção de materiais com expansão térmica controlada têm crescido nos últimos anos. No presente trabalho, foram estudadas algumas famílias de óxidos com estruturas que apresentam este tipo de comportamento. Foi avaliada a expansão térmica em três sistemas da família A2M3O12 com o intuito de produzir materiais com expansão térmica controlada pela substituição química do cátion A pelos cátions Al, Cr e Fe. Os sistemas produzidos foram: Cr2xFe2-2xMo3O12 (molibdato de cromo - ferro), Al2xCr2- 2xMo3O12 (molibdato de alumínio - cromo) e Al2xFe2-2xMo3O12 (molibdato de alumínio - ferro). Além destes, o composto HfMgMo3O12 foi também sintetizado para testar a viabilidade de substituição dos cátions A trivalentes por um cátion divalente e um tetravalente. Foi possível obter soluções sólidas monofásicas e seus parâmetros de rede variam linearmente com o aumento no conteúdo do cátion de maior tamanho, conforme a lei de Vegard. Análise térmica realizada por DSC permitiu determinar a temperatura de transição de fase da estrutura monoclínica (P21a) à ortorrômbica (Pbcn). Os valores encontrados foram: para o Al2Mo3O12, 200oC, para o Cr2Mo3O12 , 403oC e para o Fe2Mo3O12, 512oC. Coeficientes de expansão térmica intrínsecos foram determinados por difração de raios-X utilizando luz síncrotron, encontrando-se valores bem reduzidos para todos os sistemas estudados, a saber: para o Al2Mo3O12, (alfa)l = 2,32 x 10- 6/oC, para o Cr2Mo3O12 , (alfa)l = 0,65 x 10-6/oC e para o Fe2Mo3O12, (alfa)l = 1,72 x 10-6/oC. / [en] Negative and low thermal expansion materials have important potential applications as resistance to thermal shock, as well as, for odontological applications, printed circuit boards, optical components and to produce composites to compensate the positive thermal expansion of materials. For this reason, the study and production of materials with controlled thermal expansion have increased in the recent years. In the present work, some oxide families with structures that present this type of behavior were investigated. The thermal expansion in three systems of A2M3O12 family was evaluated in order to produce materials with controlled thermal expansion through the chemical substitution of cation A with Al, Cr and Fe. The produced systems were: Cr2xFe2-2xMo3O12 (chromium - iron molybdate), Al2xCr2-2xMo3O12 (chromium - aluminum molybdate) and Al2xFe2-2xMo3O12 (aluminum - iron molybdate). Besides that, HfMgMo3O12 was synthesized to test the viability of substitution of trivalent cations for one divalent plus one tetravalent. It was possible to obtain single- phase solid solutions and their lattice parameters increased linearly with the increase of the largest cation content, following the Vegard`s law. Thermal analysis carried out by DSC allowed the determination of the phase transition temperature from monoclinic (P21a) to orthorhombic (Pbcn) structure. The values were 200oC for Al2Mo3O12, , 403oC for Cr2Mo3O12 , and 512oC for Fe2Mo3O12. Intrinsic thermal expansion coefficients were determined by X-rays diffraction using syncrotron radiation, and low values were found for all studied systems: (alfa)1 = 2,32 x 10- 6/oC for Al2Mo3O12, (alfa)1 = 0,65 x 10-6/oC for Cr2Mo3O12 , and (alfa)1 = 1,72 x 10-6/oC for Fe2Mo3O12.