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Synthetic inorganic chemistry : novel metallocenes and inorganic fullerenesClancy, Gerald Patrick January 2000 (has links)
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(C<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PMe<sub>2</sub>] (M = H, Li, Na and K) via the precursors [HC<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PHMe<sub>2</sub>][X] (X = Cl and PF<sub>6</sub>). The synthesis, characterisation and chemical reactivity of the compounds [Zr{{η-C<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PMe<sub>2</sub>}<sub>2</sub>Cl<sub>2</sub> and [Mn{η-C<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PMe<sub>2</sub>}<sub>2</sub>] is reported together with supporting evidence for the synthesis of the bimetallic complex [Zr{U+03B7-C<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PMe<sub>2</sub>}<sub>2</sub>Cl<sub>2</sub>PtI<sub>2</sub>] and the complex [Mn{η-C<sub>5</sub>Me<sub>4</sub>)CH<sub>2</sub>PMe<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>}<sub>2</sub>]. <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- C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>PMe<sub>2</sub>}<sub>2</sub>] (M = Pb and Sn). The B(C<sub>6</sub>F<sub>5</sub>)<sub>3 adduct [Pb{η-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>PMe<sub>2</sub>(B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>}<sub>2</sub>] has also been synthesised. The main group - transition metal bimetallic complex [Pb{η-C<sub>5</sub>H<sub>4</sub>)CMe<sub>2</sub>PMe<sub>2</sub>}<sub>2</sub>PtI<sub>2<sub> in which the substitutedplumbocene acts as a bidentate ligand, has been characterised by mass spectrometry and <sup>31</sup>P{<sup>1</sup>H}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-MoS<sub>2</sub> and IF-(Nb,W)S<sub>2</sub> materials from MoC and the binary oxides Nb<sub>8</sub> W<sub>9</sub>O<sub>47</sub> and Nb<sub>4</sub>W<sub>13</sub>O<sub>47</sub> respectively. A powder X-ray diffraction study of the conversion of WC to WO<sub>3-X</sub> and the subsequent sulfidisation by H<sub>2</sub>S to form novel IF-WS<sub>2</sub> 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-V<sub>2</sub>O<sub>3</sub>, NbO<sub>2</sub> and TT-Ta<sub>2</sub>O<sub>5</sub> which have been identified by powder X-ray diffraction. Upon reaction with H<sub>2</sub>S, the crystalline oxides afford layered sulfides of the form MS<sub>2</sub> (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-C<sub>5</sub>Me<sub>4</sub>)CH<sub>PMe<sub>2</sub>}<sub>2</sub>].
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[en] SYNTHESIS AND CHARACTERIZATION OF LOW THERMAL EXPANSION OXIDES / [pt] SÍNTESE E CARACTERIZAÇÃO DE ÓXIDOS COM BAIXA EXPANSÃO TÉRMICAMONICA ARI SANO 19 February 2008 (has links)
[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.
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