Item – Thèses Canada

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Numéro d'OCLC
46558957
Auteur
Gossage, Robert Arthur,1965-
Titre
Phosphinoalkylsilyl chemistry : tripodal and mesmolecular complexation.
Diplôme
Ph. D. -- University of Victoria, 1996
Éditeur
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [1998]
Description
3 microfiches.
Notes
Includes bibliographical references.
Résumé
The preparation of the modified silane $\rm\lbrack Ph\sb2P(CH\sb2)\sb3\rbrack\sb2SiRH\ (R = CH\sb3;$ a phosphinoalkylsilane or PSi) via an alkylzirconium intermediate is reported. The synthesis of $\rm\lbrack Ph\sb2P$(o-$\rm C\sb6H\sb4CH\sb2)\rbrack\sb{n}SiR\sb{3-n}H\ (R = CH\sb3, n = 1{-}3)$ and o-$\rm Ph\sb2PCH\sb2C\sb6H\sb4Si(CH\sb3)\sb2H$ was carried out by the reaction of organolithium reagents with chloro-silanes at low temperature. The PSi compounds are isolated as air-sensitive, thermally stable and very viscous liquids. The reactivity of two of the silanes was investigated with the platinum group metal complex Pt(cod)Cl$\sb2$ (cod = cycloocta-1,5-diene). In both cases, square planar platinum (II) complexes were isolated. The reactivity of $\rm\lbrack Ph\sb2P(CH4\sb2)\sb3\rbrack\sb2SiRH$ and $\rm\lbrack Ph\sb2P$(o-$\rm C\sb6H\sb4CH\sb2)\rbrack\sb2SiRH$ (R = CH$\sb3)$ with $\rm\lbrack M(cod)Cl\rbrack\sb2$ (M = Rh or Ir) produces five coordinate M (III) complexes which undergo stereomutation. The isomerisation of the syn to anti forms of $\rm MH\lbrack Si(Me)\{(CH\sb2)\sb3PPh\sb2\}\sb2\rbrack\sb2$ (M = Rh) has been examined at several temperatures via NMR spectroscopy and the activation parameters determined for the conversion of the syn to the intermediate isomer form $\rm(\Delta G\ddagger=95$ (4) kJmol$\sp{-1},\ \Delta H\ddagger=71$ (2) kJmol$\sp{-1}$ and $\rm\Delta S\ddagger={-}82$ (7) JKI$\sp{-1}$mol$\sp{-1}).$ The implications of the stereomutation phenomona are discussed in relation to catalysis. None of the isomers of this complex forms a stable six coordinate adduct when reacted with a number of common nucleophiles. The analogous compound where M = Ir and related complexes of the formula $\rm MH\lbrack Si(Me)\{CH\sb2C\sb6H\sb4PPh\sb2\}\sb2\rbrack Cl$ (M = Rh or Ir) are reactive towards CO to form stable six coordinate adducts containing two M-P and one M-Si, M-H, M-CO and a M-Cl bond. Some of these adducts can be made directly by the reaction of the PSi ligand precursor with $\rm M(PPh\sb3)\sb2Cl(CO)$ (M = Rh, Ir) at room temperature. The reaction of the silane $\rm\lbrack Ph\sb2P$(o-$\rm C\sb6H\sb4CH\sb2)\rbrack\sb3SiH$ with $\rm\lbrack M(cod)Cl\rbrack\sb2$ (M = Rh or Ir) produces six coordinate complexes directly. For M = Ir, the compound reacts with CO to produce a six coordinate cation by displacement of a chloride ligand, the latter of which then acts as a non-coordinating counterion. A series of organosilicon dendrimers of the type: $\rm PhSi\lbrack(CH\sb2)\rbrack\sb3\lbrack Si(CH\sb2)\sb3\rbrack\sb{q}\{Si(CH\sb2)\sb3\}\sb{z}(Si(CH\sb2)\sb3)\sb{y}{\langle}Si(C\sb3H\sb5)\sb3{\rangle}\sb{x}$ ( (G-1): x = 3, y = z = q = 0; (G-2): y = 3, x = 9, z = q = 0; (G-3): z = 3, y = 9, x = 27, q = 0; (G-4): q = 3, z = 9, y = 27, x = 81) are sythesised and examined spectroscopically. All of the dendrimers are air stable liquids. Species G3 has a marked tendency to undergo what appears to be self-condensation polymerisation. End and core group substitution is presented for a carbosilane dendrimer containing one shell of identical exterior Si atoms. The dendrimeric end groups can be modified by the replacement of a terminal chloride by fluoride, hydrogen, alkyl groups or metal complexes. The selective removal of a core phenyl group can be accomplished with the strong acid $\rm CF\sb3SO\sb3H.$ The resulting silyl triflate can in turn be used as a precursor to a silyl ether, hence facilitating selective core group modification.
ISBN
0612219321
9780612219328