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Author: Richard P. Rose
Publisher:
ISBN:
Category : Gallium
Languages : en
Pages : 312
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Author: Richard P. Rose
Publisher:
ISBN:
Category : Gallium
Languages : en
Pages : 312
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Author: Jiaye Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 410
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This thesis concerns research into the synthesis of low oxidation state group 14 complexes and their reactivity towards small molecule activation. A number of group 14 complexes in the +1 or +2 oxidation states have been synthesized. These include the first singly-bonded amido germanium(I) complex (amido-digermyne, [LGeGeL], L = {N(MeAr)(SiMe3)}, MeAr = C6H2{C(H)Ph2}2Me-2,6,4), amido group 14 metal(II) halide complexes, e.g. [LECl] (E = Ge, Sn or Pb, SiR3 = SiMe3, SiPh2Me or SiPh3), and amido silicon(IV) halide complexes, e.g. [LSiX3] (X = Cl or Br). The reactivity of the amido digermyne towards a variety of small molecules, e.g. H2, CO2, N2O, CS2, alkynes, etc., has been examined. In addition, the synthesis of "one-coordinate" group 14 metal(II) monocationic complexes (e.g. [LE]+[PF]-, E = Ge or Sn, PF = [Al{OC(CF3)3}4]- ) has been investigated and their reactivity towards Lewis base molecules has been examined. Work included in this thesis can be divided into six chapters. Chapter 1 introduces recent developments in main group chemistry, bonding in low oxidation state main group compounds, kinetic stabilization, and the "inert pair" effect. Some examples of low oxidation state main group complexes are described.Chapter 2 introduces the synthesis and coordination chemistry of a series of bulky secondary amines, [(MeAr)(SiR3)NH], [(iPrAr)(SiMe3)NH] (iPrAr = C6H2{C(H)Ph2}2iPr-2,6,4) and [(tBuAr)(SiR3)NH] (tBuAr = C6H2{C(H)Ph2}2tBu-2,6,4). Subsequently, the chapter discusses the synthesis of amido group 14 metal(II) halide complexes, e.g. [LECl] (E = Ge, Sn or Pb; SiR3 = SiMe3, SiPh2Me or SiPh3), [{(iPrAr)(SiMe3)N}ECl] (E = Ge or Sn) and {(tBuAr)(SiMe3)N}GeCl. The structures of these complexes have been determined using X-ray crystallography. Furthermore, amido silicon(IV) halide complexes, [LSiX3] (SiR3 = SiMe3, SiPh2Me or SiPh3; X = Cl or Br) and [{(iPrAr)(SiR3)N}SiBr3], as well as an amido silicon hydride, [LSi(H)Cl2] have been synthesized and structurally investigated. Chapter 3 discusses the synthesis and structural characterization of the first singly-bonded amido-digermyne, [LGeGeL], and its reactivity towards small gas molecule activation, e.g. that of H2, CO2, N2O, etc. at ambient and low temperatures. These reactions produced bulky amido germanium(II) and germanium(III) hydride complexes, and a bis(germylene) oxide complex. Further efforts have been devoted to the reactivity of [LGeGeL] towards molecules such as CS2, tBuNC and tBuNCO. Chapter 4 expands on the reactivity of [LGeGeL] and [L#GeGeL#] (L# = (iPrAr)(SiiPr3)N). It describes reactions that have been carried out with organic molecules, e.g. cyclooctatetraene (COT), 4-dimethylaminopyridine (DMAP), azobenzene, 1,4-bis(trimethylsilyl)butadiyne, norbornadiene, etc. These reactions produced a number of low oxidation state germanium complexes. In general, the reactions of [LGeGeL] and [L#GeGeL#] with unsaturated molecules produced products with the substrate inserted into the Ge-Ge bond. However, the reaction with DMAP produced a bis-adducted germanium complex with a shortened Ge-Ge bond. Finally, reactions of [LGeGeL] with chlorinated compounds, iodine, and ketones are discussed. Chapter 5 summarizes investigations into the synthesis and coordination chemistry of the first examples of bulky amido "one-coordinate" germanium(II) and tin(II) monocationic complexes, [LE]+[PF]- (E = Ge or Sn, PF = [Al{OC(CF3)3}4]-) and [L'Sn]+[PF]- (L' = [(MeAr)(SiPh2Me)N]). Their reactivity towards DMAP was investigated, and this led to two-coordinate adducted germanium or tin cationic complexes. Chapter 6 summarizes miscellaneous results, and consists of two sections. The first section discusses theoretical investigations into the Mo-Ge bonding of singly-bonded or triply-bonded molybdenum germylene and germylyne complexes. Wiberg bond indices (WBI) were acquired to provide a quantitative description of the bonding in these complexes. The second section focuses on investigations into the synthesis of a bulky gallium(I) amide complex, [LGa:], which was prepared from the reaction of [{(MeAr)(SiMe3)N}Li] and "GaI". X-ray crystallographic studies of [LGa:] were carried out and indicate that the complex is essentially one-coordinate.
Author: Terrance John Hadlington
Publisher: Springer
ISBN: 3319518070
Category : Science
Languages : en
Pages : 256
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This outstanding thesis describes a detailed investigation into the use of low-oxidation-state group 14 complexes in catalysis, developed at the cutting edge of inorganic and organometallic chemistry. It includes the preparation of a number of landmark compounds, some of which challenge our current understanding of metal–metal bonding and low-oxidation-state main group chemistry. Among the many highlights of this thesis, the standout result is the development of the first well-defined, low- oxidation-state main group hydride systems as highly efficient catalysts in the hydroboration of carbonyl substrates, including carbon dioxide, which are as efficient as those observed in more traditional, transition-metal catalyses. These results essentially define a new subdiscipline of chemistry.
Author: William Douglas Woodul
Publisher:
ISBN:
Category :
Languages : en
Pages : 454
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This thesis is mainly concerned with investigations into the reactivity of the gallium(I) N-heterocyclic carbene (NHC) analogue, [K(tmeda)][:Ga{[N(Dip)C(H)]2}] (Dip = C6H3Pri2-2,6). The preparation of the first monomeric Ge(I) radical was also investigated. Work carried out in these areas is divided into five chapters. Chapter 1 provides a general introduction to sub-valent group 13 and 14 chemistry, with an emphasis on the preparation of group 13 metal(I) and group 14 metal(II) N-heterocyclic carbene analogues. Chapter 2 summarizes investigations into the reactivity of [K(tmeda)] [:Ga{[N(Dip)C(H)]2}] towards groups 2 and 12 metal precursors. Reactions of magnesium, calcium, strontium, barium, zinc, and cadmium halides with [K(tmeda)][:Ga{[N(Dip)C(H)]2}] are discussed, and the first structurally characterized cadmium-gallium bonded molecular complex is reported. Chapter 3 summarizes investigations into the reactivity of [K(tmeda)] [:Ga{[N(Dip)C(H)]2}] towards selected lanthanide metal precursors. Reactions of samarium(II), europium(II), ytterbium(II), thulium(II), and cerium(III) iodides with [K(tmeda)][:Ga{[N(Dip)C(H)]2}] have given rise to a number of novel lanthanide-gallyl species, including the first structurally characterized GaTm or GaSm bonded complexes. Chapter 4 details the preparation of the first monomeric Ge(I) radical via the reduction of a bulky [beta]-diketiminato germanium(II) precursor. The verification of the +1 oxidation state in this species was achieved using a combination of crystallographic, EPR and ENDOR spectroscopic, and theoretical analyses. Chapter 5 describes several miscellaneous results, largely derived from attempts to prepare bulky guanidinato complexes of p-block elements in low oxidation states.
Author: Marc Kloth
Publisher:
ISBN:
Category : Complex compounds
Languages : en
Pages : 388
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Author: Audra Faye Lugo
Publisher:
ISBN:
Category : Chelates
Languages : en
Pages :
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Author: Simon James Bonyhady
Publisher:
ISBN:
Category :
Languages : en
Pages : 594
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This thesis pertains to the synthesis and stabilisation of low oxidation state main group element complexes through the utilisation of novel magnesium(I) dimers as reducing agents. As such, it is an exploration of the utility of these magnesium(I) complexes in organometallic synthesis and has resulted in the isolation of a number of compounds featuring unusual structural motifs, oxidation states and bonding modes.Chapter 1 provides a general introduction to low oxidation state main group chemistry and discusses a number of concepts that are unique to this field of study. Particular attention is paid to historical concepts such as the "double bond rule" and the new understanding of chemical bonding that has developed as a result of this "renaissance" in main group chemistry, as well as a general discussion of synthetic methods to access these compounds.Chapter 2 introduces the magnesium(I) dimers reported to date and details both their synthesis and reactivity in organic and organometallic synthesis. Two new [beta]-diketiminato magnesium(I) complexes are described, along with their [beta]-diketiminato magnesium(II) halide precursor complexes, and efforts towards improving the synthesis of these unusual compounds are outlined. A number of other novel [beta]-diketiminato magnesium(II) hydride, alkyl and halide complexes are also presented. Finally, efforts towards the synthesis of soluble models of magnesium amido-boranes, in which this library of magnesium(I and II) complexes is exploited, are also discussed.Chapter 3 presents a case study into the utility of magnesium(I) dimers as reducing agents in organometallic synthesis. A series of amidinato group 14 element(I) dimers [LEEL] (E = Si, Ge, Sn; L = amidinate) were synthesised in high to moderate yield, and comparisons between the magnesium(I) dimers and traditional reducing agents emphasised the efficacy of the magnesium(I) dimers in this role. The tin compound is the first of its type, while one and two previous examples exist for the silicon and germanium complexes, respectively, although they were only isolated in low yield.Chapter 4 describes the development of low oxidation state aluminium hydride chemistry, an area in which magnesium(I) dimers have been instrumental. A number of novel compounds are presented including of a series of compounds which feature remarkable [Al6H6] octahedral cores.Chapter 5 details efforts to extend the use of magnesium(I) dimers to compounds stabilised by bulky terphenyl ligands. The preparation of the second example of a diplumbyne, for which a moderate yielding synthesis was determined, is described. A dialumene and a disilyne were also desirable synthetic targets, and efforts to these ends are also outlined.Finally, Chapter 6 provides a summary of the results presented in this thesis.
Author: María Viviana Lomelí Tapuach
Publisher:
ISBN:
Category : Oxidation
Languages : en
Pages : 292
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Author: Bobby Dean Ellis
Publisher:
ISBN:
Category :
Languages : en
Pages : 478
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Author: Madison Louis McCrea-Hendrick
Publisher:
ISBN: 9780438627642
Category :
Languages : en
Pages :
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This dissertation describes the synthesis, characterization and reactivity of some low-coordinate, low-oxidation state heavier main group 13 and 14 element species. Chapter 2 describes the reactivity of the heavier main group 13 element digallene, (GaAr[superscript iPr4])2, (Ar[superscript iPr4] = -C6H3-2,6-(C6H3-2,6-[superscript i]Pr2)2) with group 6 transition metal hexacarbonyls under photoirradiation to form the bis(gallanediyl) complexes, trans-bis(GaAr[superscript iPr4])2M(CO)4 (M = Cr, Mo, or W). The mechanism of formation of these products was investigated both computationally and experimentally. A postulated intermediate in their formation is the monogallanediyl complex, Ga(Ar[superscript iPr4])Mo(CO)5 which was synthesized by the reaction (GaAr[superscript iPr4])2 with two equivalents Mo(CO)5NMe3. (GaAr[superscript iPr4])2 was also reacted at 25°C with Co2(CO)8 to give Ga(Ar[superscript iPr4])Co2(CO)7, in which the gallanediyl fragment is bound to each cobalt atom in a bridging fashion. Chapter 3 is an extension of the work in Chapter 2 to the reactions of the heavier main group 14 element dimetallynes, (EAr[superscript iPr4])2 (E = Ge or Sn), with group 6 transition metal hexacarbonyls under photoirradiative conditions. These reactions afforded the products {Ar[superscript iPr4]EM(CO)4}2 (E = Ge or Sn; M = Cr, Mo, or W) which featured rhomboid E2M2 cores with Ar[superscript iPr4]E units bridging transition metal tetracarbonyl fragments, M(CO)4. Chapter 4 describes the reactions of the aryl tin(II) hydrides {Ar[superscript iPr6]Sn([mu]-H)}2 (Ar[superscript iPr6] = C6H3-2,6-(C6H2-2,4,6-[superscript i]Pr6)2) and {Ar[superscript iPr4]Sn([mu]-H)}2 with phenyl acetylene and diphenyl acetylene. The reactions with diphenyl acetylene affords simple insertion of the Sn-H bond into a [pi]-bond of the alkyne to yield the products ArSnC(Ph)C(H)Ph (Ar = Ar[superscript iPr6] or Ar[superscript iPr4]). In contrast, the reaction of {ArSn([mu]-H)}2 with phenyl acetylene affords different products that are connected with the presence (Ar[superscript iPr6]) or absence (Ar[superscript iPr4]) of an isopropyl group at the remote para position of the flanking aryl rings of the terphenyl substituent. When {Ar[superscript iPr6]Sn([mu]-H)}2 is reacted with phenyl acetylene the product Ar[superscript iPr6](H)SnC(H)C(Ph)Sn(H)Ar[superscript iPr6] containing a 1,2-distannacyclobut-3-ene moiety is obtained as a colorless solid. In contrast, the reaction of {Ar[superscript iPr4]Sn([mu]-H)}2 with phenyl acetylene affords a red product of formula Ar[superscript iPr4]SnC(H)C(Ph)Sn(H)2Ar[superscript iPr4] with the tin atoms having different oxidation states of +2 and +4 as determined by solution 119Sn NMR spectroscopy. Chapter 5 describes the synthesis and characterization of the most sterically congested tetrylenes currently known: E(Ar[superscript iPr6])2 (E = Ge, Sn, or Pb). Computational studies of these tetrylenes and E(Ar[superscript Me6])2 (Ar[superscript Me6] = C6H3-2,6-(C6H2-2,4,6-Me3)2) and E(Ar[superscript iPr4])2 were also performed with and without dispersion corrections to evaluate the contribution of London dispersion force effects on the C[subscript ipso]-E-C[subscript ipso] interligand angle.
