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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
311

The chemistry of phosphoranoimino and 1-azaallyl group 4 and 14 metal complexes. / CUHK electronic theses & dissertations collection

January 2006 (has links)
Chapter 1 provides the general review of phosphoranoimines and 1-azaallyls as ligands for group 4 and 14 metal complexes. / Chapter 2 describes the development of low-valent group 14 1,3-dimetallacyclobutanes from phosphoranoimines. Three low-valent 1,3-distannacyclobutanes 1,3-[Sn{C(Pr i2P=NSiMe3)(2-Py)}]2 ( 95), 1,3-[Sn{C(Ph2P=NSiMe3)(C6H 5)}]2 (97) and 1,3-[Sn{C(Ph2P=NSiMe 3)(PPh2)}]2 (100) were synthesized from the phosphoranoimine ligands [CH2(Pri 2P=NSiMe3)(2-Py)] (92), [CH2(Ph 2P=NSiMe3)(C6H5)] (96) and [CH2(Ph2P=NSiMe3)(PPh 2)] (99), respectively. A novel cationic tin(IV) species [HC(Pri2P=NSiMe3)(Ar)] -[SnCl3]+ (Ar = 9-anthryl) ( 104) was synthesized from [CH2(Pri 2P=NSiMe3)(Ar)] (Ar = 9-anthryl) (103). / Chapter 3 describes the reactivies of low-valent group 14 1,3-distannacyclobutanes (95 and 111) and the isolation of the enantiomers of 95 and [1-Sn{C(Pri2P=NSiMe 3)(2-Py)}3-Pb{C(Pri2P=NSiMe 3)(2-Py)}] (120). The reactions of 95 or 111 with M(CO)5(THF) (M = Cr, Mo, W), CpMn(CO)2THF (Cp = eta-C5H5), MeI and Br2 were performed. Three isomers of compound 95 (95R, 95S and 95I) and two enantiomers of compounds 120 ( 120R and 120S) and 122 (122R and 122S) were obtained by the method of recrystallization from different solvents. Heteroleptic lead(II) compound [{(Pri 2P=NSiMe3)(2-Py)CH}Pb{N(SiMe3)2} 2] (121) was synthesized, which further react with 94 to give 1,3-[Pb{C(Pri2P=NSiMe 3)(2-Py)}]2 (122). / Chapter 4 describes the development of group 4 metal complexes from phosphoranoimines. Group 4 metal imido complexes [(Me2N)2M{CH(Ph2 PN)(2-Py)}]2 (M = Zr (133), Hf (134)) and ionic compounds [ML2Cl]+2[MCl 6]2- (L = {CH(R2PNSiMe3)(2-Py)}) (135 M = Zr, R = Ph, 136 M = Hf, R = Ph, 137 M = Zr, R = Pri, 138 M = Hf, R = Pri) were synthesized. The neutral zirconium(IV) dichloride compound [ZrCl2{CH(Ph2P=NSiMe 3)(C6H5)}2] (139) was prepared by the reaction of lithium compound [(THF)2Li{CH(Ph 2PNSiMe3)(C6H5)}] (97) with ZrCl4. The catalytic activity of the compounds toward ethylene polymerization has been investigated. / Chapter 5 describes the development of group 4 metal complexes from 1-azaallyls. Lithium cyclohexenyl-1-azaallyl compound [(TMEDA)LiN(SiMe3)C(Ph)= CHCHC&parl0;SiMe3&parr0;CH2CH 2C H2] (149) and zirconium(IV) dichloride compound [Zr{N(SiMe3)C(Ph)(L)}2Cl2] (L = CHCHC&parl0;SiMe3&parr0;CH2CH 2C H2) (150) were synthesized. Novel anionic one-dimensional bifunctional lithium compound [{(THF)Li(N(SiMe3))2C}(CN)C 6H4-1,4)]n (151) has also been synthesized. Similar reactions of 1,2-dicyanobenzene, 1,3-dicyanobenzene or 1,4-dicyanobenzene with lithium amide [(Et2O)2LiN(SiMe3) 2] afforded lithium bis(1,3-diazaallyl) compounds [{(THF)2Li(N(SiMe 3))2C}C6H4-1,2)] (152), [{(THF)2Li(N(SiMe3))2C}C6H 4-1,3)] (153) and [{(THF)2Li(N(SiMe3)) 2C}C6H4-1,4)] (154), respectively. / The work presented in this thesis is mainly focused in two parts: (i) the synthesis and reactivities of low-valent main group 14 metal complexes derived from phosphoranoimines, (ii) the synthesis and catalytic studies of transition group 4 metal complexes derived from phosphoranoimines and 1-azaallyl ligands. / Wong Kam Wing. / "December 2006." / Adviser: Kevin Wing-Por Leung. / Source: Dissertation Abstracts International, Volume: 68-08, Section: B, page: 5233. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
312

Investigation and application of aryl carbon-halogen bond cleavage with rhodium and iridium porphyrin complexes.

January 2014 (has links)
本論文主要研究銥和銠卟啉絡合物與鹵代苯 (ArX, X = Cl, Br, I)的碳-鹵鍵(Ar-X)的斷裂反應及其應用。本論文分為四個部分:(1)銠卟啉絡合物與鹵代苯(ArX, X = Cl, Br, I)之間的碳-鹵鍵(Ar-X)斷裂反應;(2)氟氯化苯的碳-氟鍵(Ar-F)與碳-氯鍵(Ar-Cl)斷裂的競爭反應;(3)氟取代基對金屬(銥和銠)-芳香碳(M-Ar)鍵強弱的影響;以及(4)銥卟啉氟硼荧絡合物的合成。 / 第一部分闡述了銠卟啉絡合物(Rh(ttp)Cl)與鹵代苯(ArX, X = Cl, Br, I) 之間的碳-鹵鍵 (Ar-X) 斷裂反應以及反應機理。在鹼性條件下,無論富電子還是缺電子的鹵代苯都能與Rh(ttp)Cl反應,生成Ar-X鍵斷裂的產物──銠卟啉芳基絡合物(Rh(ttp)Ar) 。機理研究顯示, Rh(ttp)Cl 首先與氫氧根離子反應生成Rh(ttp)OH,進而通過二聚反應生成[Rh(ttp)]₂。[Rh(ttp)]₂在加熱條件下與Rh(ttp)自由基可以互相轉化,產生的Rh(ttp)自由基與鹵代苯進行原位取代反應,生成銠卟啉芳基絡合物(Rh(ttp)Ar)和鹵素自由基。鹵素自由基可以和另一個Rh(ttp)自由基反應生成Rh(ttp)X,在氫氧根離子存在的條件下,Rh(ttp)X將再次轉化為Rh(ttp)OH繼續反應。 / 第二部分描述了氟氯化苯中碳-氟鍵(Ar-F)與碳-氯鍵(Ar-Cl)斷裂的競爭反應。機理研究顯示碳-氟鍵(Ar-F)斷裂的中間體是M(por)⁻,而碳-氯鍵(Ar-Cl)斷裂的中間體是MII(por)。因此,我們可以通過改變反應條件而控制生成物。例如,在較低溫度下和強鹼性的極性溶劑中,以M(por)⁻前體作為反應物,可以獲得較多的碳-氟鍵(Ar-F)斷裂的產物;而在較高溫度下和弱鹼性的非極性溶劑中,可以獲得較多的碳-氯鍵(Ar-Cl)斷裂的產物。 / 第三部分敘述了間位氟取代基對金屬-芳香碳(M-Ar)鍵的增強作用。有間位氟取代基的金屬(銥,銠)卟啉芳基絡合物(M(ttp)ArF)是最穩定的同分異構體。在250°C條件下,當反應30天後,Ir(ttp)C₆H₄F的三個異構體達到平衡狀態,其鄰位:間位:對位的比例大約為0:5:1。理論計算的結果也顯示Ir(ttp)(3-fluorophenyl)相對Ir(ttp)(2-fluorophenyl)和Ir(ttp)(4-fluorophenyl)有更低的能量。氟取代基在鄰位時,氟與卟啉之間空間位阻較大,減弱了金屬-芳香碳(M-Ar)鍵的鍵能。與氟取代基在對位相比,在間位時具有更好的吸電子效應,從而增加了金屬-芳香碳(M-Ar)鍵的極性,增強了金屬-芳香碳(M-Ar)鍵鍵能。 / 第四部分描述了利用碳-鹵鍵 (Ar-X) 的斷裂,合成銥卟啉氟硼荧絡合物的反應。銥卟啉氟硼荧絡合物的產率可以達到70%。銥卟啉氟硼荧絡合物在生物成像和放射療法都有潛在的應用。銥卟啉氟硼荧絡合物是用金屬自由基與氟硼荧反應合成的。 / This thesis focuses on the reaction scopes, mechanistic investigations and applications of base-promoted aryl carbon-halogen (Ar-X) bond cleavage with iridium and rhodium porphyrin complexes. This thesis is divided into four parts: (1) Ar-X (X = Cl, Br, I) bond cleavage with Rh(ttp)Cl; (2) competitive Ar-F and Ar-Cl bond cleavage with iridium and rhodium porphyrins; (3) fluorine substituent effect on the M-Ar (M = Ir, Rh) bond strength; and (4) synthesis of iridium porphyrin BODIPY complexes. / Part I describes the reaction scopes and mechanism of Ar-X (X = I, Br, Cl) bond cleavage with Rh(ttp)Cl (ttp = 5,10,15,20-tetratolylporphyrinato dianion). Under basic conditions, both electron-rich and electron-deficient ArX undergo Ar-X bond cleavage to give Rh(ttp)Ar in good yields. [with diagram] / The mechanistic investigations suggest that RhIII(ttp)Cl first undergoes ligand substitution by OH- to give RhIII(ttp)OH, which forms [RhII(ttp)]₂ through reductive dimerization. RhII(ttp) radical, which is in equilibrium with [RhII(ttp)]₂, cleaves the Ar-X (X = I, Br, Cl) bond through metalloradical ipso-substitution and gives RhIII(ttp)Ar and X radical. X radical recombines with another RhII(ttp) radical to generate RhIII(ttp)X, which gives back RhIII(ttp)OH through ligand substitution by OH-. [with diagram] / Part II describes the competitive Ar-F and Ar-X (X = Cl, Br) bond cleavage reactions of fluorochlorobenzenes with iridium and rhodium porphyrin complexes. Mechanistic studies suggest that M(por)⁻ is the intermediate for the Ar-F bond cleavage while MII(por) is the intermediate for the Ar-X bond cleavage. By taking advantage of the difference in mechanisms of the Ar-F and Ar-X bond cleavages, the selectivity of bond cleavage can be controlled by varying the reaction conditions. The Ar-F bond cleavage is favored in a polar solvent with a stronger base at lower temperatures with M(por)⁻ precursor, and the Ar-X bond cleavage is favored under non-polar conditions with a weaker base and at higher temperatures. [with diagram] / Part III describes the meta-fluorine substituent effect on strengthening the M-Ar (M = Ir, Rh) bond of M(ttp)ArF. M(ttp)ArF with meta-fluorine substituent are the most stable isomers among the isomeric Ar-H bond cleavage products. At 250 °C for 30 days, the three isomers of Ir(ttp)C₆H₄F reached an equilibrium with o : m : p = 0 : 5 : 1. The theoretical calculations also suggest that Ir(ttp)(3-fluorophenyl) is of lower energy than Ir(ttp)(2-fluorophenyl) and Ir(ttp)(4-fluorophenyl). The ortho-fluorine substituent exhibits steric effect which weakens the M-Ar bond. The meta-fluorine, which is more electron-withdrawing than para-fluorine, enhances the polarity of the M-C(ipso) bond and thus strengthens the M-Ar bond. [with diagram] / Part IV describes the application of Ar-I bond cleavage with Ir(ttp)(CO)Cl in synthesizing iridium porphyrin boron-dipyrromethene (BODIPY) complexes, which are potential photosensitizers for biological imaging and photodynamic therapy. The clinically interested iridium porphyrin BODIPY complexes have been prepared by a radical process of metalloradical with BODIPY. [with diagram] / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Qian, Yingying. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references. / Abstracts also in Chinese.
313

Total synthesis of neolignans.

Mak, Ching-Pong January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemistry. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.
314

Stable Cyclopropenium-Based Radicals

Strater, Zack Michael January 2019 (has links)
Stable radicals have enjoyed widespread use in a variety of fields including synthetic chemistry, materials chemistry, energy storage, and biochemistry. This thesis outlines our investigations of cyclopropenium-based stable radicals and their application as redox mediators, redox-active ligands, catalysts, and materials for energy storage. The first chapter gives a brief overview of the use of radicals in synthetic chemistry. The principles that govern the stability of radicals is discussed and notable examples are highlighted. The second section of the first chapter reviews the aromatic platforms that have been developed by the Lambert group and how they might be converted into stable radical species. The second chapter details our study of 2,3-diaminocyclpropenones as stable radicals. These electron rich cyclopropenium derivatives undergo facile oxidation to yield a radical cation species. The origin of the stability of this oxygen-centered radical was elucidated by density functional theory calculations and analysis of the crystal structure. Diaminocyclopropenones were also found to be effective neutral L-type ligands in Ce(IV) complexes. EPR and UV-VIS experiments revealed that these complexes exhibited reversible homolytic dissociation of their diaminocyclopropenone ligands. The third chapter describes the use of trisaminocyclopropeniums as catholytes for nonaqueous redox flow batteries. A newly designed trisaminocyclopropenium structure could be accessed in large quantities and showed long lasting stability in its oxidized state. A new composite polyionic material was developed for use as a membrane suitable for organic solvent and high voltages. Cycling in combination with a perylenediimide anolyte yielded a 1.7 V battery that exhibited excellent coulombic efficiency and capacity retention. Using a spiro-bis(phthalimido) anolyte afforded a battery with an open circuit voltage of 2.8 V. The fourth chapter details how our battery studies with trisaminocyclopropenium radical dications led us to discover their photoinduced reactivity. We developed an electrophotocatalytic platform using trisaminocyclopropeniums as a species capable of being activated by both photochemical and electrochemical energy. The excited state oxidation potential of the doubly activated species was found to be +3.33 V, which was capable of effecting oxidative coupling reactions using both arenes and ethers as substrates. Density functional theory calculations and spectroscopic experiments revealed that the photoreactivity was due to a SOMO-inversion event. The trisaminocyclopropenium radical dication could be prepared on scale via direct electrolysis and subsequently used in high throughput screening.
315

Vinylsilanes and allysilanes in electrophilic substitution reactions : stereocontrolled synthesis of insect sex pheromones

Koumaglo, Mensah-Dzraku Kossi January 1985 (has links)
No description available.
316

Synthetic, spectroscopic, and kinetic studies of some -cyclopentadienylmetal complexes.

Fenster, Ariel Elie. January 1972 (has links)
No description available.
317

Phosphodichloridite reagents in the solution and solid phase synthesis of oligoribonucleotides

Pon, Richard T. (Richard Timothy) January 1984 (has links)
No description available.
318

Biscyclopentadienyl complexes of molybdenum (IV) and Tungsten (IV) containing polysulfane ligands

Marmolejo Rivas, Gabriela. January 1986 (has links)
No description available.
319

Synthesis of compounds of natural and unnatural origin by intramolecular alkylations / by Neil John Shirley

Shirley, Neil John January 1987 (has links)
Bibliography: leaves 213-223 / viii, 224 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Organic Chemistry, 1987
320

Chemical, spectroscopic and kinetic studies of staphylonuclear compounds of molybdenum and related elements / Wilhelm von Bronswyk.

Bronswyk, Wilhelm von January 1967 (has links)
"January 1967." / Includes bibliographical references. / v, 238 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1967

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