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1	Adsorption of 1H, 1H, 2H, 2H-perfluorodecanethiol monolayer on Cu(111): phase transformation, self-assembly and thermal stability Chou, Shang-Wei 30 July 2003 (has links) Inspired by Poirier¡¦s mechanism of self-assembled monolayers (SAMs) formation, we realized that observation of the change of molecular orientation relative to the surface using a suitable spectroscopic method might be able to reveal the self ¡V assemblied processes. We mimicked the SAMs formation under UHV conditions, the Reflection Absorption Infrared Spectroscopy (RAIRS) and Temperature-Programmed Desorption / Reaction Spectrometry (TPD/R) were utilized to understand the adsorption, self-assembling and thermal stability after vapor desorption of 1H, 1H, 2H, 2H-perfluorodecanethiol on Cu(111). At 100K, the adsorption of 1H, 1H, 2H, 2H-perfluorodecanethiol was entirely molecular. As the surface was annealed above 220K, the cleavage of the S ¡V H bonds occurred to afford chemisorbed thiolates. By comparisons of spectra to the SAMs / Au(111) and the bulk compound, forming of an orderly and densely packed monolayer on Cu(111) was inferred. Focusing on room temperature deposition experiments, We found that the increase in ratios of I£h(CF2 ¡ü chain) (bands in 1300cm-1 ~ 1400 cm-1) to I£h(CF2 ¡æ chain) (bands in 1100cm-1 ~ 1300 cm-1) as a function of exposure implicates a transition from that the lying ¡V down geometry to the more upright orientation relative to the surface as we anticipated, the phase transformation concomitant with the SAMs formation could be identified by RAIRS. By TPD/R measurements, the molecular desorption occurred at 220K and 290K, corresponding to the condensed multilayer and a physisorbed layer on top of the chemisorbed monolayer, respectively. Furthermore, the monolayer would undergo the S ¡V C bond dissociation to sender surface ¡V bound semifluorinated alkyl groups and sulfur atoms. The semifluorinated decene and decane were evolved above 360K as results of £] ¡V hydride elimination and hydrogen addition. RAIRS Fluorocarbonchain £]-hydrogen elimination Addition of hydrogen UHV Thermal stability Self-assembly monolayers phase transformation
2	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)
3	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 (has links) Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)

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