Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 203 for “"sterically"”.
-
Sterically Crowded Copolymers Based on Functionalized Stilbenes
… focused on the synthesis and characterization of sterically crowded, precisely charged polyelectrolytes based on substituted stilbene comonomers. New sterically crowded polyelectrolytes based on functionalized stilbenes with maleic anhydride or functionalized N-phenylmaleimides were prepared via a …
-
Studies of Sterically Controlled Solvent Induced NMR Chemical Shifts
Recently Homer and Percival have postulated that intermolecular van der Waals dispersion forces can be characterized by three mechanisms. The first arises via the mean square reaction field due to the transient dipole of a particular solute molecule that is considered situated in a cavity …
-
Transvascular transport of sterically stabilized liposomes and particles in transplanted tumors
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1998.
-
Novel N-heterocyclic activations mediated by magnesium reagents having sterically hindered ligands
… of homometallic Mg compounds bearing highly sterically demanding ligands, but going significantly beyond the state-of-the-art, this thesis report focuses on the synthesis of new sodium magnesiates and magnesium reagents supported by bulky N-chelating ligands {Ph2Si(NAr*)2}2- and …
-
The synthesis of sterically demanding ligands and examples of their copper complexes
… in roughly 24 hours, with the more sterically demanding substrates requiring altered conditions. Typical isolated yields are in excess of 70%. Moreover, methyl- and aryl-substituted pyrrolyl anions have been shown to display similar chemistry using 5.0 mol% Pd(OAc)₂. Though they …
-
Synthesis and reactivity of vanadium and niobium complexes containing sterically demanding amido ligands
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1998.
-
Synthesis and application of sterically flexible and water-soluble phosphine ligands in palladium catalysis
… particularly for the Suzuki coupling of sterically hindered substrates. I have also synthesized two new water-soluble phosphine ligands that utilize two sterically hindered, electron-rich alkyl groups (di-tert-butyl or di-1-adamantyl) in conjunction with a flexible benzyl moiety, made …
-
Synthesis and reactivity of early transitional metal complexes supported by sterically demanding amido ligands
Chapter 1: Ligand Synthesis Strategies -- Chapter 2: Early Transition Metal Complexes of Bidentate N[R]ArL, o-Dimethylamino- N-tert-Butylanilide -- Chapter 3: Three-Coordinate Molybdenum(III) Complexes: Synthesis, Properties, and Nitrogen Atom Transfer Thereto -- Chapter 4: The …
-
The kinetics of hydrolysis and the electronic absorption spectra of some sterically hindered basic dyes
A comprehensive series of derivatives of Malachite Green substituted in the phenyl ring with silicon, phosphorus, sulphur, nitrdgen or oxygen containing groups have been synthesised. Their absorption spectra have been measured in 98% acetic acid solution and compared with that of Malachite Green. …
-
Investigations of sterically demanding ligands in molybdenum and tungsten monopyrrolide monoalkoxide catalysts for olefin metathesis
Chapter 2 investigates the mechanism of the temperature-controlled polymerization of 3- methyl-3-phenylcyclopropene (MPCP) by Mo(NAr)(CHCMe 2Ph)(Pyr)(OTPP) (Ar = 2,6- diisopropylphenyl, Pyr = pyrrolide, OTPP = 2,3,5,6-tetraphenylphenoxide). Cissyndiotactic poly(MPCP) is obtained at -78 °C, while …
-
Controlling the reactivity of Mo(III) with di- and tri-atomic molecules via sterically demanding ligands
Chapter 1. Molybdenum Dinitrogen Chemistry: Formation and Reactivity of (Ar[tBu]N)3MoN2- A collection of (Ar[tBu]N)3MoN2- compounds, supported with Na+, K+, Mg2+ and Ca2+ have been prepared through a variety of synthetic routes. In several experiments, N2 was replaced with other small molecules to …
-
Modeling the active sites of non-heme diiron metalloproteins with sterically hindered carboxylates and syn N-Donor ligands
Chapter 1. Different Synthetic Approaches to Modeling the Active Sites of Carboxylate-Bridged Non-Heme Diiron Enzymes Carboxylate-bridged non-heme diiron enzymes activate dioxygen to perform a variety of biological functions. Synthetic model compounds have been prepared to gain insight into the …
-
Vanadium and chromium complexes supported by sterically demanding ligands : studies relevant to the reduction of dinitrogen to ammonia
Chapter 1. Using the [HIPTN3N]3- ligand ([HIPTN3N]3- = [(HIPTNCH2CH2)3N]3-; HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = HexaIsoPropylTerphenyl), green paramagnetic [HIPTN3N]V(THF) (1) can be prepared from VCl3(THF)3. Reduction of 1 with potassium graphite in ethereal solvents yields a highly sensitive red …
-
Use of sterically hindered carboxylate ligands to model structural and functional features of dioxygen-activating centers in non-heme diiron enzymes
… Shifts in Diiron(II) Complexes Supported by Sterically Hindered Carboxylate Ligands General synthetic routes are described for a series of diiron(II) complexes supported by sterically demanding carboxylate ligands 2,6-di(p-tolyl)benzoate (ArTolCO2-) and 2,6-di(4-fluorophenyl)benzoate …
-
Synthesis and reactivity of early transition metal "Frustrated Lewis Pairs"
… of "Frustrated Lewis Pairs" (FLP) wherein sterically demanding Lewis acids and bases do not interact in the expected donor-acceptor fashion, but rather exhibit unique reactivity. To date this concept of FLPs has been limited to main group systems. In this thesis we demonstrate that Lewis …
-
Steric and Electronic Effects Induced by Ancillary Ligand Substitutions on Cyclopentadienyl Osmium Complexes
… [(C5Me5)Os(dmpm)H2+] showed that C5Me5 is more sterically demanding than C 5H5, as evidenced by the 7--8° decrease in the dihedral angle between the P-Os-P and C5 ring planes for the C5H 5 analogue, suggesting that movement of the phosphine toward the less sterically bulky C5 ring may lead …
-
Palladium(II)-Catalysed sp 3 C–H Functionalisation of Hindered Amines and its Application in Synthesis of Astemizole Analogues
… hindered secondary amines that facilitates a sterically promoted palladium-catalysed C–H activation. A range of functional groups are shown to be compatible with this catalytic process, and with exclusive regioselectivity for the terminal ethyl sp 3 C–H in most cases. This method allows an …
-
Compounds of Pentacoordinate (10-Boron-5) and Hexacoordinate (12-Boron-6) Hypervalent Boron
… involving direct ortho lithiation with the sterically hindered base, lithium 2,2,6,6-tetramethylpiperidide, in the presence of electrophiles that are compatible with the base, e.g., trimethylsilyl chloride and hexafluoroacetone.
Page 1 of 11