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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.
1

Divalent iron, cobalt, nickel and palladium complexes of 1H-pyrazol-1-yl-imine and 1H-pyrazol-1-yl-ethanol ligands: coordination chemistry and evaluation as ethylene oligomerization catalysts

16 May 2011 (has links)
M.Sc. / This dissertation deals with the syntheses of tridentate (O^N^N) coordination ligands [{2,4-di-tert-butyl-6-[(2-(3,5-RR-pyrazol-1-yl-ethylimino)-methyl] phenol}, R = H (L1), Me(L2), Ph(L3), t-Bu(L4)], which was reacted initially with MX2 (M = Fe, Co, Ni; X = Cl, Br). The ligands L1-L4 were also modified by functionalizing the phenol group in this ligand group to an ethoxy in L5 and L6 (L5 = [(3,5-di-tert-butyl-2-ethoxy-benzylidene)-[2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-amine, L6 = [(3,5-di-tert-butyl-2-ethoxy-benzylidene)-[2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl]-amine)], or into a phenoxy in L7 (L7 = (3,5-di-tert-butyl-2-phenoxy-benzylidene-(2-pyrazol-1-yl-ethyl)-amine)). Another ligand L8 (L8 = [4-(4-tert-butyl-benzylidene)-[2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-amine], which was devoid of the phenoxy group was also synthesized. These modified ligands were also reacted with MX2 or PdCl(COD)Me to form bidentate (N^N) chelating complexes. Further modification of the ligand L1-L4, to replace the phenoxy pyrazolylimine unit with a source of oxygen donor other than a phenoxy led to the use of already known ligands L9, L10 (L9 = 2-(3,5-dimethyl-pyrazol-1-yl)-ethanol, L10 = 2-(3,5-di-tert-butyl-pyrazol-1yl)-ethanol and L11, where in L11, the alcohol moiety is replaced by an electron withdrawing chloro group, L11 = 1-(2-chloroethyl)-3,5-di-methyl-pyrazole). These ligands were also reacted with MX2 (M = Fe, Co, Ni, Pd; X = Cl, Br) to form complexes. The synthesized complexes were characterized by a combination of IR and NMR spectroscopy, mass spectrometry, microanalysis and in selected cases single crystal X-ray crystallography.
2

Cyklizační reakce 1,5-enynů katalyzované komplexy zlata / Gold-Catalyzed Cyclizations of 1,5-Enynes

Matouš, Petr January 2020 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department Department of Organic and Bioorganic Chemistry Candidate Mgr. Petr Matouš Supervisor prof. RNDr. Milan Pour, Ph.D. Titel of Doctoral Thesis Gold-Catalyzed Cyclizations of 1,5-Enynes This Ph.D. thesis deals with the development of gold(I)-catalyzed cyclizations of propargylamino acrylates (3-aza-1,5-enynes) in the presence of an external nucleophile. A library of tetrahydropyridines with an unusual hemiaminal ether functional group was thus prepared via the cyclization of a series of substituted enynes. The influence of the protective group as well as the substitution on the chemoselectivity of the reaction was demonstrated. The tetrahydropyridines were further utilized as precursors for the preparation of pharmaceutically important nitrogen heterocycles. The reduction of selected compounds furnished substituted piperidines, while Diels-Alder cycloaddition of alkenylated tetrahydropyridines gave rise to isoquinoline derivatives. Additional ortho-fused heterocycles (furopyridine, pyrrolopyridine and chromenopyridine) were prepared by the intramolecular version of the cyclizations of enynes with pending internal nucleophiles.
3

Synthesis and characterisation of electronically active species

Mahenthirarajah, Thushitha January 2009 (has links)
An exploration of some early transition metal (oxy) fluoride systems using solvothermal techniques has been carried out. 30 novel materials have been synthesised, which fall into three classes based on different metal centres; vanadium (21), molybdenum (5) and niobium (4). Some of these also contain secondary metal centres, namely copper (22) and zinc (1). Simultaneously, the relationship between the SHG values and the crystal structures of the hilgardites family members Pb₂B₅O₉Cl, Pb₂B₅O₉Br, Sr₂B₅O₉Cl and Ba₂B₅O₉Cl was investigated. In particular, the Pb–containing members of the hilgardite family of borate halides exhibit an abnormally large non–linear optical response, which was analysed based on neutron powder diffraction. Using solvothermal synthesis in HF–containing media, 21 novel vanadium oxyfluorides containing interesting structural features, were synthesised at 160˚C using a range of organo-amine compounds as a ligand, template, linker or structure directing agent. The architectures of the crystal structures may be categorised into; four clusters including monomeric vanadium units, five clusters including vanadium dimers, eight 1–D chains, two 2–D layers and two 3–D networks. ‘Composition–space’ diagrams with three components were used to study the effect of stoichiometry changes of reactants and to map out the crystallisation fields. The combination of early (Nb⁵⁺, Mo⁶⁺) and late (Cu²⁺) transition metals with different organo-amines produced nine novel compounds incorporating monomers, chains and 2– D interpenetrated networks. The chains and layers were synthesised from a systematic series of reactions at 160˚C and can be subdivided into four pairs, the topologies of which are essentially unique to each ligand, containing in each case a Cu–based cationic species, but alternately either [MoO₂F₄]²⁻ or [NbOF₅]²⁻, in an isomorphous manner, as the anionic moiety. The overall structures of these materials reflect the influence of the organo–amine ligands. The materials have been studied for their magnetic properties and characterised by thermogravimetric analysis, Rietveld refinement and elemental analysis where relevant.

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