Global ETD Search

1	On Thallium (III) and binuclear platinum-thallium complexes with N-donor ligands in solution and in solid Ma, Guibin January 2001 (has links) This thesis describes the synthesis, structure, equilibriaand other properties of novel thallium(III) monomeric andplatinum-bonded complexes with nitrogen donor ligandsethylenediamine, diethylenetriamine, triethylenetetramine,porphyrin, 2,2'-bipyridine and 1,10-phenanthroline in solutionand in solid. The existence of three complexes withthe general formula[Tl(en)n]3+(n = 1-3) and their overall stability constantshave been established in pyridine. All three complexes wereidentified by their205Tl and1H NMR chemical shifts and205Tl-1H coupling constants. The formation process of thecomplexes was followed by1H NMR spectroscopy. The crystal structure of[Tl(en)3](ClO4)3was determined; the thallium(III) ion isN-coordinated in a distorted octahedral geometry. Two [Tl(dien)n]3+(n = 1-2) complexes were proved to exist insolution and the structure of the bis-complex [Tl(dien)2]2+inu-facialisomers was determined in solid. In addition,crystal structures of [Tl(en)2CN](ClO4)2with cyanide bridging between two Tl(en)2units forming an infinite chain structure and of[Tl(tren)2(CN)2](ClO4) with a distorted pseudo-octahedral coordinationaround thallium were determined. Thallium(III) complexes with2,2'-bipyridine and 1,10-phenanthroline have been studied inDMSO using205Tl,13C and1H NMR spectroscopy. In addition, aseven-coordinated thallium was found in the crystal structureof [Tl(bipy)3(dmso)](ClO4)3, and six-coordinated thallium in pseudo-octahedralgeometry in [Tl(phen)2Cl2](ClO4). The solvated complex [Tl(dmso)6]3+has been prepared using concentrated aqueoussolution of Tl(ClO4)3by a solvent replacement reaction in DMSO, and thewater-free solid compound [Tl(dmso)6](ClO4)3was crystallized from DMSO. The structure of thecomplex [Tl(dmso)6]3+is a regular octahedron with the Tl-O bonddistance 2.224(3) Å. It represents an easy and secure wayto introduce water-free Tl(III) into organic phase withoutreduction. Through several reactions, novel heteronuclear Pt-Tlcomplexes with the composition [(NC)5Pt-Tl(tpp)]2-, [(NC)5Pt-Tl(thpp)]2-, [(NC)5Pt-Tl(bipy)n](n = 1-2), [(NC)5Pt-Tl(en)n-1](n = 1-3) and [(NC)5Pt-Tl(phen)n](n = 1-2), have been synthesized in solution.Multinuclear NMR (195Pt,205Tl,13C and1H), Raman spectroscopy and X-ray diffraction dataare fully compatible with formation of unsupported Pt-Tl bondedcomplexes both in solution and in solid. The huge1J(195Pt-205Tl) spin-spin coupling constants (48-66 kHz) wereobserved by both195Pt and205Tl NMR spectroscopy in solution and they providea strong evidence of formation of the Pt-Tl bond in solution.In all six determined crystal structures of the Pt-Tl compoundsa very short Pt-Tl bond is found with distances2.6117(5)-2.6375(5) Å. The calculated values of Pt-Tlforce constants (1.38-1.91 N/cm) are characteristic for asingle metal-metal bond. In the Pt-Tl compounds, the oxidation state of the metalions is intermediate between the stable states PtII/PtIVand TlIII/TlI, respectively, and this is reflected by their195Pt and205Tl chemical shifts. It turns out that N-donorligands can really stabilize the Pt-Tl bond both in solutionand in solid. The character of the metal-metal bond anditstheoretical basis are discussed. <b>Keywords:</b>Thallium, Platinum, Cyanide, N-donor ligand,Metal-metal bond, Multinuclear NMR, Raman spectroscopy, X-raydiffraction, Equilibrium, Spin-spin coupling. thallium platinum cyanide n-donor ligand metal-metal bond multinuclear NMR raman spectroscopy
2	The Complex Of 2-aminothiophenol Ligand With Platinum: A Novel Platinum Blues Containing Sulfur Donor Ligand Erilhan, Ismail 01 June 2007 (has links) (PDF) The reaction of potassiumtetrachloroplatinate with 2-aminothiophenol, yielded a dark blue solid product. This work is about the characterization of this dark blue solid and the investigation of its binding interaction to DNA and enzyme activity. The blue solid product or the &ldquo / blue complex&rdquo / (as we called it in this work) is soluble in acetone, acetonitrile and DMSO yielding a blue solution. It is stable in solution and has a very strong absorption band at 724 nm. The product is paramagnetic and displays one kind of platinum in XPS (platinum binding energies were obtained at 71.1 and 74.6 eV, respectively). The elemental (C, H, N, S, Pt) analysis indicated that the platinum to ligand (2- aminothiophenolate) mole ratio is 1:2. The interpretation of the data collected from elemental analysis and ESR, XPS, NMR, CV measurements leads to conclude that the blue complex prepared in this work is a new platinum blues. This is the first example of platinum blues, in which the bridging ligand is a nitrogen and sulfur donor one. The proposed structure can be visualized as a dimer of binuclear head-tohead isomer of the green product, with C2h symmetry. The band at 724 nm is assigned to an allowed electronic transition from a metal-5dz orbitals based MO to metal-6pz orbitals based MO in tetranuclear core. In order to determine the binding mode of the blue complex to ct-DNA, electronic absorption spectroscopy is employed and hyperchromism about 17.5 percent is observed, which indicates a weak binding of the blue complex to DNA, such as electrostatic interaction of metal ions or H-bonding through the hydroxyl group of the complex. Voltammetric titration carried out in solution suggested the preferential stabilization of Pt(III) to Pt(II) on binding to DNA. The blue complex inhibits the GSTs activity between 45-200 micromolar, in sheep liver GST enzyme. The GST enzymes causes drug resistance, therefore inhibition of this enzyme suggests that this complex can be used in combined chemotherapy. QD Inorganic Chemistry 146-197
3	On Thallium (III) and binuclear platinum-thallium complexes with N-donor ligands in solution and in solid Ma, Guibin January 2001 (has links) <p>This thesis describes the synthesis, structure, equilibriaand other properties of novel thallium(III) monomeric andplatinum-bonded complexes with nitrogen donor ligandsethylenediamine, diethylenetriamine, triethylenetetramine,porphyrin, 2,2'-bipyridine and 1,10-phenanthroline in solutionand in solid.</p><p>The existence of three complexes withthe general formula[Tl(en)<sub>n</sub>]<sup>3+</sup>(n = 1-3) and their overall stability constantshave been established in pyridine. All three complexes wereidentified by their<sup>205</sup>Tl and<sup>1</sup>H NMR chemical shifts and<sup>205</sup>Tl-<sup>1</sup>H coupling constants. The formation process of thecomplexes was followed by<sup>1</sup>H NMR spectroscopy. The crystal structure of[Tl(en)<sub>3</sub>](ClO<sub>4</sub>)<sub>3</sub>was determined; the thallium(III) ion isN-coordinated in a distorted octahedral geometry. Two [Tl(dien)<sub>n</sub>]<sup>3+</sup>(n = 1-2) complexes were proved to exist insolution and the structure of the bis-complex [Tl(dien)<sub>2</sub>]<sup>2+</sup>in<i>u-facial</i>isomers was determined in solid. In addition,crystal structures of [Tl(en)<sub>2</sub>CN](ClO<sub>4</sub>)<sub>2</sub>with cyanide bridging between two Tl(en)<sub>2</sub>units forming an infinite chain structure and of[Tl(tren)<sub>2</sub>(CN)<sub>2</sub>](ClO<sub>4</sub>) with a distorted pseudo-octahedral coordinationaround thallium were determined. Thallium(III) complexes with2,2'-bipyridine and 1,10-phenanthroline have been studied inDMSO using<sup>205</sup>Tl,<sup>13</sup>C and<sup>1</sup>H NMR spectroscopy. In addition, aseven-coordinated thallium was found in the crystal structureof [Tl(bipy)<sub>3</sub>(dmso)](ClO<sub>4</sub>)<sub>3</sub>, and six-coordinated thallium in pseudo-octahedralgeometry in [Tl(phen)<sub>2</sub>Cl<sub>2</sub>](ClO<sub>4</sub>).</p><p>The solvated complex [Tl(dmso)<sub>6</sub>]<sup>3+</sup>has been prepared using concentrated aqueoussolution of Tl(ClO<sub>4</sub>)<sub>3</sub>by a solvent replacement reaction in DMSO, and thewater-free solid compound [Tl(dmso)<sub>6</sub>](ClO<sub>4</sub>)<sub>3</sub>was crystallized from DMSO. The structure of thecomplex [Tl(dmso)<sub>6</sub>]<sup>3+</sup>is a regular octahedron with the Tl-O bonddistance 2.224(3) Å. It represents an easy and secure wayto introduce water-free Tl(III) into organic phase withoutreduction.</p><p>Through several reactions, novel heteronuclear Pt-Tlcomplexes with the composition [(NC)<sub>5</sub>Pt-Tl(tpp)]<sup>2-</sup>, [(NC)<sub>5</sub>Pt-Tl(thpp)]<sup>2-</sup>, [(NC)<sub>5</sub>Pt-Tl(bipy)<sub>n</sub>](n = 1-2), [(NC)<sub>5</sub>Pt-Tl(en)<sub>n-1</sub>](n = 1-3) and [(NC)<sub>5</sub>Pt-Tl(phen)<sub>n</sub>](n = 1-2), have been synthesized in solution.Multinuclear NMR (<sup>195</sup>Pt,<sup>205</sup>Tl,<sup>13</sup>C and<sup>1</sup>H), Raman spectroscopy and X-ray diffraction dataare fully compatible with formation of unsupported Pt-Tl bondedcomplexes both in solution and in solid. The huge<sup>1</sup>J(<sup>195</sup>Pt-<sup>205</sup>Tl) spin-spin coupling constants (48-66 kHz) wereobserved by both<sup>195</sup>Pt and<sup>205</sup>Tl NMR spectroscopy in solution and they providea strong evidence of formation of the Pt-Tl bond in solution.In all six determined crystal structures of the Pt-Tl compoundsa very short Pt-Tl bond is found with distances2.6117(5)-2.6375(5) Å. The calculated values of Pt-Tlforce constants (1.38-1.91 N/cm) are characteristic for asingle metal-metal bond.</p><p>In the Pt-Tl compounds, the oxidation state of the metalions is intermediate between the stable states Pt<sup>II</sup>/Pt<sup>IV</sup>and Tl<sup>III</sup>/Tl<sup>I</sup>, respectively, and this is reflected by their<sup>195</sup>Pt and<sup>205</sup>Tl chemical shifts. It turns out that N-donorligands can really stabilize the Pt-Tl bond both in solutionand in solid. The character of the metal-metal bond anditstheoretical basis are discussed.</p><p><b>Keywords:</b>Thallium, Platinum, Cyanide, N-donor ligand,Metal-metal bond, Multinuclear NMR, Raman spectroscopy, X-raydiffraction, Equilibrium, Spin-spin coupling.</p> thallium platinum cyanide n-donor ligand metal-metal bond multinuclear NMR raman spectroscopy
4	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)
5	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)

1

Page generated in 0.037 seconds