Bis(pyrazolyl) chromium(III), nickel(II) and palladium(II) complexes as ethylene oligomerization and polymerization catalysts
- Authors: Miti, Nangamso Alicia
- Date: 2010-03-10T06:22:17Z
- Subjects: Chromium compounds , Nickel compounds , Nickel catalysts , Palladium compounds , Palladium catalysts , Polymerization , Ethylene , Chromium catalysts
- Type: Thesis
- Identifier: uj:6656 , http://hdl.handle.net/10210/3062
- Description: M.Sc. , In search of developing new pyrazolyl complexes that can be used for ethylene transformation reactions, bis(pyrazolyl)alky carbonyl and amine complexes were prepared. The reaction between 3,5-dimethylpyrazole with alkyl-carbonyl chloride linkers in the presence of triethylamine as a base produced the ligands, 1,3-bis(3,5- dimethylpyrazol-1-yl)-propan-1-one (L1), 1,2-bis(3,5-dimethylpyrazol-1-yl)-ethane- 1,2-dione (L2), 1,4-bis(3,5-dimethylpyrazol-1-yl)-butane-1,4-dione (L3) and 1,6- bis(3,5-dimethylpyrazol-1-yl)-hexane-1,6-dione (L4) as white to brown crystalline solids in good yields. Ligand L5 was prepared by using bis(2-chloroethyl)-amine hydrochloride and 3,5- dimethylpyrazolevia via a phase-transfer reaction, while L6 was obtained using the bis(2-chloroethyl)-amine hydrochloride and 3,5-diphenypyrazole in the presence of triethylamine as a base. They were isolated in moderate yields, while their ditertiarypyrazole derivative was not obtained at all. All the ligands were characterized by a combination of 1H and 13C{1H}-NMR spectroscopy, infrared spectroscopy, elemental analysis and mass spectrometry. Ligands L1 and L4 were further confirmed by X-ray crystallography. Ligands L1 and L6 were subsequently used to prepare their corresponding Pd, Ni and Cr complexes. L1 was reacted with [PdCl2(NCMe)2] to form a bidentate complex 1,3- bis-(3,5-dimethylpyrazol-1-yl)-propan-1-one palladium dichloride (1a) when the reaction was heated at 80 oC, while a tridentate complex 1,3-bis(3,5-dimethylpyrazol- 1-yl)-propan-1-one palladium chloride (1b) was obtained when the reaction was refluxed. 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one nickel(II) bromide (2) was obtained when NiBr2 was reacted with L1 at room temperature while the reaction between L1 and [CrCl3(THF)3] gave 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one chromium(III) chloride (3). Ligand L6 was reacted with the same metal salts to give bis[2-(3,5-dimethylpyrazol- 1-yl)-ethyl] amine palladium(II) chloride (4), bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine nickel(II) chloride (5) and bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine chromium(III) chloride (6). All the complexes were characterized by the already mentioned characterization techniques and X-ray analysis was performed for 1b and 4. Ethylene transformation reactions were performed with complexes 1a, 2, 3, 5 and 6, and complexes 1a and 4 were not used because of their geometrical structures, which prevented them to be active for such reactions. Using MMAO and EtAlCl2 as cocatalysts complexes 1a and 3 showed no activity, however complexes 2 and 6 were active. Complex 2 was used with MMAO and showed no activity, while with EtAlCl2 oligomers were produced. Gas-chromatography analysis of the products showed that C6-C14+ oligomers were obtained. Temperature variation reactions performed under standard conditions of 20 bar ethylene pressure and 200 equivalents of EtAlCl2 in one hour showed that certain oligomers were not favoured under certain temperatures. Ethylene reactions with complex 6 and EtAlCl2 did not form any product but with MMAO polymer material was obtained. Analysis of the polymer by differential scanning calometry proved that the product was high density polyethylene. Studies of temperature, co-catalyst and pressure variations were performed. As expected for temperature studies the catalyst decomposed at high temperatures (above 40 oC), while for co-catalyst studies 3000 equivalents of MMAO gave the lowest TON. Pressure variations studies showed that an increase in ethylene pressure also increased the TON, but above 30 bar the activity became stable.
- Full Text:
- Authors: Miti, Nangamso Alicia
- Date: 2010-03-10T06:22:17Z
- Subjects: Chromium compounds , Nickel compounds , Nickel catalysts , Palladium compounds , Palladium catalysts , Polymerization , Ethylene , Chromium catalysts
- Type: Thesis
- Identifier: uj:6656 , http://hdl.handle.net/10210/3062
- Description: M.Sc. , In search of developing new pyrazolyl complexes that can be used for ethylene transformation reactions, bis(pyrazolyl)alky carbonyl and amine complexes were prepared. The reaction between 3,5-dimethylpyrazole with alkyl-carbonyl chloride linkers in the presence of triethylamine as a base produced the ligands, 1,3-bis(3,5- dimethylpyrazol-1-yl)-propan-1-one (L1), 1,2-bis(3,5-dimethylpyrazol-1-yl)-ethane- 1,2-dione (L2), 1,4-bis(3,5-dimethylpyrazol-1-yl)-butane-1,4-dione (L3) and 1,6- bis(3,5-dimethylpyrazol-1-yl)-hexane-1,6-dione (L4) as white to brown crystalline solids in good yields. Ligand L5 was prepared by using bis(2-chloroethyl)-amine hydrochloride and 3,5- dimethylpyrazolevia via a phase-transfer reaction, while L6 was obtained using the bis(2-chloroethyl)-amine hydrochloride and 3,5-diphenypyrazole in the presence of triethylamine as a base. They were isolated in moderate yields, while their ditertiarypyrazole derivative was not obtained at all. All the ligands were characterized by a combination of 1H and 13C{1H}-NMR spectroscopy, infrared spectroscopy, elemental analysis and mass spectrometry. Ligands L1 and L4 were further confirmed by X-ray crystallography. Ligands L1 and L6 were subsequently used to prepare their corresponding Pd, Ni and Cr complexes. L1 was reacted with [PdCl2(NCMe)2] to form a bidentate complex 1,3- bis-(3,5-dimethylpyrazol-1-yl)-propan-1-one palladium dichloride (1a) when the reaction was heated at 80 oC, while a tridentate complex 1,3-bis(3,5-dimethylpyrazol- 1-yl)-propan-1-one palladium chloride (1b) was obtained when the reaction was refluxed. 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one nickel(II) bromide (2) was obtained when NiBr2 was reacted with L1 at room temperature while the reaction between L1 and [CrCl3(THF)3] gave 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one chromium(III) chloride (3). Ligand L6 was reacted with the same metal salts to give bis[2-(3,5-dimethylpyrazol- 1-yl)-ethyl] amine palladium(II) chloride (4), bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine nickel(II) chloride (5) and bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine chromium(III) chloride (6). All the complexes were characterized by the already mentioned characterization techniques and X-ray analysis was performed for 1b and 4. Ethylene transformation reactions were performed with complexes 1a, 2, 3, 5 and 6, and complexes 1a and 4 were not used because of their geometrical structures, which prevented them to be active for such reactions. Using MMAO and EtAlCl2 as cocatalysts complexes 1a and 3 showed no activity, however complexes 2 and 6 were active. Complex 2 was used with MMAO and showed no activity, while with EtAlCl2 oligomers were produced. Gas-chromatography analysis of the products showed that C6-C14+ oligomers were obtained. Temperature variation reactions performed under standard conditions of 20 bar ethylene pressure and 200 equivalents of EtAlCl2 in one hour showed that certain oligomers were not favoured under certain temperatures. Ethylene reactions with complex 6 and EtAlCl2 did not form any product but with MMAO polymer material was obtained. Analysis of the polymer by differential scanning calometry proved that the product was high density polyethylene. Studies of temperature, co-catalyst and pressure variations were performed. As expected for temperature studies the catalyst decomposed at high temperatures (above 40 oC), while for co-catalyst studies 3000 equivalents of MMAO gave the lowest TON. Pressure variations studies showed that an increase in ethylene pressure also increased the TON, but above 30 bar the activity became stable.
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trans-Dichloridobis[diphenyl(4-vinylphenyl) phosphane-kP]palladium(II)
- Authors: Meijboom, Reinout
- Date: 2011
- Subjects: X-ray crystallography , Crystallography , Palladium compounds
- Type: Article
- Identifier: uj:5871 , ISSN 1600-5368 , http://hdl.handle.net/10210/7969
- Description: Please refer to full text to view abstract
- Full Text:
- Authors: Meijboom, Reinout
- Date: 2011
- Subjects: X-ray crystallography , Crystallography , Palladium compounds
- Type: Article
- Identifier: uj:5871 , ISSN 1600-5368 , http://hdl.handle.net/10210/7969
- Description: Please refer to full text to view abstract
- Full Text:
Synthesis of poly (pyrazolylmethyl) benzene palladium complexes as catalysts for Heck and Suzuki coupling reactions
- Authors: Motsoane, Nthabiseng Marcia
- Date: 2008-06-10T05:47:05Z
- Subjects: Palladium compounds , Palladium compounds synthesis , Palladium catalysts
- Type: Thesis
- Identifier: uj:9532 , http://hdl.handle.net/10210/595
- Description: This thesis covers an investigation of the use of pyrazolyl palladium complexes as Heck and Suzuki coupling catalysts. It is organised into four chapters. Chapter 1 is a review of the relevant literature and therefore does not cover any new work. Chapters 2 and 3 describe the synthesis and characterization of palladium complexes and testing as Heck and Suzuki coupling catalysts respectively. Chapter 4 is a summary of conclusions and future work. The subsequent section provides the main findings in chapters 2, 3 and 4. Chapter 2 is on the synthesis and characterization of palladium complexes that were used to catalyse the Heck and the Suzuki coupling reactions. The poly(pyrazol-1-ylmethyl)benzene ligands were prepared from reactions in which bis(bromomethyl)benzene with bromo substituents in different positions were reacted with either 3,5-dimethylpyrazole or 3,5-ditertiarybutylpyrazole. The products formed from these reactions were: {(3,5-Me2pzCH2)4-1,2,4,5-C6H4} (L1), {(3,5-Me2pzCH2)2}2-1,4-C6H4 (L2), {(3,5-tBu2pzCH2)2-1,4-C6H4} (L3), {(3,5-Me2pzCH2)2}2-1,3-C6H4 (L4), and {(3,5-Me2pzCH2)2}2-1,2-C6H4 (L4). Compounds L1-L5 were subsequently used to prepare their corresponding palladium complexes C1-C8, by reacting the poly(pyrazol-1-ylmethyl)benzene ligands L1-L5 with [PdCl2(NCMe)2] or [PdClMe(COD)] to form the tetranuclear palladium complex [{Pd2Cl(3,5-Me2pzCH2)4-1,2,4,5-C6H4}2] (C1), or dinuclear palladium complexes [{Pd2(μ-Cl)2X2(3,5-Me2pzCH2)2-1,4-C6H4}] (X = Cl (C2), Me (C6)), [{Pd2(μ-Cl)2Cl2(3,5-tBu2pzCH2)2-1,4-C6H4}] (C3), [{Pd2ClX(3,5-Me2pzCH2)2-1,3-C6H4}2] (X = Cl (C4), Me (C8), [{Pd2ClX(3,5-Me2pzCH2)2-1,2-C6H4}2] {X = Cl (C5), Me (C7)}, All the compounds were characterized by multinuclear NMR and elemental analysis. The structures of C1, C5 and C7 were confirmed by single crystal X-ray structural analysis. Chapters 3 and 4 describe the use of new palladium complexes prepared in this project as catalysts in Heck and Suzuki cross coupling reactions. The complexes efficiently catalysed the Heck coupling reactions which involved the coupling of iodobenzene and butylacrylate to produce trans-butyl cinnamate at 80 oC, with over 80 % conversion found within 6 h, and over 90 % within 24 h. The Suzuki coupling reactions between iodobenzene and phenylboronic acid were also performed at 80 oC. The Suzuki coupling reactions were not as efficient as the Heck coupling reactions and conversions of more than 70 % could only be reached after 24 h. Complex C6 gave the highest conversions in both the Heck and the Suzuki coupling reactions, with Heck coupling conversions of 100 % within 6 h and Suzuki coupling conversion of 73 % within 24. The major significant finding in using these palladium complexes in the two coupling reactions is that they perform both reactions at a much lower temperature (80 oC) compared to the normal temperatures of 120-160 oC used in such reaction. , Professor James Darkwa
- Full Text:
- Authors: Motsoane, Nthabiseng Marcia
- Date: 2008-06-10T05:47:05Z
- Subjects: Palladium compounds , Palladium compounds synthesis , Palladium catalysts
- Type: Thesis
- Identifier: uj:9532 , http://hdl.handle.net/10210/595
- Description: This thesis covers an investigation of the use of pyrazolyl palladium complexes as Heck and Suzuki coupling catalysts. It is organised into four chapters. Chapter 1 is a review of the relevant literature and therefore does not cover any new work. Chapters 2 and 3 describe the synthesis and characterization of palladium complexes and testing as Heck and Suzuki coupling catalysts respectively. Chapter 4 is a summary of conclusions and future work. The subsequent section provides the main findings in chapters 2, 3 and 4. Chapter 2 is on the synthesis and characterization of palladium complexes that were used to catalyse the Heck and the Suzuki coupling reactions. The poly(pyrazol-1-ylmethyl)benzene ligands were prepared from reactions in which bis(bromomethyl)benzene with bromo substituents in different positions were reacted with either 3,5-dimethylpyrazole or 3,5-ditertiarybutylpyrazole. The products formed from these reactions were: {(3,5-Me2pzCH2)4-1,2,4,5-C6H4} (L1), {(3,5-Me2pzCH2)2}2-1,4-C6H4 (L2), {(3,5-tBu2pzCH2)2-1,4-C6H4} (L3), {(3,5-Me2pzCH2)2}2-1,3-C6H4 (L4), and {(3,5-Me2pzCH2)2}2-1,2-C6H4 (L4). Compounds L1-L5 were subsequently used to prepare their corresponding palladium complexes C1-C8, by reacting the poly(pyrazol-1-ylmethyl)benzene ligands L1-L5 with [PdCl2(NCMe)2] or [PdClMe(COD)] to form the tetranuclear palladium complex [{Pd2Cl(3,5-Me2pzCH2)4-1,2,4,5-C6H4}2] (C1), or dinuclear palladium complexes [{Pd2(μ-Cl)2X2(3,5-Me2pzCH2)2-1,4-C6H4}] (X = Cl (C2), Me (C6)), [{Pd2(μ-Cl)2Cl2(3,5-tBu2pzCH2)2-1,4-C6H4}] (C3), [{Pd2ClX(3,5-Me2pzCH2)2-1,3-C6H4}2] (X = Cl (C4), Me (C8), [{Pd2ClX(3,5-Me2pzCH2)2-1,2-C6H4}2] {X = Cl (C5), Me (C7)}, All the compounds were characterized by multinuclear NMR and elemental analysis. The structures of C1, C5 and C7 were confirmed by single crystal X-ray structural analysis. Chapters 3 and 4 describe the use of new palladium complexes prepared in this project as catalysts in Heck and Suzuki cross coupling reactions. The complexes efficiently catalysed the Heck coupling reactions which involved the coupling of iodobenzene and butylacrylate to produce trans-butyl cinnamate at 80 oC, with over 80 % conversion found within 6 h, and over 90 % within 24 h. The Suzuki coupling reactions between iodobenzene and phenylboronic acid were also performed at 80 oC. The Suzuki coupling reactions were not as efficient as the Heck coupling reactions and conversions of more than 70 % could only be reached after 24 h. Complex C6 gave the highest conversions in both the Heck and the Suzuki coupling reactions, with Heck coupling conversions of 100 % within 6 h and Suzuki coupling conversion of 73 % within 24. The major significant finding in using these palladium complexes in the two coupling reactions is that they perform both reactions at a much lower temperature (80 oC) compared to the normal temperatures of 120-160 oC used in such reaction. , Professor James Darkwa
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Tetra-µ-acetato-κ⁸O:O'-bis[(3,5-dimethyl-1H-pyrazole-κN²)copper(II)]
- Van Wyk, Juanita, Omondi, Bernard, Darkwa, James
- Authors: Van Wyk, Juanita , Omondi, Bernard , Darkwa, James
- Date: 2011
- Subjects: X-ray crystallography , Crystallography , Pyrazolyl ligands , Palladium compounds
- Type: Article
- Identifier: uj:5908 , ISSN 1600-5368 , http://hdl.handle.net/10210/8067
- Description: Pyrazolyl ligands containing a carbonyl linker has been utilized to prepare a number of coordination compounds with palladium salts (Guzei et al., 2003; Mohlala et al., 2005, Ojwach et al., 2005). In these compounds the pyrazolyl carbonyl moiety appear to be robust enough to avoid hydrolysis. However in a few instances the presence of metal ions like Cu(II) (Deka et al., 2006) and Pd(II) (Nelana et al., 2008) appear to catalyze the hydrolysis of the benzoyl fragments. We have observed similar hydrolysis when reacting copper(II) acetate with (3,5-dimethyl-pyrazol-1-yl)-o-benzoyl-methane. The title compound formed from this reaction is the subject of this report. The half "solvent" molecule excluded from the structure had a total number of 30.7 electrons which is approximately half the total number of electrons that acetophenone has. Compound (I) crystallizes with two half molecules in the assymetric unit. The compound is dinuclear with each of the Cu atoms coordinated to four O atoms and a N atom from the pyrazole ligand. The O atoms are from acetate ions, all in the equatorial positions of a slightly distorted octahedral geometry around the Cu atoms. The N atom is bound trans to the Cu—Cu vector completing a the distorted octahedral geometry as axial ligands. The crystal structure of (I) is composed of two N—H···O hydrogen bonded chains (Table 1) that extend in the crystallographic b axis (Fig. 2).
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- Authors: Van Wyk, Juanita , Omondi, Bernard , Darkwa, James
- Date: 2011
- Subjects: X-ray crystallography , Crystallography , Pyrazolyl ligands , Palladium compounds
- Type: Article
- Identifier: uj:5908 , ISSN 1600-5368 , http://hdl.handle.net/10210/8067
- Description: Pyrazolyl ligands containing a carbonyl linker has been utilized to prepare a number of coordination compounds with palladium salts (Guzei et al., 2003; Mohlala et al., 2005, Ojwach et al., 2005). In these compounds the pyrazolyl carbonyl moiety appear to be robust enough to avoid hydrolysis. However in a few instances the presence of metal ions like Cu(II) (Deka et al., 2006) and Pd(II) (Nelana et al., 2008) appear to catalyze the hydrolysis of the benzoyl fragments. We have observed similar hydrolysis when reacting copper(II) acetate with (3,5-dimethyl-pyrazol-1-yl)-o-benzoyl-methane. The title compound formed from this reaction is the subject of this report. The half "solvent" molecule excluded from the structure had a total number of 30.7 electrons which is approximately half the total number of electrons that acetophenone has. Compound (I) crystallizes with two half molecules in the assymetric unit. The compound is dinuclear with each of the Cu atoms coordinated to four O atoms and a N atom from the pyrazole ligand. The O atoms are from acetate ions, all in the equatorial positions of a slightly distorted octahedral geometry around the Cu atoms. The N atom is bound trans to the Cu—Cu vector completing a the distorted octahedral geometry as axial ligands. The crystal structure of (I) is composed of two N—H···O hydrogen bonded chains (Table 1) that extend in the crystallographic b axis (Fig. 2).
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A structural study of palladium complexes containing hemilabile ligands
- Authors: Thompson, Catharine
- Date: 2012-09-06
- Subjects: Palladium compounds , Chemical reactions , Ligands , Catalysis , Catalysts
- Type: Thesis
- Identifier: uj:9678 , http://hdl.handle.net/10210/7092
- Description: D.Phil. , Palladium chemistry has advanced dramatically in the last few years, with a huge number of wide-ranging studies, particularly with respect to the application of palladium complexes as catalysts, having been performed. The discovery of the phenomenon of hemilability (the ability of a ligand to be bidentately coordinated but with one donor atom more weakly bound and thus able to decoordinate in the presence of a catalytic substrate) has further assisted the growth, since it has allowed a greater understanding of the mechanisms of catalytic-reactions. However, the focus of much of this work has been on ligands containing phosphorus and oxygen as potential donor atoms, with little attention being turned to ligands with other donor atoms. The current study concentrates on a series of palladium complexes containing potentially hemilabile thioether, selenoether and telluroether carboxylate ligands with the oxygen as the strongly coordinating atom. Each complex was completed by the palladium coordinating to a phenyl ligand trans to the oxygen of the hemilabile ligand and either one or two triphenylphosphine ligands, depending on whether or not the -hemilabile ligand was monodentately or bidentately coordinated. These complexes are of interest as possible catalysts for the oligomerisation of ethene, and had been previously synthesised and characterised by NMR spectroscopy, mass spectrometry and catalytic studies. In the current work the crystal and molecular structures of the various complexes were determined. Since a number of pairs of complexes containing the monodentate and bidentate forms of the ligands were identified the hemilability of the ligands was confirmed.
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- Authors: Thompson, Catharine
- Date: 2012-09-06
- Subjects: Palladium compounds , Chemical reactions , Ligands , Catalysis , Catalysts
- Type: Thesis
- Identifier: uj:9678 , http://hdl.handle.net/10210/7092
- Description: D.Phil. , Palladium chemistry has advanced dramatically in the last few years, with a huge number of wide-ranging studies, particularly with respect to the application of palladium complexes as catalysts, having been performed. The discovery of the phenomenon of hemilability (the ability of a ligand to be bidentately coordinated but with one donor atom more weakly bound and thus able to decoordinate in the presence of a catalytic substrate) has further assisted the growth, since it has allowed a greater understanding of the mechanisms of catalytic-reactions. However, the focus of much of this work has been on ligands containing phosphorus and oxygen as potential donor atoms, with little attention being turned to ligands with other donor atoms. The current study concentrates on a series of palladium complexes containing potentially hemilabile thioether, selenoether and telluroether carboxylate ligands with the oxygen as the strongly coordinating atom. Each complex was completed by the palladium coordinating to a phenyl ligand trans to the oxygen of the hemilabile ligand and either one or two triphenylphosphine ligands, depending on whether or not the -hemilabile ligand was monodentately or bidentately coordinated. These complexes are of interest as possible catalysts for the oligomerisation of ethene, and had been previously synthesised and characterised by NMR spectroscopy, mass spectrometry and catalytic studies. In the current work the crystal and molecular structures of the various complexes were determined. Since a number of pairs of complexes containing the monodentate and bidentate forms of the ligands were identified the hemilability of the ligands was confirmed.
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Ferrocene-derivatized dithiophosphonate salts and their gold(I) and palladium(II) complexes
- Authors: Pieterse, Hendriëtte
- Date: 2010-04-12T10:20:05Z
- Subjects: Ferrocene , Phosphonates , Salts , Gold compounds , Palladium compounds
- Type: Thesis
- Identifier: uj:6768 , http://hdl.handle.net/10210/3179
- Description: M.Sc. , The dimeric structure of Lawesson’s reagent, (RPS2)2 (R = 4–MeOC6H4), or its ferrocenyl analogue (R = ferrocenyl, Fc) leads to symmetrical cleavage through nucleophillic attack by alcohols to form dithiophosphonic acids, which can be readily deprotonated by ammonia to form the corresponding ammonium salts, which can be further reacted with transition-metal halides to form new metal complexes. Among the phosphor-1,1-dithiolates as a generic class of compounds, the dithiophosphates, [S2P(OR)2]-, have been most intensely studied and the dithiophosphonates [S2PR(OR’)]-, the subject of the present study, to a far lesser extent. In this study, a large variety of new dithiophosphonate salts were synthesized from diverse alcohol functionalities derived from cholesterol, estrone, estradiol, pentaerythritol, ethandiol, hydroquinone, resorcinol, glucose and ribose. The salts were oxidized with iodine to yield various S-S oxidative products, of which two X-ray crystal structures of such compounds, the ethandiol and pentaerythritol derivatives, were obtained and they were subjected to further investigation by cyclic voltammetry due to the ferrocenyl-rich functionalities they contain. The reaction of these [S2PR(OR’)]- type salts with a number of gold(I) and palladium(II) precursors, yielded a variety of new complexes. The compounds containing multiple alcohol (hydroxy) sites have been reacted with gold(I) and palladium(II) starting materials ClAu(tht) and PdCl2(PPh3)2, respectively and also with other gold(I) variants, including the mono- and dinuclear phosphines ClAuPPh3, Au2Cl2dppe and Au2Cl2dppa. A new X-ray single crystal structure of a gold(I) complex could be obtained as a decomposition product. New products have been characterized through a combination of solution 1H and 31P NMR, EIS mass spectrometry, IR, elemental analysis, electro-chemistry and single crystal X-ray crystallographic studies.
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- Authors: Pieterse, Hendriëtte
- Date: 2010-04-12T10:20:05Z
- Subjects: Ferrocene , Phosphonates , Salts , Gold compounds , Palladium compounds
- Type: Thesis
- Identifier: uj:6768 , http://hdl.handle.net/10210/3179
- Description: M.Sc. , The dimeric structure of Lawesson’s reagent, (RPS2)2 (R = 4–MeOC6H4), or its ferrocenyl analogue (R = ferrocenyl, Fc) leads to symmetrical cleavage through nucleophillic attack by alcohols to form dithiophosphonic acids, which can be readily deprotonated by ammonia to form the corresponding ammonium salts, which can be further reacted with transition-metal halides to form new metal complexes. Among the phosphor-1,1-dithiolates as a generic class of compounds, the dithiophosphates, [S2P(OR)2]-, have been most intensely studied and the dithiophosphonates [S2PR(OR’)]-, the subject of the present study, to a far lesser extent. In this study, a large variety of new dithiophosphonate salts were synthesized from diverse alcohol functionalities derived from cholesterol, estrone, estradiol, pentaerythritol, ethandiol, hydroquinone, resorcinol, glucose and ribose. The salts were oxidized with iodine to yield various S-S oxidative products, of which two X-ray crystal structures of such compounds, the ethandiol and pentaerythritol derivatives, were obtained and they were subjected to further investigation by cyclic voltammetry due to the ferrocenyl-rich functionalities they contain. The reaction of these [S2PR(OR’)]- type salts with a number of gold(I) and palladium(II) precursors, yielded a variety of new complexes. The compounds containing multiple alcohol (hydroxy) sites have been reacted with gold(I) and palladium(II) starting materials ClAu(tht) and PdCl2(PPh3)2, respectively and also with other gold(I) variants, including the mono- and dinuclear phosphines ClAuPPh3, Au2Cl2dppe and Au2Cl2dppa. A new X-ray single crystal structure of a gold(I) complex could be obtained as a decomposition product. New products have been characterized through a combination of solution 1H and 31P NMR, EIS mass spectrometry, IR, elemental analysis, electro-chemistry and single crystal X-ray crystallographic studies.
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Functionalised porphyrazines and their use in catalysis
- Authors: Tshivhase, Mmboneni Gifty
- Date: 2012-08-16
- Subjects: Catalysis , Porphyrins , Phthalocyanines , Palladium compounds , Heck reaction , Imidazoles , Ligands
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/367536 , uj:2573 , http://hdl.handle.net/10210/6024
- Description: D.Phil. , Porphyrazines like porphyrins and phthalocyanines have unique physical, chemical and spectral properties. This allows them to have many impressive applications. They are less studied than phthalocyanines because of the absence of convenient methods for their synthesis. However, recent studies, including this one, have made these compounds more accessible. The palladium-imidazolium salt systems have proved to be one of the most successful catalysts for the Heck and Suzuki coupling reactions. Substituents on nitrogen atoms of imidazolium significantly influence the catalytic activities of the corresponding palladiumimidazolium salt systems in the Heck and Suzuki coupling. The synthesis of the imidazolium salts is discussed in this study. The synthesis of the imidazoles started from diamines. A new route for the synthesis of 4,5-diaminophthalonitrile is discussed here and so far it is the most convenient and less tedious route with higher yields. The catalytic activities on different substrates have also been extensively investigated and gave impressive results, on the Heck and Suzuki reaction. The catalysis study was first performed using the dicyanoimidazolium salts and then with the imidazolium salts of the porphyrazines. The results indicate that both these systems are active ligands for Suzuki and Heck reactions. Two complexes, [1’,1’’-dibutyl-3’,3’’-(4,5-(1,2-dicyanobenzene))diimidazolium dibromide] and [2,3-benzo(2’,3’-(3’’,3’’’-dibutyldiimidazolium-2’,2’’-diylidene)palladium(II)- dibromide)-7,8,12,13,17,18-hexapropyl,porphyrazine] were synthesised successfully in good yields and used for Suzuki and Heck catalysis reactions. Catalyst recovery in homogeneous catalysis is always a major problem; this led this study to make use of porphyrazines in biphasic catalysis because of their high extinction coefficient which comes from their very intense colour. The reactions were performed in a combination of water with toluene and also water with ionic liquid. Both this systems gave results which proved that it is possible to separate the catalyst and the products once the reaction is complete. Two aminoporphyrazines and phthalonitriles were also synthesised in multistep synthesis. The synthesis involved a lot of protection and deprotection steps. These compounds are starting materials to aminophosphine ligands which have a wide variety of catalysis applications.
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- Authors: Tshivhase, Mmboneni Gifty
- Date: 2012-08-16
- Subjects: Catalysis , Porphyrins , Phthalocyanines , Palladium compounds , Heck reaction , Imidazoles , Ligands
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/367536 , uj:2573 , http://hdl.handle.net/10210/6024
- Description: D.Phil. , Porphyrazines like porphyrins and phthalocyanines have unique physical, chemical and spectral properties. This allows them to have many impressive applications. They are less studied than phthalocyanines because of the absence of convenient methods for their synthesis. However, recent studies, including this one, have made these compounds more accessible. The palladium-imidazolium salt systems have proved to be one of the most successful catalysts for the Heck and Suzuki coupling reactions. Substituents on nitrogen atoms of imidazolium significantly influence the catalytic activities of the corresponding palladiumimidazolium salt systems in the Heck and Suzuki coupling. The synthesis of the imidazolium salts is discussed in this study. The synthesis of the imidazoles started from diamines. A new route for the synthesis of 4,5-diaminophthalonitrile is discussed here and so far it is the most convenient and less tedious route with higher yields. The catalytic activities on different substrates have also been extensively investigated and gave impressive results, on the Heck and Suzuki reaction. The catalysis study was first performed using the dicyanoimidazolium salts and then with the imidazolium salts of the porphyrazines. The results indicate that both these systems are active ligands for Suzuki and Heck reactions. Two complexes, [1’,1’’-dibutyl-3’,3’’-(4,5-(1,2-dicyanobenzene))diimidazolium dibromide] and [2,3-benzo(2’,3’-(3’’,3’’’-dibutyldiimidazolium-2’,2’’-diylidene)palladium(II)- dibromide)-7,8,12,13,17,18-hexapropyl,porphyrazine] were synthesised successfully in good yields and used for Suzuki and Heck catalysis reactions. Catalyst recovery in homogeneous catalysis is always a major problem; this led this study to make use of porphyrazines in biphasic catalysis because of their high extinction coefficient which comes from their very intense colour. The reactions were performed in a combination of water with toluene and also water with ionic liquid. Both this systems gave results which proved that it is possible to separate the catalyst and the products once the reaction is complete. Two aminoporphyrazines and phthalonitriles were also synthesised in multistep synthesis. The synthesis involved a lot of protection and deprotection steps. These compounds are starting materials to aminophosphine ligands which have a wide variety of catalysis applications.
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Synthesis and evaluation of ferrocenylpyrazolyl and ferrocenylpyrazolyl-phosphine palladium and nickel complexes as ethylene oligomerization catalysts
- Authors: Van der Westhuizen, Arnoux
- Date: 2012-06-07
- Subjects: Palladium compounds , Nickel compounds
- Type: Thesis
- Identifier: uj:8680 , http://hdl.handle.net/10210/5035
- Description: M.Sc. , Several bis[1-ferrocenyl(ethyl)pyrazolyl palladium dichloro (complexes 1 and 3) and palladium chloromethyl complexes (complexes 2 and 4) have been synthesized by the reactions of 1- ferrocenyl(ethyl)-1N-pyrazole and 1-ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole with [PdCl2(NCMe)2] and [PdClMe(cod)] respectively. Furthermore, a library of phosphorus^nitrogen (P^N) ferrocenyl(ethyl)-amine and -pyrazolyl ligands have been successfully synthesized using the well known Ugi amine (compound 5) as intermediate. 1- [2-{diphenylphosphino}ferrocenyl](ethyl)amine and 1-[{2-diphenylphosphino}ferrocenyl](ethyl)- pyrazolyl Ni(II) and Pd(II) complexes were synthesized by reacting 1-[2- {diphenylphosphino}ferrocenyl](ethyl)dimethylamine, 1-[2-{diphenylphosphino}ferrocenyl](ethyl)- 1N-pyrazole and 1-[2-{diphenylphosphino}ferrocenyl](ethyl)-1N-(3,5-dimethyl)pyrazole with [NiCl2•6H2O] (compounds 12 and 16), [NiBr2(DME)] (compounds 13, 17 and 19), [PdCl2(NCMe)2] (compounds 10, 14, and 18) and [PdClMe(cod)] (compounds 11 and 15), respectively. 1-[2- {Diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole (compound 9) was synthesized by two distinct methodologies. In one method, 1-ferrocenyl(ethyl)dimethylamine was converted to 1-[2- {diphenylphosphino}ferrocenyl](ethyl)dimethylamine before it was subsequently reacted with 3,5- dimethylpyrazole to produce 1-[2-{diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole. In the other method, 1-ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole was converted to 1-[2- {diphenylphosphino}ferrocenyl](ethyl)-1N-(3,5-dimethyl)pyrazole before the reaction with 3,5- dimethylpyrazole, producing 1-[2-{diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole. These compounds synthesized via different methods as well as their palladium dichloro complexes show different structures in solution, but solid state structural analysis agrees on the same structure. The structural difference in solution is contributed to the high degree of flexibility at the stereogenic centre of the complex. The Ni(II) ferrocenyl phosphine complexes 12, 13, 16, 17 and 19 exist in equilibrium between diamagnetic square planar form and paramagnetic tetrahedral form. The tetrahedral geometry is xvi favoured over the square planar geometry, purely on steric grounds, but the square planar geometry occurs with d8 complexes because of the more favourable electronic situation of the complex. Activation of these P^N palladium and nickel ferrocenyl- amine and -pyrazolyl pre-catalysts 10, 12, 13, 14, 16, 17, 18a and 19 with EtAlCl2 results in the oligomerization of ethylene to C4 and C6 alkenes, followed by subsequent Friedel-Crafts alkylation of the toluene solvent. Moderate catalytic activities of up to 659 kg of alkylated toluene products.mol-1 Ni. h-1 were observed for catalyst 13 at 20 bar ethylene pressure. In general, the Ni(II) pre-catalysts were more active than the Pd(II) precatalyst.
- Full Text:
- Authors: Van der Westhuizen, Arnoux
- Date: 2012-06-07
- Subjects: Palladium compounds , Nickel compounds
- Type: Thesis
- Identifier: uj:8680 , http://hdl.handle.net/10210/5035
- Description: M.Sc. , Several bis[1-ferrocenyl(ethyl)pyrazolyl palladium dichloro (complexes 1 and 3) and palladium chloromethyl complexes (complexes 2 and 4) have been synthesized by the reactions of 1- ferrocenyl(ethyl)-1N-pyrazole and 1-ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole with [PdCl2(NCMe)2] and [PdClMe(cod)] respectively. Furthermore, a library of phosphorus^nitrogen (P^N) ferrocenyl(ethyl)-amine and -pyrazolyl ligands have been successfully synthesized using the well known Ugi amine (compound 5) as intermediate. 1- [2-{diphenylphosphino}ferrocenyl](ethyl)amine and 1-[{2-diphenylphosphino}ferrocenyl](ethyl)- pyrazolyl Ni(II) and Pd(II) complexes were synthesized by reacting 1-[2- {diphenylphosphino}ferrocenyl](ethyl)dimethylamine, 1-[2-{diphenylphosphino}ferrocenyl](ethyl)- 1N-pyrazole and 1-[2-{diphenylphosphino}ferrocenyl](ethyl)-1N-(3,5-dimethyl)pyrazole with [NiCl2•6H2O] (compounds 12 and 16), [NiBr2(DME)] (compounds 13, 17 and 19), [PdCl2(NCMe)2] (compounds 10, 14, and 18) and [PdClMe(cod)] (compounds 11 and 15), respectively. 1-[2- {Diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole (compound 9) was synthesized by two distinct methodologies. In one method, 1-ferrocenyl(ethyl)dimethylamine was converted to 1-[2- {diphenylphosphino}ferrocenyl](ethyl)dimethylamine before it was subsequently reacted with 3,5- dimethylpyrazole to produce 1-[2-{diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole. In the other method, 1-ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole was converted to 1-[2- {diphenylphosphino}ferrocenyl](ethyl)-1N-(3,5-dimethyl)pyrazole before the reaction with 3,5- dimethylpyrazole, producing 1-[2-{diphenylphosphino}ferrocenyl(ethyl)-1N-(3,5-dimethyl)pyrazole. These compounds synthesized via different methods as well as their palladium dichloro complexes show different structures in solution, but solid state structural analysis agrees on the same structure. The structural difference in solution is contributed to the high degree of flexibility at the stereogenic centre of the complex. The Ni(II) ferrocenyl phosphine complexes 12, 13, 16, 17 and 19 exist in equilibrium between diamagnetic square planar form and paramagnetic tetrahedral form. The tetrahedral geometry is xvi favoured over the square planar geometry, purely on steric grounds, but the square planar geometry occurs with d8 complexes because of the more favourable electronic situation of the complex. Activation of these P^N palladium and nickel ferrocenyl- amine and -pyrazolyl pre-catalysts 10, 12, 13, 14, 16, 17, 18a and 19 with EtAlCl2 results in the oligomerization of ethylene to C4 and C6 alkenes, followed by subsequent Friedel-Crafts alkylation of the toluene solvent. Moderate catalytic activities of up to 659 kg of alkylated toluene products.mol-1 Ni. h-1 were observed for catalyst 13 at 20 bar ethylene pressure. In general, the Ni(II) pre-catalysts were more active than the Pd(II) precatalyst.
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(Acetato-k2O,O)[2'-(di-tert-butylphosphanyl)- 1,1'-biphenyl-k2P,C2]- palladium(II)
- Arderne, Charmaine, Holzapfel, Cedric W.
- Authors: Arderne, Charmaine , Holzapfel, Cedric W.
- Date: 2012
- Subjects: Metal-organic compounds , Palladium compounds
- Type: Article
- Identifier: uj:5994 , ISSN 1600-5368 , http://hdl.handle.net/10210/8627
- Description: Please refer to full text to view abstract
- Full Text:
- Authors: Arderne, Charmaine , Holzapfel, Cedric W.
- Date: 2012
- Subjects: Metal-organic compounds , Palladium compounds
- Type: Article
- Identifier: uj:5994 , ISSN 1600-5368 , http://hdl.handle.net/10210/8627
- Description: Please refer to full text to view abstract
- Full Text:
Palladium, platinum and gold complexes: a synthetic approach towards the discovery of anticancer agents
- Authors: Keter, Frankline Kiplangat
- Date: 2010-03-10T06:28:55Z
- Subjects: Palladium compounds , Platinum compounds , Gold compounds , Complex compounds synthesis , Cancer treatment , Palladium - Therapeutic use , Gold - Therapeutic use , Platinum - Therapeutic use
- Type: Thesis
- Identifier: uj:6669 , http://hdl.handle.net/10210/3074
- Description: Ph.D. , Ligands bis(pyrazolyl)acetic acid (L1) and bis(3,5-dimethylpyrazolyl)acetic acid (L2) were synthesised by reacting pyrazoles and dibromoacetic acid under phase transfer conditions, by using benzyltriethylammonium chloride as the catalyst. Ligands L1 and L2 were characterised by a combination of 1H, 13C{1H} NMR, IR spectroscopy and microanalysis. Esterification of L1 and L2 led to formation of bis(pyrazolyl)ethyl acetate (L3) and bis(3,5-dimethylpyrazolyl)ethyl acetate (L4). Ligands L3 and L4 were also characterised by a combination of 1H, 13C{1H} NMR, IR spectroscopy and microanalysis. Subsequently, new pyrazolyl palladium(II) and platinum(II) compounds, [PdCl2(L1)] (1), [PdCl2(L2)] (2), [PtCl2(L1)] (3a) and [PtCl2(L2)] (4) were prepared by reacting bis(pyrazolyl)acetic acid ligands (L1-L2) with K2[PdCl4] or K2[PtCl4] respectively. The structures of complex 1 and 2 reveal distorted square planar geometries. The bond angles of N-Pd-N, N-Pd-Cl, N-Pd-Cl, for 1 and 2 are between 85.8(3)o and 90.81(4)o). The platinum compound, K2[Pt4Cl8(L1)2(deprotonated-L1)2].2H2O (3b), crystallised from aqueous solutions containing 3a when such solutions were left to stand overnight. Each platinum coordination environment consists of two cis-Cl ligands and one K2-N^N(L1) unit (L1 = bis(pyrazolyl)acetic acid), with two ligand moieties in 3b that are deprotonated with two K+ counter ions. Reaction of bis(pyrazolyl)acetic acid ligands (L1-L2) with [HAuCl4].4H2O gave gold(III) complexes [AuCl2(L1)]Cl (5a) and [AuCl2(L2)]Cl (6a). The spectroscopic, mass spectroscopy and microanalysis data were used to confirm the formation of the desired complexes. However, attempts to crystallise 5a and 6a led to formation of [AuCl2(pz)(pzH)] (5b) and [AuCl2(3,5-Me2pz)(3,5-Me2pzH)] (6b). This was confirmed by the structural characterisation of 5b, which has a distorted square-planar geometry. When complexes 1-6a were screened for their anti-tumour activity against CHO-22 cells, they showed no appreciable biological activities against CHO-22 cells. Substitution reactions of complexes 1-6a with L-cysteine performed to probe any relationship between the observed antitumour activities and the rates of ligand substitution of these complexes were inconclusive. Dithiocarbamate ligands L5-L8 were synthesised as potassium salts by introducing a CS2 group in positions 1 of pyrazole, 3,5-dimethylpyrazole, indazole and imidazole. The reaction of L5-L8 with [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)] and [Au2Cl2(dpph)], led to isolation of complexes [Au(L)(PPh3)] (13-16), [Au2(L)2(dppe)] (17a-19), [Au2(L)2(dppp)] (20-22) and [Au2(L)2(dpph)] (23-25) (dppe = bis(diphenylphosphino)ethane, dppp = bis(diphenylphosphino)propane, dpph = bis(diphenylphosphino)hexane; L = anions of L5-L8). The mononuclear molecular structure of 15 features a near linear geometry with a P(1)-Au(1)-S(1) angle of 175.36(2) o. The binuclear gold(I) complexes 20-22 and 23-25 have two P-Au-S moieties as evident in the solid state structure of 25. Attempts to crystallise complex 17a led to the formation of a gold(I) cluster complex [Au18S8(dppe)6]2+ (17b) as confirmed by X-ray crystallography. Cluster 17b features weak Au···Au interactions (2.9263(7)-3.1395(7) Å). Complexes 13-16 and 20-25 were tested in vitro for anticancer activity on HeLa cells. The activities of gold(I) complexes 13-16 were comparable to that of cisplatin. Dinuclear gold(I) complexes 20-25 also showed appreciable antitumour activity against HeLa cells. However, the dpph gold(I) compounds (23-25) were highly active, with 24 showing the highest activity against HeLa cells (IC50 = 0.1 μM). The tumour specificity (TS) factors for 23 and 24 were 31.0 and 70.5, respectively.
- Full Text:
- Authors: Keter, Frankline Kiplangat
- Date: 2010-03-10T06:28:55Z
- Subjects: Palladium compounds , Platinum compounds , Gold compounds , Complex compounds synthesis , Cancer treatment , Palladium - Therapeutic use , Gold - Therapeutic use , Platinum - Therapeutic use
- Type: Thesis
- Identifier: uj:6669 , http://hdl.handle.net/10210/3074
- Description: Ph.D. , Ligands bis(pyrazolyl)acetic acid (L1) and bis(3,5-dimethylpyrazolyl)acetic acid (L2) were synthesised by reacting pyrazoles and dibromoacetic acid under phase transfer conditions, by using benzyltriethylammonium chloride as the catalyst. Ligands L1 and L2 were characterised by a combination of 1H, 13C{1H} NMR, IR spectroscopy and microanalysis. Esterification of L1 and L2 led to formation of bis(pyrazolyl)ethyl acetate (L3) and bis(3,5-dimethylpyrazolyl)ethyl acetate (L4). Ligands L3 and L4 were also characterised by a combination of 1H, 13C{1H} NMR, IR spectroscopy and microanalysis. Subsequently, new pyrazolyl palladium(II) and platinum(II) compounds, [PdCl2(L1)] (1), [PdCl2(L2)] (2), [PtCl2(L1)] (3a) and [PtCl2(L2)] (4) were prepared by reacting bis(pyrazolyl)acetic acid ligands (L1-L2) with K2[PdCl4] or K2[PtCl4] respectively. The structures of complex 1 and 2 reveal distorted square planar geometries. The bond angles of N-Pd-N, N-Pd-Cl, N-Pd-Cl, for 1 and 2 are between 85.8(3)o and 90.81(4)o). The platinum compound, K2[Pt4Cl8(L1)2(deprotonated-L1)2].2H2O (3b), crystallised from aqueous solutions containing 3a when such solutions were left to stand overnight. Each platinum coordination environment consists of two cis-Cl ligands and one K2-N^N(L1) unit (L1 = bis(pyrazolyl)acetic acid), with two ligand moieties in 3b that are deprotonated with two K+ counter ions. Reaction of bis(pyrazolyl)acetic acid ligands (L1-L2) with [HAuCl4].4H2O gave gold(III) complexes [AuCl2(L1)]Cl (5a) and [AuCl2(L2)]Cl (6a). The spectroscopic, mass spectroscopy and microanalysis data were used to confirm the formation of the desired complexes. However, attempts to crystallise 5a and 6a led to formation of [AuCl2(pz)(pzH)] (5b) and [AuCl2(3,5-Me2pz)(3,5-Me2pzH)] (6b). This was confirmed by the structural characterisation of 5b, which has a distorted square-planar geometry. When complexes 1-6a were screened for their anti-tumour activity against CHO-22 cells, they showed no appreciable biological activities against CHO-22 cells. Substitution reactions of complexes 1-6a with L-cysteine performed to probe any relationship between the observed antitumour activities and the rates of ligand substitution of these complexes were inconclusive. Dithiocarbamate ligands L5-L8 were synthesised as potassium salts by introducing a CS2 group in positions 1 of pyrazole, 3,5-dimethylpyrazole, indazole and imidazole. The reaction of L5-L8 with [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)] and [Au2Cl2(dpph)], led to isolation of complexes [Au(L)(PPh3)] (13-16), [Au2(L)2(dppe)] (17a-19), [Au2(L)2(dppp)] (20-22) and [Au2(L)2(dpph)] (23-25) (dppe = bis(diphenylphosphino)ethane, dppp = bis(diphenylphosphino)propane, dpph = bis(diphenylphosphino)hexane; L = anions of L5-L8). The mononuclear molecular structure of 15 features a near linear geometry with a P(1)-Au(1)-S(1) angle of 175.36(2) o. The binuclear gold(I) complexes 20-22 and 23-25 have two P-Au-S moieties as evident in the solid state structure of 25. Attempts to crystallise complex 17a led to the formation of a gold(I) cluster complex [Au18S8(dppe)6]2+ (17b) as confirmed by X-ray crystallography. Cluster 17b features weak Au···Au interactions (2.9263(7)-3.1395(7) Å). Complexes 13-16 and 20-25 were tested in vitro for anticancer activity on HeLa cells. The activities of gold(I) complexes 13-16 were comparable to that of cisplatin. Dinuclear gold(I) complexes 20-25 also showed appreciable antitumour activity against HeLa cells. However, the dpph gold(I) compounds (23-25) were highly active, with 24 showing the highest activity against HeLa cells (IC50 = 0.1 μM). The tumour specificity (TS) factors for 23 and 24 were 31.0 and 70.5, respectively.
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Nitrogen-based nickel and palladium complexes as catalysts for olefin oligomerization, Heck and Suzuki coupling reactions
- Authors: Nelana, Simphiwe Maurice
- Date: 2009-03-31T09:40:18Z
- Subjects: Nickel compounds , Nickel catalysts , Palladium compounds , Palladium catalysts , Alkenes , Transition metal compounds synthesis
- Type: Thesis
- Identifier: uj:8272 , http://hdl.handle.net/10210/2381
- Description: Ph.D. , This thesis deals with the synthesis of nitrogen-donor compounds and their reaction with metal ions. The first type of nitrogen-donor compounds are the unconjugated diimines (N,N´-bis(diphenylmethylene)ethylenediamine (L1) and (N,N´-bis(diphenylmethylene)propylenediamine (L2). Compounds L1 and L2 were reacted with [NiBr2(DME)] or [NiCl2·6H2O] to form complexes (2.1a), (2.2a), (2.3a) and (2.4a). These nickel complexes were characterized by IR spectroscopy, elemental analysis and mass spectrometry. When the complexes were left in chloroform for prolonged periods, hydrolysis of the diimine ligand took place, leading to the formation of nickel complexes 2.1b, 2.2b, 2.3b and 2.4b. The identity of the hydrolysed nickel complexes 2.1b and 2.2b was confirmed by single crystal X-ray crystallography. Complex 2.1b crystallised in the P21/n space group, whilst 2.2b crystallised in the P-1 space group. Compounds L1 and L2 were also reacted with [PdClMe(MeCN)2] to form the palladium complexes (3.1) and (3.2). The palladium complexes were characterized by NMR spectroscopy, elemental analysis and single crystal X-ray crystallography. Attempts to recrystallize 3.1 from a dichloromethane solution led to the formation of 3.1a. Both complexes 3.1a and 3.2 crystallised in the P21/n space group. Complexes 3.1 and 3.2 were tested as catalysts for the Heck coupling reaction of iodobenzene with methyl acrylate or butyl acrylate at 80 C. The products from the coupling reactions were characterized by GC and NMR spectroscopy. These complexes were found to be highly active with 100% conversions observed in some instances. The second type of ligands that were prepared are the benzoylpyrazolyl compounds, (3,5-dimethylpyrazol-1-yl)phenylmethanone (C1), (3,5-ditertiarybutylpyrazol-1-yl)phenylmethanone (C2), (3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone (C3), (3,5-ditertiarybutylpyrazol-1-yl)-o-toluoylmethanone (C4), (2-chlorophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C5), (2-chlorophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C6), (2-flourophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C7), (2-flourophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C8). These compounds were fully characterized using NMR spectroscopy, IR spectroscopy and elemental analysis. Compounds C1, C3, C5 and C7 were reacted with [NiBr2(DME)] to form nickel complexes (4.31-4.34). These nickel complexes were found to be insoluble in all common organic solvents and hence were characterized only by IR spectroscopy and elemental analysis. Compounds C1-C8 were also reacted with [PdCl2(MeCN)2] to form palladium complexes (4.35-4.42). Complexes 4.35-4.42 were characterized using NMR spectroscopy, IR spectroscopy, elemental analysis and in selected cases single crystal X-ray crystallography. Complex 4.39 crystallised in the C2/n space group and complex 4.42 crystallised in the P21/n space group. Attempts to recrystallize 4.37a led to the formation of 4.37b, which contains both 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone and 3,5-dimethylpyrazole as ligands. Complex 4.37b was confirmed by NMR spectroscopy and single crystal X-ray crystallography. Complex 4.37b crystallised in the Pbca space group. The formation of 4.37b is attributed to hydrolysis of 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone ligand in 4.37a due to the presence of adventitious water in the solvent. The palladium complexes (4.35-4.42) were tested as catalysts for the Heck coupling reaction of iodobenzene with butyl acrylate and also for the Suzuki coupling reaction of iodobenzene with phenylboronic acid or 4-chlorophenylboronic acid. In these reactions, complexes 4.35-4.42 were found to be highly active at 120 C. The pyrazolyl nickel and palladium complexes were further tested as catalysts in ethylene oligomerization reactions using EtAlCl2 as the co-catalyst. The nickel complexes were found to be the most active reaching TONs of 10.8105 g mol-1 h-1. The palladium analogues only gave TONs of up to 3.9105 g mol-1 h-1. The oligomers were characterized by GC and NMR spectroscopy and were found to be in the C10-C16 range, with C16 the most abundant olefin.
- Full Text:
- Authors: Nelana, Simphiwe Maurice
- Date: 2009-03-31T09:40:18Z
- Subjects: Nickel compounds , Nickel catalysts , Palladium compounds , Palladium catalysts , Alkenes , Transition metal compounds synthesis
- Type: Thesis
- Identifier: uj:8272 , http://hdl.handle.net/10210/2381
- Description: Ph.D. , This thesis deals with the synthesis of nitrogen-donor compounds and their reaction with metal ions. The first type of nitrogen-donor compounds are the unconjugated diimines (N,N´-bis(diphenylmethylene)ethylenediamine (L1) and (N,N´-bis(diphenylmethylene)propylenediamine (L2). Compounds L1 and L2 were reacted with [NiBr2(DME)] or [NiCl2·6H2O] to form complexes (2.1a), (2.2a), (2.3a) and (2.4a). These nickel complexes were characterized by IR spectroscopy, elemental analysis and mass spectrometry. When the complexes were left in chloroform for prolonged periods, hydrolysis of the diimine ligand took place, leading to the formation of nickel complexes 2.1b, 2.2b, 2.3b and 2.4b. The identity of the hydrolysed nickel complexes 2.1b and 2.2b was confirmed by single crystal X-ray crystallography. Complex 2.1b crystallised in the P21/n space group, whilst 2.2b crystallised in the P-1 space group. Compounds L1 and L2 were also reacted with [PdClMe(MeCN)2] to form the palladium complexes (3.1) and (3.2). The palladium complexes were characterized by NMR spectroscopy, elemental analysis and single crystal X-ray crystallography. Attempts to recrystallize 3.1 from a dichloromethane solution led to the formation of 3.1a. Both complexes 3.1a and 3.2 crystallised in the P21/n space group. Complexes 3.1 and 3.2 were tested as catalysts for the Heck coupling reaction of iodobenzene with methyl acrylate or butyl acrylate at 80 C. The products from the coupling reactions were characterized by GC and NMR spectroscopy. These complexes were found to be highly active with 100% conversions observed in some instances. The second type of ligands that were prepared are the benzoylpyrazolyl compounds, (3,5-dimethylpyrazol-1-yl)phenylmethanone (C1), (3,5-ditertiarybutylpyrazol-1-yl)phenylmethanone (C2), (3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone (C3), (3,5-ditertiarybutylpyrazol-1-yl)-o-toluoylmethanone (C4), (2-chlorophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C5), (2-chlorophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C6), (2-flourophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C7), (2-flourophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C8). These compounds were fully characterized using NMR spectroscopy, IR spectroscopy and elemental analysis. Compounds C1, C3, C5 and C7 were reacted with [NiBr2(DME)] to form nickel complexes (4.31-4.34). These nickel complexes were found to be insoluble in all common organic solvents and hence were characterized only by IR spectroscopy and elemental analysis. Compounds C1-C8 were also reacted with [PdCl2(MeCN)2] to form palladium complexes (4.35-4.42). Complexes 4.35-4.42 were characterized using NMR spectroscopy, IR spectroscopy, elemental analysis and in selected cases single crystal X-ray crystallography. Complex 4.39 crystallised in the C2/n space group and complex 4.42 crystallised in the P21/n space group. Attempts to recrystallize 4.37a led to the formation of 4.37b, which contains both 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone and 3,5-dimethylpyrazole as ligands. Complex 4.37b was confirmed by NMR spectroscopy and single crystal X-ray crystallography. Complex 4.37b crystallised in the Pbca space group. The formation of 4.37b is attributed to hydrolysis of 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone ligand in 4.37a due to the presence of adventitious water in the solvent. The palladium complexes (4.35-4.42) were tested as catalysts for the Heck coupling reaction of iodobenzene with butyl acrylate and also for the Suzuki coupling reaction of iodobenzene with phenylboronic acid or 4-chlorophenylboronic acid. In these reactions, complexes 4.35-4.42 were found to be highly active at 120 C. The pyrazolyl nickel and palladium complexes were further tested as catalysts in ethylene oligomerization reactions using EtAlCl2 as the co-catalyst. The nickel complexes were found to be the most active reaching TONs of 10.8105 g mol-1 h-1. The palladium analogues only gave TONs of up to 3.9105 g mol-1 h-1. The oligomers were characterized by GC and NMR spectroscopy and were found to be in the C10-C16 range, with C16 the most abundant olefin.
- Full Text:
trans-Dichloridobis{[4-(dimethylamino)- phenyl]diphenylphosphane}palladium(II)
- Muller, Alfred, Meijboom, Reinout
- Authors: Muller, Alfred , Meijboom, Reinout
- Date: 2010
- Subjects: X-ray crystallography , Crystallography , Transition metal complexes , Palladium compounds
- Type: Article
- Identifier: uj:5921 , ISSN 1600-5368 , http://hdl.handle.net/10210/8101
- Description: Please refer to full text to view abstract
- Full Text:
- Authors: Muller, Alfred , Meijboom, Reinout
- Date: 2010
- Subjects: X-ray crystallography , Crystallography , Transition metal complexes , Palladium compounds
- Type: Article
- Identifier: uj:5921 , ISSN 1600-5368 , http://hdl.handle.net/10210/8101
- Description: Please refer to full text to view abstract
- Full Text:
Nitrogen-donor nickel and palladium complexes as olefin transformation catalysts
- Authors: Ojwach, Stephen Otieno
- Date: 2009-04-30T10:05:35Z
- Subjects: Alkenes , Transition metal catalysts , Transition metal compounds , Nickel compounds , Palladium compounds , Complex compounds synthesis
- Type: Thesis
- Identifier: uj:8340 , http://hdl.handle.net/10210/2466
- Description: Ph.D. , Compounds, 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2,6-bis(3,5-ditertbutylpyrazol-1-ylmethyl)pyridine (L2) were prepared by phase transfer alkylation of 2,6-bis(bromomethyl)pyridine with two mole equivalents of the appropriate pyrazole. Ligands L1 and L2 reacted with either [PdCl2(NCMe)2] or [PdClMe(COD)] to form mononuclear palladium complexes [(PdCl2(L1)] (1), [(PdClMe(L1)] (2), [(PdCl2(L2)] (3), [(PdClMe(L2)] (4). All new compounds prepared were characterised by a combination of 1H NMR, 13C NMR spectroscopy and microanalyses. The coordination of L2 in a bidentate fashion through the pyridine nitrogen atom and one pyrazolyl nitrogen atom has been confirmed by single crystal X-ray crystallography of complex 3. Reactions of 1, 2 and 3 with the halide abstractor NaBAr4 (Ar = 3,5-(CF3)2C6H3) led to the formation of the stable tridentate cationic species [(PdCl(L1)]BAr4 (5), [(PdMe(L1)]BAr4 (6) and [(PdCl(L2)]BAr4 (7) respectively. Tridentate coordination of L1 and L2 in the cationic complexes has also been confirmed by single X-ray crystallography of complexes 5 and 6. The analogous carbonyl linker cationic species, [Pd{(3,5-Me2pz-CO)2-py}Cl]+ (9) and [Pd{(3,5-tBu2pz-CO)2-py}Cl]+ (10), prepared by halide abstraction from [Pd{(3,5-Me2pz-CO)2-py}Cl2] and [Pd{(3,5-tBu2pz-CO)2-py}Cl2] with NaBAr4, were however less stable. While cationic complexes 5-7 showed indefinite stability in solution, 9 and 10 had t1/2 of 14 and 2 days respectively. Attempts to crystallise 1 and 3 from the mother liquor resulted in the isolation of the salts [PdCl(L1)]2[Pd2Cl6] (11) and [PdCl(L2)]2[Pd2Cl6] (12). Although when complexes 1-4 xviii were reacted with modified methylaluminoxane (MMAO) or NaBAr4, no active catalysts for ethylene oligomerisation or polymerisation were formed, activation with silver triflate (AgOTf) produced active catalysts that oligomerised and polymerised phenylacetylene to a mixture of cis-transoidal and trans-cisoidal polyphenylacetylene. Compounds 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L3) and 2-(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L4) were prepared by phase transfer alkylation of 2-picolylchloride hydrochloride with one mole equivalent of the appropriate pyrazole. Compounds 2-(3,5-bis-trifluoromethyl-pyrazol-1-ylmethyl)-6-(3,5-dimethyl-pyrazol-1-ylmethyl)-pyridine (L5) and 2-(3,5-dimethyl-pyrazol-1-ylmethyl)-6-phenoxymethyl-pyridine (L6) were isolated in good yields by reacting (2-chloromethyl-6-3,5-dimethylpyrazol-1-ylmethyl)pyridine with an equivalent amount of potassium salt of 3,5-bis(trifluoromethyl)pyrazolate and potassium phenolate respectively. L3-L6 react with either [Pd(NCMe)2Cl2] or [PdClMe(COD)] to give mononuclear palladium complexes 13-18 of the general formulae [PdCl2(L)] or [PdClMe(L)] where L = is the bidentate ligands L3, L4, L5 and L6 respectively. Single crystal X-ray crystallography of complexes 13, 15 and 16 has been used to confirm the solid state geometry of the complexes. In attempts to generate active olefin oligomerisation catalysts, the chloromethyl Pd(II) complexes 14 and 16 were reacted with the halide abstractor NaBAr4 in the presence of stabilising solvents (i.e Et2O or NCMe) but no catalytic activities were observed. Decomposition was evident as observed from the deposition of palladium black in experiments using Et2O. In experiments where NCMe was used as the stabilising solvent, the formation of cationic species stabilised by NCMe was evident from 1H NMR analyses. Reaction of complex 14 with NaBAr4 on a preparative scale in a mixture of CH2Cl2 and NCMe solvent gave the cationic complex [[PdMeNCMe(L3)]BAr4 (19) in good yields. Complex 17 reacted with NABAr4 to give tridentate cationic species [[PdMe(L5)]BAr4 (20) which is inactive towards ethylene oligomerisation or polymerisation reactions. The tridentate coordination of L5 in 20 has also been established by single crystal X-ray structure of 20. Catalysts generated from 18 and 19 catalysed ethylene polymerisation at high pressures to branched polyethylene; albeit with very low activity. The Choromethyl palladium complex 14 reacted with sulfur dioxide to form complex 21. The nature of the product has been established by 1H NMR, 13C NMR and mass spectrometry to be an insertion product of SO2 into the Pd-Me bond of 14. Compounds L1-L4 reacted with the nickel salts NiCl2 or NiBr2 in a 1:1 mole ratio to give the nickel complexes [NiCl2(L1)] (22), [NiBr2(L1)] (23), [NiCl2(L2)] (24), and [NiBr2(L2)] (25), [Ni2(μ2-Cl)2Cl2(L3)2] (26), [Ni2(μ2-Br)2Br2(L3)2] (27), [NiCl2(L4)] (29) and [NiBr2(L4)] (30) in good yields. Reaction of L3 with NiBr2 in a 2:1 mole gave the octahedral complex [NiBr2(L4)2] (28) in good yields. Complexes 22-30 were characterised by a combination micro-analyses, mass spectrometry and single crystal X-ray analyses for 27 and 30. No NMR data were acquired because of the paramagnetic nature of the complexes. When complexes 22-30 were activated with EtAlCl2, highly active olefin oligomerisation catalysts were formed. In the ethylene oligomeristion reactions, three oligomers: C11, C14 xx and C16 were identified as the major products. Selectivityof 40% towards α-olefins were generally obtained. In general catalysts that contain the bidentate ligands L3 and L4 were more active than those that contain the tridentate ligands L1 and L2. Dichloride complexes exhibited relatively higher catalytic activities than their dibromide analogues. Turn over numbers (TON) for oligomer formation showed high dependence on ethylene concentration. A Lineweaver-Burk analysis of reactions catalysed by 22 and 26 showed TON saturation of 28 393 kg oligomer/mol Ni.h and 19 000 kg oligomer/mol Ni.h respectively. Catalysts generated from complexes 22-30 also catalysed oligomerisation of the higher olefins, 1-pentene, 1-hexene and 1-heptene and displayed good catalytic activities. Only two products C12 and C15 were obtained in the 1-pentene oligomerisation reactions. The 1-hexene reactions also gave two products, C12 and C18, while 1-heptene oligomerisation reactions gave predominantly C14 oligomers. Five benzoazoles were used to prepare a series of palladium complexes that were invesitigated as Heck coupling catalysts. The compounds 2-pyridin-2-yl-1H-benzoimidazole (L7) and 2-pyridin-2-yl-benzothiazole (L8) were prepared following literature procedures. The new ligands 2-(4-tert-butylpyridin-2-yl)-benzooxazole (L9) and 2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L10) were prepared by ring closure of aminophenol and aminothiophenol with tert-butyl picolinic acid respectively. The ligand 6-tert-Butyl-2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L11) was prepared by intramolecular cyclisation under basic conditions is described. Reactions of L7-L11 with either [Pd(NCMe)2Cl2] or [Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes [PdClMe(L7)] (31), [PdClMe(L8)] (32), [PdCl2(L9)] (33), [PdMeCl(L9)] (34), [PdCl2(L10)] (5), [PdMeCl(L10)] (36) and [PdMeCl(L11)] (37) as xxi confirmed by mass spectrometry and micro-analyses. The palladium complexes 31-37 were efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions and showed good stability.
- Full Text:
- Authors: Ojwach, Stephen Otieno
- Date: 2009-04-30T10:05:35Z
- Subjects: Alkenes , Transition metal catalysts , Transition metal compounds , Nickel compounds , Palladium compounds , Complex compounds synthesis
- Type: Thesis
- Identifier: uj:8340 , http://hdl.handle.net/10210/2466
- Description: Ph.D. , Compounds, 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2,6-bis(3,5-ditertbutylpyrazol-1-ylmethyl)pyridine (L2) were prepared by phase transfer alkylation of 2,6-bis(bromomethyl)pyridine with two mole equivalents of the appropriate pyrazole. Ligands L1 and L2 reacted with either [PdCl2(NCMe)2] or [PdClMe(COD)] to form mononuclear palladium complexes [(PdCl2(L1)] (1), [(PdClMe(L1)] (2), [(PdCl2(L2)] (3), [(PdClMe(L2)] (4). All new compounds prepared were characterised by a combination of 1H NMR, 13C NMR spectroscopy and microanalyses. The coordination of L2 in a bidentate fashion through the pyridine nitrogen atom and one pyrazolyl nitrogen atom has been confirmed by single crystal X-ray crystallography of complex 3. Reactions of 1, 2 and 3 with the halide abstractor NaBAr4 (Ar = 3,5-(CF3)2C6H3) led to the formation of the stable tridentate cationic species [(PdCl(L1)]BAr4 (5), [(PdMe(L1)]BAr4 (6) and [(PdCl(L2)]BAr4 (7) respectively. Tridentate coordination of L1 and L2 in the cationic complexes has also been confirmed by single X-ray crystallography of complexes 5 and 6. The analogous carbonyl linker cationic species, [Pd{(3,5-Me2pz-CO)2-py}Cl]+ (9) and [Pd{(3,5-tBu2pz-CO)2-py}Cl]+ (10), prepared by halide abstraction from [Pd{(3,5-Me2pz-CO)2-py}Cl2] and [Pd{(3,5-tBu2pz-CO)2-py}Cl2] with NaBAr4, were however less stable. While cationic complexes 5-7 showed indefinite stability in solution, 9 and 10 had t1/2 of 14 and 2 days respectively. Attempts to crystallise 1 and 3 from the mother liquor resulted in the isolation of the salts [PdCl(L1)]2[Pd2Cl6] (11) and [PdCl(L2)]2[Pd2Cl6] (12). Although when complexes 1-4 xviii were reacted with modified methylaluminoxane (MMAO) or NaBAr4, no active catalysts for ethylene oligomerisation or polymerisation were formed, activation with silver triflate (AgOTf) produced active catalysts that oligomerised and polymerised phenylacetylene to a mixture of cis-transoidal and trans-cisoidal polyphenylacetylene. Compounds 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L3) and 2-(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L4) were prepared by phase transfer alkylation of 2-picolylchloride hydrochloride with one mole equivalent of the appropriate pyrazole. Compounds 2-(3,5-bis-trifluoromethyl-pyrazol-1-ylmethyl)-6-(3,5-dimethyl-pyrazol-1-ylmethyl)-pyridine (L5) and 2-(3,5-dimethyl-pyrazol-1-ylmethyl)-6-phenoxymethyl-pyridine (L6) were isolated in good yields by reacting (2-chloromethyl-6-3,5-dimethylpyrazol-1-ylmethyl)pyridine with an equivalent amount of potassium salt of 3,5-bis(trifluoromethyl)pyrazolate and potassium phenolate respectively. L3-L6 react with either [Pd(NCMe)2Cl2] or [PdClMe(COD)] to give mononuclear palladium complexes 13-18 of the general formulae [PdCl2(L)] or [PdClMe(L)] where L = is the bidentate ligands L3, L4, L5 and L6 respectively. Single crystal X-ray crystallography of complexes 13, 15 and 16 has been used to confirm the solid state geometry of the complexes. In attempts to generate active olefin oligomerisation catalysts, the chloromethyl Pd(II) complexes 14 and 16 were reacted with the halide abstractor NaBAr4 in the presence of stabilising solvents (i.e Et2O or NCMe) but no catalytic activities were observed. Decomposition was evident as observed from the deposition of palladium black in experiments using Et2O. In experiments where NCMe was used as the stabilising solvent, the formation of cationic species stabilised by NCMe was evident from 1H NMR analyses. Reaction of complex 14 with NaBAr4 on a preparative scale in a mixture of CH2Cl2 and NCMe solvent gave the cationic complex [[PdMeNCMe(L3)]BAr4 (19) in good yields. Complex 17 reacted with NABAr4 to give tridentate cationic species [[PdMe(L5)]BAr4 (20) which is inactive towards ethylene oligomerisation or polymerisation reactions. The tridentate coordination of L5 in 20 has also been established by single crystal X-ray structure of 20. Catalysts generated from 18 and 19 catalysed ethylene polymerisation at high pressures to branched polyethylene; albeit with very low activity. The Choromethyl palladium complex 14 reacted with sulfur dioxide to form complex 21. The nature of the product has been established by 1H NMR, 13C NMR and mass spectrometry to be an insertion product of SO2 into the Pd-Me bond of 14. Compounds L1-L4 reacted with the nickel salts NiCl2 or NiBr2 in a 1:1 mole ratio to give the nickel complexes [NiCl2(L1)] (22), [NiBr2(L1)] (23), [NiCl2(L2)] (24), and [NiBr2(L2)] (25), [Ni2(μ2-Cl)2Cl2(L3)2] (26), [Ni2(μ2-Br)2Br2(L3)2] (27), [NiCl2(L4)] (29) and [NiBr2(L4)] (30) in good yields. Reaction of L3 with NiBr2 in a 2:1 mole gave the octahedral complex [NiBr2(L4)2] (28) in good yields. Complexes 22-30 were characterised by a combination micro-analyses, mass spectrometry and single crystal X-ray analyses for 27 and 30. No NMR data were acquired because of the paramagnetic nature of the complexes. When complexes 22-30 were activated with EtAlCl2, highly active olefin oligomerisation catalysts were formed. In the ethylene oligomeristion reactions, three oligomers: C11, C14 xx and C16 were identified as the major products. Selectivityof 40% towards α-olefins were generally obtained. In general catalysts that contain the bidentate ligands L3 and L4 were more active than those that contain the tridentate ligands L1 and L2. Dichloride complexes exhibited relatively higher catalytic activities than their dibromide analogues. Turn over numbers (TON) for oligomer formation showed high dependence on ethylene concentration. A Lineweaver-Burk analysis of reactions catalysed by 22 and 26 showed TON saturation of 28 393 kg oligomer/mol Ni.h and 19 000 kg oligomer/mol Ni.h respectively. Catalysts generated from complexes 22-30 also catalysed oligomerisation of the higher olefins, 1-pentene, 1-hexene and 1-heptene and displayed good catalytic activities. Only two products C12 and C15 were obtained in the 1-pentene oligomerisation reactions. The 1-hexene reactions also gave two products, C12 and C18, while 1-heptene oligomerisation reactions gave predominantly C14 oligomers. Five benzoazoles were used to prepare a series of palladium complexes that were invesitigated as Heck coupling catalysts. The compounds 2-pyridin-2-yl-1H-benzoimidazole (L7) and 2-pyridin-2-yl-benzothiazole (L8) were prepared following literature procedures. The new ligands 2-(4-tert-butylpyridin-2-yl)-benzooxazole (L9) and 2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L10) were prepared by ring closure of aminophenol and aminothiophenol with tert-butyl picolinic acid respectively. The ligand 6-tert-Butyl-2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L11) was prepared by intramolecular cyclisation under basic conditions is described. Reactions of L7-L11 with either [Pd(NCMe)2Cl2] or [Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes [PdClMe(L7)] (31), [PdClMe(L8)] (32), [PdCl2(L9)] (33), [PdMeCl(L9)] (34), [PdCl2(L10)] (5), [PdMeCl(L10)] (36) and [PdMeCl(L11)] (37) as xxi confirmed by mass spectrometry and micro-analyses. The palladium complexes 31-37 were efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions and showed good stability.
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