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

Thesis (Ph. D.)--University of Washington. / Bibliography: L. [85]-88.

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.

No description available.

The synthesis, characterisation and X-ray structure detenninations of homonuclear nickel, palladium and platinum complexes with bis(phosphino)amine ligands is reviewed in Chapter 1. Particular attention is given to the mode of coordination that these ligands may adopt when coordinating to a transition metal i.e., as a monodentate (n'-), chelating (n2-) or bridging (u-) ligand. The Chapter is concluded with a brief summary of (i) The dependence of the 31P chemical shift for the bonded phosphorus atom(s) on the mode of coordination and (ii) The dependence of key, ligand-based, structural parameters on the mode of coordination. The synthesis and characterisation of the bis(diphenylphosphino )-ethylamine, Ph2PN(Et)PPh2, ligand and its subsequent reactions with various palladium precursors is described in Chapter 2. Reaction with the Pd(II) precursor, [PdCI2(PhCN)2], afforded the mononuclear complex cis-[PdCI2{ n2-Ph2PN(Et)PPh2}]1; when the same reaction was carried-out in the presence of the Pd(0) species [Pd2(dba)3] (dba = dibenzylideneacetone) the dinuclear ligand-bridged complex [Pd2C12 {u-Ph2PN(Et)PPh2}2] was formed. Reaction of 2 with I2 afforded 1, as well as the mononuclear di-iodo species cis-[PdI2 {n2-Ph2PN(Et)PPh2}] 3, and the mixed-halogeno complex [PdClI{n2-Ph2PN(Et)PPh2}] 4. Direct reaction of the ligand with [Pd2(dba)3] afforded, in the first instance, [Pd2{u-Ph2PN(Et)PPh2}3] 5, an extremely air-sensitive red compound, that readily reacted with oxygen in the solution to afford palladium metal and a yellow clathrate species that contained the oxidised ligand i.e., Ph2P(O)N(Et)P(O)PPh2. dba. H2O. Apart from 4, all compounds were characterised by means of elemental analysis, 1H and 3IP{1H} NMR spectroscopy and, in the case of 1, 2, 3 and Ph2P(O)N(Et)P(O)PPh2. dba. H2O, by means of single crystal X-ray structure determinations. The structures of the palladium complexes are, as expected, dominated by the requirement that the coordination geometry at the Pd atom is square-planar. In the case of the dinuclear ligand-bridged complex 2, this is achieved through formation of a Pd-Pd bond of length 2.600(1)A. Of particular interest is the crystal structure of the clathrate, which has the oxidised ligand and dba molecules stacked in alternating lines approximately parallel to the [c ]-axis of the unit cell. The synthesis and characterisation of the bis(2-pyridyl)phenylphosphine, PhP(py)2 ligand and its subsequent reaction with [PdCI2(PhCN)2] to afford the mononuclear complex cis-[PdCI2{n1-PhP(py)2}2] 6 is decribed in Chapter 3. The latter reacted with [Pd2(dba)3] to afford the dinuclear ligand-bridged species [Pd2CI2{u-PhP(py)2}2] 7. The 1H and 31P{1H} NMR spectral data, as well the results of single crystal X-ray structure determinations are reported for 6 and 7. The square-planar coordination at each palladium atom in 7 is achieved through the formation of a Pd-Pd bond of length 2.586(1)A. The synthesis and characterisation of the 2,5-(diphenylphosphino)thiophene, Ph2P(C4H2S)PPh2 ligand is described in Chapter 4. Reaction of the ligand with [PdCI2(PhCN)2] afforded the dinuclear ligand-bridged species [Pd2C14 {u-Ph2P(C4H2S)PPh2}2] 8. Characterisation of 8 was by means of elemental analysis, 1H and 31P{1H} NMR spectroscopy. Reaction of 8 with Ag+ in acetonitrile afforded a compound isolated as a yellow solid and formulated as [Pd2CI3(MeCN){u-Ph2P(C4H2S)PPh2}2] 9. Evidence for this formulation is based on the 31P{1H} NMR spectrum which shows two closely-spaced singlets, consistent with two sets of phosphorus atoms in different chemical environments, and too far separated (by 4 bonds) for magnetic coupling. Unfortunately, single crystals of these thienylphosphine ligand-bridged compounds could not be grown. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Thesis (Ph. D.)--University of Sydney, 2008. / Title from title screen (viewed June 19, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Biomedical Science, School of Medical Sciences, Faculty of Medicine. Degree awarded 2008; thesis submitted 2007. Includes bibliographical references. Also available in print form.

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.

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.

No description available.

The adsorption and separation of Pd(II) from Pt(IV), Ir(IV) and Rh(III) by silica microparticles functionalized with triethylenetetramine (TETA), 2-(2-aminoethylthio)ethanamine (NSN) and 2-(2-(2-aminoethyl)ethylthio)ethanamine (NSSN) in 1 M hydrochloric acid medium was investigated by continuous column studies. The functionalized sorbent materials were characterized by microanalysis, SEM-EDS and FT-IR. Palladium selectivity of the sorbent materials was achieved by stripping of rhodium, iridium and platinum chlorido species with 0.5 M of NaClO4 in 1 M HCl while [PdCl4]2 was eluted with 3% w/v thiourea. The desorption efficiency of thiourea was confirmed by the SEM-EDS analysis of the materials after Pd(II) elution. Palladium loading capacity of the sorbents were in the order S-NSSN (23.85 mg/g) > S-NSN (12.70 mg/g) > S-TETA (4.97 mg/g). The extraction patterns on the sorbent materials were explained by considering the coordination chemistry of the ligand with [PdCl4]2ˉ and ionic interactions of [PtCl6]2ˉ and [IrCl5(H2O]ˉ. The square planar complexes, [Pd(HNSSNH)Cl2]Cl2 and [Pd(NSNH)Cl2][PdCl4]2, were isolated, analyzed by spectroscopy and single crystal X-ray, whereas evidence of the fraction of Pd(II)-TETA complex was obtained by HPLC studies. This provided proof of the inner sphere coordination mechanism as the mode of interaction of these ligands with [PdCl4]2ˉ. Trace amounts of Brˉ anions in ligands resulted in the inadvertent isolation of bromide coordinated Pd(II) NSN and NSSN complexes. The ion-pair salts of [TETAH4]4+ with [PtCl6]2ˉ, [IrCl6]3ˉ and [RhCl6]3ˉ were also isolated and characterized by microanalysis and IR to further explain the extraction patterns.