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 10.8105 g mol-1 h-1. The palladium analogues only gave TONs of up to 3.9105 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.

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.

M.Sc. (Chemistry) / This study deals with the synthesis of nitrogen-donor pyrazole- and pyrazolylethylamine compounds, their reactions with palladium(II) and nickel(II) precursors to form complexes and the applications of theses palladium(II) and nickel(II) complexes as catalysts for ethylene oligomerization reactions and reactions of higher α-olefins in Friedel-Crafts alkylation of aromatic solvents. A series of ligands, 3,5-di-tert-butyl-1H-pyrazole (L3), 3,5-diphenyl-1H-pyrazole (L4), 5-phenyl-3-(trifluoromethyl)-1H-pyrazole (L5) were synthesized using appropriate amounts of diketones and hydrazine hydrate; while ligands, 2-(1H-pyrazol-1-yl)ethylamine (L6), 2-(3,5-dimethyl-1H-pyrazol-1-yl)-ethylamine (L7), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)-ethylamine (L8), 2-(3,5-diphenyl-1H-pyrazol-1-yl)-ethylamine (L9) and 2-(5-phenyl-3-(trifluoromethyl)-1H-pyrazol-1-yl)ethylamine (L10) were prepared via the N sp3 alkylation of the corresponding pyrazoles with bromoethylamine Reactions of L1-L5 with [PdCl2(CNMe)2] formed five complexes of general formula [PdCl2 (L)2] {L = L1 (2.1), L2 (2.2), L3 (2.3), L4 (2.4) and L5 (2.5)}. Similarly [NiBr2(DME)] formed five complexes of general formula [NiBr2(L)2] {L = L1(2.6), L2 (2.7), L3 (2.8), L4 (2.9) and L5 (2.10)}. Complexes 2.1-2.10 were synthesized in a 2:1 mole ratio of ligand and metal precursor. Reactions of L6-L10 with [PdCl2(MeCN)2] yielded complexes 3.1-3.5 respectively. Ligands L6-L10 were also complexed with NiCl2.6H2O to give complex 3.6 while [NiCl2(DME)] and [NiBr2(DME)] gave complexes 3.7-3.8 and 3.9-3.13 respectively...

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.

No description available.

M.Sc. / This study describes the synthesis of pyrazolyl palladium and nickel complexes and their applications as catalysts for the co-polymerization of olefins with carbon monoxide and also as ethylene oligomerization catalysts. A series of compounds, 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-pyridin-2-ylmethylene-imine (L1), 2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl]-pyridin-2-ylmethylene-imine (L2), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-thiophen-2-ylmethylene-imine (L3), 2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl]-thiphen-2-ylmethylene-imine (L4), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-5-bromothiophen-2-ylmethylene-imine (L5), 2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl]-2bromothiophen-2-ylmethylene-imine (L6), 2-(3,5-dimethyl-pyrazol-1-yl)-ethyl]-pyrrol-2-ylmethylene-imine (L7) and 2-(3,5-di-tert-butyl-pyrazol-1-yl)-ethyl]-pyrrol-2-ylmethylene-imine (L8)] were prepared via Schiff base condensation of the appropriate amines and aldehydes. Reactions of L1-L6 and L8 with [PdClCH3(cod)] formed six complexes of general formula [PdClCH3(L)] {L = L1 (1), L2 (2), L3 (3), L4 (4), L5 (5) and L6 (6)} and [Pd(L8)2] (7). Complexes 1-6 were converted to the cationic compounds [PdCH3(L)]BAr4 {L = L1 (8), L2 (9), L3 (10), L4 (11), L5 (12) and L6 (13)} by the reaction of compounds 1-6 with the halide abstractor Na[BAr4] (where Ar = (3,5-(CF3)2C6H3) in a 1:1 mole ratio. For compounds 8 and 9 the cationic species were stabilized by the coordination of the pyrazolyl units of the ligands, which were uncoordinated in the parent palladium complexes 1 and 2. The cationic complexes 10-13, however, were stabilized by v coordination of NCCH3 to the palladium centre. Complexation of L1, L2, L5 and L6 with [PdCl2(NCCH3)2] gave the palladium dichloro complexes [PdCl2(L)], {L = L1 (14), L2 (15), L5 (16), and L6 (17)}. Compounds L1, L2, L7 and L8 were reduced to form compounds L9-L12 respectively and were reacted with [NiBr2DME] to form complexes [NiBr2(L)] {L = L9 (18), L10 (19), L11 (20) and L12 (21).

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.

During the attempts to carry out Suzuki coupling reactions, the σ-bonded Pd−Caryl benzochalcogenadiazolyl complexes trans-[ClPd(PPh3)2(C6H2BrN2E)] (E = S, Se) were isolated. The corresponding bromo derivatives were also synthesized on purpose to investigate their activity in Stille coupling reactions. A head-to-tail dimer trans- [{ClPd(PPh3)(μ-C6H2BrN2Se)}2] was synthesized from the thermolysis of trans- [ClPd(PPh3)2(C6H2BrN2Se)] in the presence of SeO2. The reduction potentials of the mononuclear and dinuclear complexes were measured by cyclic voltammetry (CV) and square wave voltammetry (SWV). 4,7-bis(2/4-pyridyl)benzochalcogenadiazole ligands were synthesized by Stille coupling reactions and the 1,5-bis(4-pyridyl)naphthalene ligand was prepared by a Suzuki coupling reaction. Reactions of the labile complex [BrRe(CO)4(NCMe)] with 4,7-bis(4- pyridyl)benzochalcogenadiazole ligands in a 2:1 ratio afforded self-assembled molecular rods [{ReBr(CO)4}2(μ-4,7-bis(4-pyridyl)benzochalcogenadiazoles)]. Palladium directed molecular squares [(enPd)(μ-4,7-bis(4-pyridyl)benzochalcogenadiazole)]4[PF6]8 were prepared by reactions of enPd(PF6)2 and 4,7-bis(4-pyridyl)benzochalco-genadiazoles in a 1:1 ratio. The optoelectronic properties of the ligands and the molecular rods were investigated by CV and SWV, and by luminescence spectroscopy. The optical properties of the square complexes were also studied by luminescence spectroscopy. / xvii, 152 leaves : ill. (some col.) ; 29 cm