The coordination behaviour of 4-aminoantipyrine (H2pap) and its Schiff base derivatives with the oxorhenium(V) and tricarbonyl rhenium(I) cores are reported. The reactions of trans-[ReOX3(PPh3)2] (X = Cl, Br) with H2pap were studied, and the complexes cis-[ReX2(pap)(H2pap)(PPh3)](ReO4) were isolated. The ligand pap is coordinated monodentately through the doubly deprotonated amino nitrogen as an imide, and H2pap acts as a neutral bidentate chelate, with coordination through the neutral amino nitrogen and the ketonic oxygen. The reactions of trans-[ReOBr3(PPh3)2] and cis-[ReO2I(PPh3)2] with -(2-aminobenzylideneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (H2nap) and 4-(2-hydroxybenzylideneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (Hoap) are also reported. The complexes cis-[Re(nap)Br2(PPh3)]Br, [ReO(OEt)(Hnap)(PPh3)]I and [ReO(OMe)(oap)(PPh3)]I were isolated and structurally characterized. The reactions of the Schiff base derivatives 1,2-(diimino-4’-antipyrinyl)ethane (dae) and 2,6-bis(4-amino-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one)pyridine (bap) with [Re(CO)5X] (X = Br or Cl) produced fac-[Re(CO)3(dae)Cl] and fac-[Re(CO)3(bap)Br] respectively. A series of rhenium(I) tricarbonyl complexes containing bidentate derivatives of aniline was synthesized and structurally characterized. With 1,2-diaminobenzene (Hpda) the ‘2+1’ complex salt fac-[Re(CO)3(κ1-Hpda)(κ2-Hpda)]Br was isolated, but with 2-mercaptophenol (Hspo) the bridged dimer [Re2(CO)7(spo)2] was found. The neutral complex [Re(CO)3(ons)(Hno)] was isolated from the reaction of [Re(CO)5Br] with 2-[(2-methylthio)benzylideneimino]phenol (Hons; Hno = 2-aminophenol), with ons coordinated as a bidentate chelate with a free SCH3 group. In the complex [Re(CO)3(Htpn)Br] (Htpn = N-(2-(methylthio)benzylidene)benzene-1,2-diamine) the potentially tridentate ligand Htpn is coordinated via the methylthiol sulfur and imino nitrogen atoms only, with a free amino group. These rhenium(I) complexes, with the exception of [Re2(CO)7(spo)2], revealed broad emissions centred around 535 nm. The reactions of the rhenium(V) complex cis-[ReO2I(PPh3)2] with 2-aminothiophenol (H2atp), benzene-1,2-dithiol (H2tdt) and 2-hydroxybenzenethiol (H2otp) led to the formation of the rhenium(III) compounds [Re(Hatp)(ibsq)2].OPPh3, [Re(sbsq)3].OPPh3 and [Re(obsq)3].OPPh3 (ibsq = 2-iminothiobenzosemiquinonate, sbsq = 1,2-dithiobenzosemiquinonate, obsq = 2-hydroxothiobenzosemiquinonate) respectively. The complexes adopt a trigonal prismatic geometry around the rhenium centre with average twists angles between 3.20-26.10˚. The E1/2 values for the Re(III)/Re(IV) redox couple were found to be 0.022, 0.142 and 0.126 V for [Re(Hatp)(ibsq)2].OPPh3, [Re(sbsq)3].OPPh3 and [Re(obsq)3].OPPh3 respectively. The reactions of the benzoxazole ligands, 3-(benzoxazol-2-yl)pyridin-2-ol (Hbop) and 5-amino-2-(benzoxazol-2-yl)phenol (Habo) with a [ReO]3+ precursor led to the rhenium(III) complex, [ReCl2(bop)(PPh3)2], and the complex salt, [ReO(abo)I(PPh3)2]ReO4, respectively. A variety of benzothiazole and benzimidazole derivatives were reacted with [Re(CO)5Br]. In the case of bis(benzothiazol-2-ylethyl)sulfide (bts), the neutral complex fac-[Re(CO)3(bts)Br] was obtained. The dimeric complexes (μ-dbt)2[Re(CO)3]2 and (μ-mbt)2[Re(CO)3]2 were formed when 1,3-bis(benzothiazol-2-yl)thiourea (Hdbt) and 1-(benzothiazol-2-ylidene)-3-methylthiourea (Hmbt) were used as ligands. The reaction of 2,2’-(oxybis(methylene))bis(benzimidazole) (bmb) with [Re(CO)5Cl] resulted in the rhenium(I) complex salt fac-[Re(CO)3(bmb)]+, with the tri-μ-chlorohexacarbonyl dirhenate [Re2(CO)6Cl3]- as the counter anion. The neutral complex fac-[Re(CO)3(btp)Cl] was isolated from the reaction of the 2,9-bis(benzothiazol-2-yl)-1,10-phenanthroline (btp) ligand and [Re(CO)5Cl]. The reactions of trans-[ReOCl3(PPh3)2] with bis(benzimidazol-2-ylethyl)sulfide (btn) and 1-(benzothiazol-2-ylidene)-3-methylthiourea (Hmbt) led to the formation of the cationic compounds (μ-O)2[Re2O2(btn)2]I2 and [ReCl2(bte)(PPh3)2]Cl (bte = (benzothiazole-2-yl)-N-ethylidenemethanamine) respectively.

Coordination properties of 4-bromo-N-(diethylcarbamothioyl)benzamide (Hbeb) and 4-bromo-N-(diphenylcarbamothioyl)benzamide (Hbpb) with oxorhenium(V) and rhenium(I) are reported and discussed. Transition metal complexes of these ligands were studied due to the wide range of applications of thiourea derivatives in biological fields. N-[Di(alkyl/aryl)carbamothioyl]benzamide derivatives readily coordinate to metal ions as O,S-donors and the catalytic property of the complexes can be altered by these ligands, due to steric and electronic properties provided by various substituents. The coordination possibilities of curcumin with rhenium(V) are discussed, as well as the difficulties encountered. Analogues of curcumin have been made, which also contains a seven-spacer unit between the phenyl rings, which would be more reactive and more effective in bonding to rhenium and which have greater or a similar biological activity to curcumin. This was done by assessing the coordination properties of 1,5-bis(salicylidene)thiocarbohydrazide (H4salt) and 2,4-bis(vanilidene)thiocarbohydrazide (H4vant) with oxorhenium(V) and rhenium(I) starting materials. Two rhenium(V) complex salts of the core [ReX(PPh3)2]4+ (X = Br, I), containing a coordinated imido nitrogen, are reported. One is a ‘2+1’ complex, coordinating bi- and monodentately, with the other a similar ‘3+0’ complex containing a tridentate imido-coordinated Schiff base. Selected compounds were tested against oesophageal cancer cell lines in order to evaluate and compare their effectiveness in eliminating or reducing the cancer cells in the test medium during biological testing.

It has long been observed that some organo-fluorine compounds exhibit enhanced biological activity over their non-fluorinated precursors, however reasons for these unusual properties still remain poorly understood. An explanation which has been widely used relates to the ability of the C-F fragment of the analog to participate in hydrogen-bonding interactions with its protein receptor. For this reason, fluorinated carbohydrates have been used as hydrogen-bonding probes with a number of proteins. Thus there exists a need for a systematic investigation into the hydrogen-bonding ability of the C-F fragment, and the enzyme glycogen phosphorylase provides an excellent subject for such a study. The glucopyranose binding site in the inactive (T-state) conformation of the enzyme has been well characterised and high resolution crystallographic data is available. Thus by comparison of kinetic and crystallographic data for the natural effectors and the fluorinated substrate analogs considerable insight into the hydrogen bonding ability of the C-F fragment and the nature of carbohydrate-protein interactions should be gained. Little is known about the active (R-state) conformation of the enzyme and about the T-state to R-state transition. Use of fluorinated analogs of the enzymes natural substrate, glucose-l-phosphate, could also shed light on these questions. With these aims in mind, all of the isomeric mono-fluorinated derivatives of glucose and glucose-l-phosphate have been synthesised. Some deoxy and difluorinated analogs of glucose and mannose have also been prepared. Kinetic results obtained using the analogs of glucose indicate that the 3 and 6 positions of the sugar participate in strong hydrogen-bonding interactions with the protein while the other positions are only involved in relatively weak interactions. These results agree well with recent X-ray crystallographic data. None of the analogs of glucose-l-phosphate exhibited any substrate activity. The 2-deoxyfluoro analog had a similar affinity to glucose-1-phosphate and therefore probably binds in the same mode. The lack of substrate activity in this case can be explained by the destabi1isation of the putative oxo-carbonium ion intermediate at C(l), by the adjacent fluorine substituent. The other analogs of glucose-l-phosphate showed lower affinity for the enzyme. The similar inhibition constants obtained for these compounds suggested a binding mode in which the glucopyranose ring contributes little to the overall binding energy. This has led to the proposal of a molecular mechanism for the T-state to R-state transition. / Science, Faculty of / Chemistry, Department of / Graduate

The reaction of sodium pyrazolide or sodium 3,5-dimethyl-pyrazolide with trimethyl gallium followed by reaction of the resultant adduct with 'ethanolamine' produces novel asymmetric tridentate ligands which are capable of either meridional or facial coordination in transition metal complexes. Na⁺('pz')⁻ + Me₃Ga THF> Na⁺[Me₃Ga ('pz’) ] ⁻ Na⁺[Me₃Ga ('pz’) ] ⁻+ R’ ₂NCH₂CH₂OH₂ > Na⁺L⁻ + MeH With R' = H, these ligands react with divalent transition metal ions to give octahedral bis-ligand complexes. However with R’ = Me, reaction with divalent transition metal ions produced either trigonal bipyramidal (R = Me) or binuclear five-coordinate (R = H) complexes. The asymmetric chelating gallate ligands reacted with Mn(CO)₅Br to give LMn(CO)₃ and with appropriate Gp VI carbonyl derivatives to give LM(CO)₃⁻ ( M = Cr, Mo, W). The carbonyl anions were found to be stereochemically non-rigid in solution and a mechanism for the fluxional process is proposed. Reaction of LM(CO)₃⁻(M = Mo, W) with various three-electron ligands gave derivatives of the form, LM(CO)₂T (T = NO, N₂Ph, C₃H₅ C₄H₇, C₇H₇, and CH₂SMe). A similar fluxional process (to that found in the carbonyl anions) was found in the complex, [Me₂Ga(pz)(OCH₂CH₂NH₂)] Mo(CO)₂(n³ -C₄H₇). In addition, the cycloheptatrienyl derivatives were found to be fluxional as a result of a rapidly rotating C₇H₇ ring. Depending on the nature of T, the LM(CO)₂T derivatives can exhibit both positional and conformational isomerism and this subject is discussed in detail. Reaction of Na⁺L⁻ (R = R'= Me) with Ni(NO)I and Cu(PPh₃)Br gave LNi(NO) and LCu(PPh₃) respectively. Both of these molecules were found to be fluxional in solution and a similar mechanism to that proposed for the Gp VI carbonyl ions is invoked to explain these fluxional processes. The compounds, LMn(NO)₂ and LFe(NO)₂ (19-electron) were prepared by reaction of Na+L- (R = R'= Me) with appropriate metal dinitrosyl precursors.and are the first of their type to be synthesized. Finally, reaction of Na+L- (R = R'= Me) with Mo(NO)₂Cl₂ gave LMo(NO)₂Cl. In additon to studies involving the ligand L, the pyrazolyl bridged dimers [Ni('pz’)(NO)]₂, [Fe('pz')(NO)₂]₂ and [Co('pz')(NO)₂]₂ were prepared and their reactivity towards nucleophiles studied. The π-allyl compounds [Me₂Ga (pz" )₂]M (C₃H₅) (M = Ni or Pd) and [Ni (pz") (C₃H₅) ]"₂were also prepared. All the prepared compounds were systematically characterized with uv-vis, ir and XH nmr spectroscopy as well as mass spectrometry. In addition, x-ray studies were carried out (by Dr. S. Rettig) on several of the prepared compounds and these data are correlated with other physical measurements. / Science, Faculty of / Chemistry, Department of / Graduate

M.Sc. (Chemistry) / Please refer to full text to view abstract

The ligand 1-oxa-4,8-diazacyclodecane ([10]aneN2O) was synthesised, along with the [special characters omitted] complexes. Bis-ligand complexes are formed with facial coordination of the ligand to the transition metals, with two nitrogen donors from each ligand forming an equatorial plane around the metal ion. The crystal structure of [special characters omitted] was determined, as is described. The copper(II), nickel(II) and palladium(II) complexes have been characterised by FAB MS, electronic spectroscopy, elemental analysis and where possible by NMR and EPR spectroscopy. The nickel(II) and copper(II) complexes have distorted octahedral geometries, while the palladium(II) complex has square planar geometry with no observable axial interaction from the ether donors. The redox characteristics of the complexes formed have been determined, and are described within. The synthesis of the novel tricyclic ligand, 7,16-dioxa-1,4,10,13- tetraazatricyclo[11.5.3.3]octadecane [special characters omitted] is described. The [special characters omitted] conplex has been synthesised and characterised. The complex gives an unusually stable [special characters omitted] complex compared to complexes where a similar donor set is present A novel template synthesis was utilised to synthesise the bicyclic ligand 1,2-bis(1-oxa-5,8-diazacyclodecanyl)ethane ([special characters omitted] earmuff). This synthesis involved reaction of secondary amines which are coordinated to a copper(II) ion, a method which to our knowledge has not been used before in the synthesis of macrocyclic ligands. The copper(II) complex synthesised during this reaction has been characterised, and the redox reactions have been examined. The synthesis of 17-oxa-1,4,8,11-tetraazabicyclo[6.6.5]tetradecane (bicyclo[12-12] [special characters omitted]) is reported. Copper(II) and nickeI(II) complexes of this ligand have been synthesised and characterised. The chloride ion substitution reaction of [Ni(bicyclo[12-12] [special characters omitted] has been examined. The reaction was found to have an inverse dependence on the acid concentration. A tentative mechanism has been proposed to explain the origin of the acid dependence. The equilibrium constant for this reaction, determined by visible spectrophotometry, was found to be [special characters omitted]. The cobalt(III) bis-ligand complex of the previously synthesised ligand, 8-aza-1,5- dithiacyclodecane ([special characters omitted]) was synthesised. Under the conditions used, two isomers were formed - a facially coordinate bis-ligand complex where the equatorial plane is defined by two sulfur and two nitrogen donors, and a more symmetrical isomer where all four sulfur donors are coordinated equatorially. Isomerisation of the unsymmetrical isomer to the symmetrical isomer occurs in solution. The [special characters omitted] complexes of the ligand 1,2-bis(8-aza-1,5-dithiacycIodecanyI)ethane ([special characters omitted] earmuff) were synthesised and characterised. The ligand coordinates to [special characters omitted] in a pseudo five coordinate manner as determined by NMR spectroscopy. A solvent molecule or anion is likely to be coordinated to the [special characters omitted] centre in order to achieve distorted octahedral coordination. The complexes were characterised by FAB MS, electronic spectroscopy, elemental analysis and ESR spectroscopy. Although the [special characters omitted] centre was found to be in the low spin state, the electron transfer self exchange rate constant could not be determined by NMR spectroscopy. The [special characters omitted] complex of this ligand was also synthesised and found to coordinate in a five coordinate manner. Evidence of axial coordination of nitrogen in the palladium complex was observed in the electronic spectrum, therefore a distorted square pyramidal geometry has been proposed for the [[special characters omitted] earmuff)] complex. The potentially binuclear ligand, 1,9-bis(4-aza-1,8-dithiacyclononane)-4,7-diaza-2,8-dionenonane, was synthesised and characterised. Preliminary results indicate that reaction with two equivalents of nickel(II) produced a binuclear complex. / Graduate

A dissertation submitted to the Faculty of Science, in partial fulfilment of the requirements for the award of Master of Science degree, University of the Witwatersrand, Johannesburg, 2018 / Three mixed-ligand metal-metal bonded complexes containing one unsymmetrical anionic bridging ligand were successfully synthesized and characterized as to their electrochemical and spectroscopic properties. The investigated mono-substituted diruthenium complexes have the general formula, Ru2(OAc)3(L)Cl, where OAc = acetate anion and L = anilinopyridinate bridging ligand (ap, 2-Meap, 2-Fap). UV/Visible spectroscopy studies reveal that the investigated diruthenium complexes exist in the forms Ru2(OAc)3(L)Cl and [Ru2(OAc)3(L)]+ in solution. The two forms are observed as a split band in the 500 – 700 nm visible region. A collapse of one band is seen upon reaction of the complexes with excess halide (Cl-, Br-) indicating an equilibrium shift towards the neutral species in solution, whereas a reaction with AgBF4 precipitates the chloride as the AgCl salt, leaving only the cationic species in solution. Electrochemical characterization of the mixed-ligand diruthenium complexes conclusively reveals a stable Ru25+ oxidation state in all three complexes. Upon an applied potential in a non-coordinating solvent, each complex undergoes a reversible one-electron oxidation and reduction process accessing the Ru26+, and Ru24+ oxidation states respectively. The treatment of human breast adenocarcinoma MCF-7 cells with these water-soluble complexes results in a less than 50 % cell survival. This demonstrates significance of solubility in the development of metallodrugs for cancer treatment. / XL2018

The coordination chemistry of a structurally rigid phosphine–thioether–borane ligand, TXPB (TXPB = 2,7-di-tert-butyl-5-diphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene), as well as the Group 13 Lewis acid-appended analogues of 1,1'-bis(phosphino)ferrocene, FcPPB (FcPPB = [Fe(η5-C5H4PPh2){η5-C5H4PtBu(C6H4BPh2-o)}]) and FcPPAl (FcPPAl = [Fe(η5-C5H4PPh2){η5-C5H4PtBu(C6H4AlMe2-o)}]) has been explored with a range of transition metal pre-cursors. Previously reported [Rh(μ-Cl)(CO)(TXPB)] (1) reacted with Me3SiBr, Me3SiI, [NMe4]F, Tl[PF6] and NaBH4 to provide [Rh(μ-Br)(CO)(TXPB)] (2), [RhI(CO)(TXPB)] (3), [Rh(CO)(TXPB-F)] {(4); TXPB-F = {5-(2,7-di-tert-butyl-4-diphenylphosphino-9,9-dimethylthioxanthenyl)}diphenylfluoroborate]}, [Rh(CO)(TXPB)][PF6] (5) and [Rh(μ-H)(CO)(TXPB)] (6), respectively; the rhodium–borane and rhodium–co-ligand–borane coordination modes within these complexes are dependant on the co-ligand bound to rhodium (co-ligand = Cl, Br, I, F, H, or none in the case of cationic 5). Additionally, previously reported [(TXPB)Rh(μ-CO)2Fe(CO)Cp] (7) reacted with various isonitriles (CNR; R = C6H4Cl-p, 2,6-Me2-C6H3, nBu) to yield the bridging borataaminocarbyne complexes [(TXPB)Rh(μ-CO)(μ-CNR)Fe(CO)Cp] (8–10). The borane-free analogue of (7), [(TXPH)Rh(μ-CO)2Fe(CO)Cp] (11; TXPH = 2,7-di-tert-butyl-4-diphenylphosphino-9,9-dimethylthioxanthene), was synthesized for comparison, and reacted with CNC6H4Cl-p to yield [(TXPH)Rh(CO)(μ-CNC6H4Cl-p)2Fe(CO)Cp] (12), featuring two bridging isonitrile ligands. The TXPB ligand reacted with [PtMe2(cod)] (cod = 1,5-cyclooctadiene), forming [PtMePh(TXPB')] (13; TXPB' = 2,7-di-tert-butyl-5-methylphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene), which exists in equilibrium with zwitterionic [PtMe(TXPB-Me)] (13') in solution. When heated, [PtMePh(TXPB')] (13) was converted to [PtPh2(TXPB'')] (14; TXPB'' = 2,7-di-tert-butyl-5-dimethylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene) as an 86:14 equilibrium mixture with 13. Moreover, [PtMePh(TXPB')] (13) reacted with PPh3 and P(OPh)3 to provide neutral [PtMePh(PR3)(TXPB')] [R = Ph (15), OPh (16)], or with CNXyl to yield zwitterionic [PtMe(CNXyl)2(TXPB-Me)] (17; TXPB-Me = {5-(2,7-di-tert-butyl-4-diphenylphosphino-9,9-dimethylthioxanthenyl)}methyldiphenylborate). To address several limitations with the TXPB ligand, a new borane-containing ambiphilic ligand, FcPPB (26), was prepared in a seven step convergent synthesis from commercially available ferrocene and 1,2-dibromobenzene. The FcPPB ligand reacted with the Group 10 metal pre-cursors [Ni(cod)2], [Pd2(dba)3] (dba = trans,trans-dibenzylideneacetone) and [Pt(nb)3] (nb = norbornene), yielding co-ligand free [M(FcPPB)] complexes [M = Ni (28), Pd (29), Pt (30)] exhibiting κ2PP- and η3BCC-coordination of the FcPPB ligand. Alternatively, a trisphosphine-analogue of FcPPB, FcPPP (FcPPP = [Fe(η5-C5H4PPh2){η5-C5H4PtBu(C6H4PPh2-o)}]) (25), reacted with [Ni(cod)2] and [Pd2(dba)3] to form [{Ni(FcPPP)}2(μ-N2)] (33) and [Pd(η2-dba)(FcPPP)] (34), respectively. Platinum complex 30 reacted with CO, CNXyl and H2, providing [Pt(CO)(FcPPB)] (35), [Pt(CNXyl)(FcPPB)] (36) and [PtH(μ-H)(FcPPB)] (37), in which the borane is no longer η3BCC-coordinated; the arylborane in FcPPB is now engaged in η2BC-, η1B- and bridging Pt–H–B coordination, respectively. Moreover, [Pt(FcPPB)] (30) reacted with PhC2H to provide [Pt(C2Ph)(μ-H)(FcPPB)] (38), which rapidly isomerized to the vinylborane complex, [Pt(FcPPB')] (39; FcPPB' = [Fe(η5-C5H4PPh2)(η5-C5H4PtBu{C6H4BPh(CPh=CHPh-Z)-o})]). The FcPPB ligand also reacted with [Au(PPh3)][GaCl4] to yield [{Au(FcPPB)}2][GaCl4] (40) as a diastereomeric mixture, or with [W(CO)6] and [Ru3(CO)12] under photochemical and thermal conditions, respectively, to yield [W(CO)4(FcPPB*)] (41; FcPPB* = [Fe(η5-C5H4PPh2){η5-C5H3P(tBu)C6H4BPh-o}]) and [Ru3(μ-H)(CO)10(FcPPB**)] (42; FcPPB** = [Fe(η5-C5H4PPh2){η5-C5H3P(tBu)C6H4BPh2-o}]–), respectively. Both [W(CO)4(FcPPB*)] (41) and [Ru3(μ-H)(CO)10(FcPPB**)] (42) are products of intramolecular attack of the borane on the adjacent cyclopentadienyl-ring. Free FcPPB did not undergo any reaction under similar conditions. However, FcPPB reacted with B(C6F5)3 and BF3·OEt2 to yield FcPPB{B(C6F5)3} (43; [Fe(η5-C5H4PPh2{B(C6F5)3}){η5-C5H4PtBu(C6H4BPh2-o)}]) and [FcPPB-Ph][BF4] (44; [Fe(η5-C5H4PPh2){η5-C5H4PtBu(C6H4BPh-o)}]+), respectively; the former is a phosphine–borane adduct, whereas the latter is a bisphosphine-stabilized boronium cation. The coordination chemistry of a dimethylalane-appended analogue of FcPPB, FcPPAl (27), was also investigated; reaction with [Pt(nb)3] provided [Pt(η2-nb)(FcPPAl)] (45), which readily reacted with C2H4, C2Ph2, H2, and CO to provide [Pt(η2-C2H4)(FcPPAl)] (47), [Pt(η2-C2Ph2)(FcPPAl)] (48), [PtH2(FcPPAl)] (49) and [Pt(CO)(FcPPAl)] (50), respectively. Alternatively, heating a benzene solution of [Pt(η2-nb)(FcPPAl)] (45) yielded co-ligand free [{Pt(FcPPAl)}2] (46). All of the isolated platinum-FcPPAl complexes feature κ3PPAl-coordination of the FcPPAl ligand to platinum, and are the first unambiguous examples of η1Al-coordinated alkylalane complexes. / Thesis / Doctor of Philosophy (PhD) / Ambiphilic ligands are defined as ligands which contain both conventional Lewis basic donors and unconventional Lewis acidic moieties, and the focus of this thesis is to expand the transition metal chemistry of Group 13 Lewis acid-containing ambiphilic ligands. This work expands the knowledge base of fundamental coordination and organometallic chemistry by exploring the effects of ambiphilic ligands on the structures, stability and reactivity of the resulting late transition metal complexes. Three different ambiphilic ligand systems have been employed in this research (TXPB, FcPPB and FcPPAl), which vary either by the structural rigidity of the ligand backbone (TXPB = thioxanthene; FcPPB and FcPPAl = ferrocene), the donor groups available to bind to the metal centre (TXPB = phosphine/thioether; FcPPB and FcPPAl = phosphine/phosphine), or the identity of the appended Lewis acid (TXPB and FcPPB = aryldiphenylborane; FcPPAl = aryldimethylalane). These ligands have provided access to a wide variety of metal–Lewis acid and metal–co-ligand–Lewis acid bonding interactions and novel reaction pathways with small molecules, some of which are relevant to the future development of unique cooperative and catalytic reactivity.

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