Routes to sterically demanding organofluorine-containing phosphines are described, and the stereoelectronic properties and chemistry of the resulting new ligands investigated. The synthesis of Cy2P(CF=CF2), 3, has been accomplished. The nucleophilic substitution of Ph2P(CF=CF2) with tBuLi produces the (Z)-isomer, Ph2P(Z-CF=CF(tBu)), 5-(Z), predominantly, which has been shown to be less electron-withdrawing than Ph2P(CF=CF2), and similar in size to 3. The bis-trifluoropropynyl substituted phosphine PhP(tfp)2, 7, has been prepared, and its reaction with tBuLi investigated. This results in the formation of three previously unknown species, the gem¬-difluorocyclopropenyl-containing compound, PhtBuP(dfcp), 8, (Z)-Ph2P(CH=C(t¬Bu)CF3), 9, and PhtBuP(tfp), 10. The nucleophilic substitution occurs preferentially at the phosphorus centre, as shown by the reaction with one equivalent of tBuLi at -60°C, where compounds 9 and 10 are formed. A new route to perfluoroalkyl-containing phosphines has been discovered. The addition of a perfluoroalkyl iodide to Ph2PSiMe3 results in the formation of six new phosphines, and has been shown to be extendable to partially fluorinated systems. The route can also be applied to iPr2PSiMe3, and to the chiral phosphine PhMePSiMe3. Three examples, Ph2PRf (Rf = CF(CF3)2, 15, (sC4F¬9), 18, (cyc-C6F11), 19), have been produced on a preparative scale. The reaction of the bis-trimethylsilyl phenyl phosphine with (CF3)2CFI has been investigated, though it does not result in the production of the bis-perfluoroalkyl-substituted phosphine, instead the previously unknown P-chiral compound, PhP(H)CF(CF3)2, 27 is formed. Mechanistic studies have indicated that Ph2P-PPh2 is the intermediate, and that there is no evidence of a radical mechanism. There is no reaction between Me2(S)P-P(S)Me2 and (CF3)2CFI, though there is when Me2P-P(S)Me2 is used, suggesting that the lone pair of the intermediate diphosphine is necessary for the reaction to proceed. This has resulted in the formation of the new compound, Me2PCF(CF3)2, 28. The chemistry of the perfluoroalkyl-containing phosphines has been investigated; they do not quaternise, but are oxidatively sensitive. The phosphorus(V) selenides of 15, 18, and 19 have been prepared, and based on their 1JPSe coupling constants, the perfluoroalkyl-groups impart a greater electron-withdrawing effect than perfluorovinyl, trifluoropropynyl, or alkoxy fragments. The oxidation of 15 and 18 with XeF2 has also been accomplished, and shown to yield the corresponding F2PPh2Rf compounds. The molybdenum(0) pentacarbonyl complexes of 3, 7, and 15 have been synthesised and perfluoroalkyl-groups have again been shown to be more electron-withdrawing than perfluorovinyl and trifluoropropynyl groups by comparison of v(CO) values. The gold(I) chloride complexes of Ph2PCF3, 15, and 18 and the platinum(II) dichloride complexes of 3 and 15 have been prepared, and the size of these ligands has been estimated from the crystal structures. Compound 18 has been shown to be the largest of these compounds, with a cone angle of 187°.

The terminal ligand in [(Ph₂phen)₂Ru(dpp)RhCl₂(TL)](PF₆)₃ (Ph2phen = 4,7-diphenyl1,10-phenanthroline; dpp = 2,3-bis(2-pyridyl)pyrazine; TL = terminal ligand – a 4,4′-disubstituted-2,2′-bipyridine where the substituent was carbomethoxy (dcmbpy), hydrogen (bpy) or methyl (Me₂bpy)). The electron-withdrawing ability of the substituent was shown to increase the rate of chloride loss upon electrochemical reduction, facilitating catalytic water reduction. The electronic properties of the terminal ligand also impact the photophysical properties of the molecule. The excited state lifetime of the complex with a dcmbpy terminal ligand was 93 ns while the excited state lifetimes of the complexes with a bpy or Me₂bpy terminal ligand were 44 ns and 47 ns, respectively. Ligand substitution was shown to influence the photocatalytic water reduction activity of these complexes with the dcmbpy complex producing approximately twice the amount of hydrogen (62 ± 7 turnovers in 20 h) as the other two complexes. / Master of Science

Electrochemical potentials of a series of anthraquinone derivatives were studied in both aqueous solution and acetonitrile. The long term goal of this work was to find derivatives which could be reduced easily for studies of photoinduced electron transfer in DNA. Our immediate goal was to find the substitution group that gave the least negative redox potential value. Of all derivatives studied, the anthraquinone imides as a class had the least negative redox potentials, in the range of -0.600 to -0.550 V vs. SCE. One of the anthraquinones studied, one derivative (deoxyadenosine conjugated with an ethynyl linker to an anthraquinone with two ester substituents) was also in this range. A study of a series of anthraquinones conjugated with ethynyl and ethanyl linkers showed that the ethynyl linker was more effective than the ethanyl linker in lowering the redox potential of anthraquinone.