Novel approaches towards phosphorous containing macrocycles

The first chapter in this thesis discusses the general trends in group 15 donor ligands, in particularly nitrogen and phosphorus. The major advancements in phosphorus donor macrocyclic chemistry over the past two decades are documented, and the various synthetic strategies are described. The properties of triphosphorus macrocycles and ensuing complexes are discussed, and the aims of this thesis are summarised. In chapter 2, the preparation of 1-trimemylsilylphosphirane, 2.3, from cUoroemylbis(trimemylsilyl)phospriine, 2.1, is discussed. 1-trimemylsilylphosphirane may be converted to the parent phosphirane, 2.4, by methanolysis, and the coordination chemistry of these phosphines to iron(II), manganese(I), cobalt(III) and Cr(0) centres is discussed. The coordination of the parent phosphirane, 2.4, to the harder metal centres Fe(II) and Co(III) yields the bridging phosphifo-phosphhane dimeric complexes, 2.13 and 2.14, respectively. The reaction of phosphiranes with phosphides is also shown to yield 1,2-bis(phosphino)ethane. The manganese(I)-templated assembly of novel N2P 9 ane macrocycles from coordinated cis and trans 1,2-diaminocyclohexane precursors is reported in chapter 3. The efficiency of macrocycle formation is shown to be effected greatly by the different chelate conformations adopted by cis and trans diaminocyclohexane. Thus, the assembly of 9 ane N2P using the trans isomer is more efficient than the cis analogue. The reactivity of (9 ane N2P)Mn(CO)3 towards the decarbonylating agent, 4-methylmorpholine-N-oxide is shown to be selective, with only the carbonyl group trans to the phosphorus being removed. Attempts to liberate the macrocycle from the manganese centre using hydrogen peroxide and bromine result in the recovery of the free macrocycle, however, oxidation of the phosphorus atom is always observed. Chapter 4 reports the synthesis of seven and nine-membered triphosphines with two primary phosphines at each terminus is also reported. The coordination chemistry of these ligands to the d6 centres Fe(II) and Mo(0) is discussed, as is their reactivity with ring-closing agents, vinyl bromide and l-fluoro,2-iodobenzene