The synthesis and characterisation of macrocrylic ligands with N, O and S donor atoms and related transmission metal complexes of these ligands




Ingham, Alison Mary

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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[]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.



Ligands, Macrocrylic compounds