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Studies on Macrocyclic Complexes

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Studies on Macrocyclic Complexes Studies on Macrocyclic Complexes by Christian Radek Thesis presented for the Degree of Doctor of Philosophy The University of Edinburgh Der Herbst des Einsamen Der dunkle Herbst kehrt ein voll Frucht und Fülle, Vergilbter Glanz von schOnen Sommertagen. Ein reines Blau tritt aus verfallener HulIe; Der Flug der Vogel tOnt von alten Sagen. Gekeltert ist der Wein, die milde Stille Erfullt von leiser Antwort dunkler Fragen. Und hier und dort ein Kreuz auf odem Hugel; Im roten Wald verliert sich eine Herde. Die Wolke wandert ubern Weiherspiegel, Es ruht des Landmanns ruhige Geberde. Sehr leise rührt des A bends blauer Flu gel Ein Dach von durrem Stroh, die schwarze Erde. Bald nisten Sterne in des Müden Brauen; In kühlen Stuben kehrt ein still Bescheiden Und Engel treten leise aus den blauen Augen der Liebenden, die sanfter leiden. Es rauscht das Rohr; anfallt ein knOchern Grauen, Wenn schwarz der Tau tropft von den kahien Weiden. Georg Trakl (1887 - 1914) The work described in this thesis is dedicated to the memory of Uli and my grandparents without whom this work would not have been possible. ACKNOWLEDGEMENTS I would like to thank Martin SchrOder for giving me the opportunity to undertake the work presented in this thesis in his research group. I am indebted to him for his support, encouragement, enthusiasm and friendship throughout the course of this work. My thanks also go to Sandy Blake, Bob Gould and Simon Parsons for their invaluable help with the intricacies of X-ray crystallography. My thanks include Steve Harris who did his fourth year project with Sandy Blake for solving and refining the structure of [21]aneS205. Further thanks go to John Millar, Heather Grant, David Reed and Wesley Kerr for recording NMR-spectra, Alan Taylor and Elizabeth Stevenson for running FAB- and El-mass spectra, Lorna Eades for performing microanalytical measurements and Jeremy Rawson for running ESR spectra. My thanks also include Dr.J.G.Fitton (Department of Geology) for running X-ray fluorescence spectra. I would like to acknowledge the support, encouragement, advice and friendship of a range of people over the last four years namely Prof. Brian Johnson, Prof. Karl Wieghardt, Lisa Martin, Helen Baxter, Bob Baxter and Thomas Weyhermuller, the members of Prof. SchrOder's research group and the inorganic section in particular Andy Atkins, Phil Bailey, Armando Marin-Beccera, Daniel Black, Rhona Crofts, Jon Danks, Therese Donlevy, Paul Dyson, Ian Fallis, Rachel Grimditch, Broer de Groot, Malcolm Halcrow, Vito Lippolis, Cohn Pulham, Gill Reid, Heiko Richtzenhain, Steve Ross, Otto Smékal and Martin Sullivan. For essential financial support I would like to thank first of all my grandparents. Additionally I would like to thank my uncle Uli, my mother, Prof. B.FG.Johnson and Martin SchrOder. My thanks also go to the British Crystallographic Association (BCA) for a grant which enabled me to participate at the Intensive Course in X-Ray Crystallography, The University of Edinburgh, Senatus Postgraduate Studies Committee for a financial contribution to my studies, and The University of Edinburgh Student Accommodation Service for offering me the position of a senior resident in a student house over a period of two years. I would also like to express my gratitude for the use of laboratory facilities and computer resources at The University of Edinburgh and the use of online database facilities of the S.E.R.C. at Daresbury. ABSTRACT The work described in this thesis deals with the co-ordination chemistry of the macrocyclic ligands: [9]aneS3 ................(1,4,7-trithiacyclononane) [12]aneS4 ............... (1,4,7,1 0-tetrathiacyclododecane) [14]aneS4 ............... (1,5,8, 1 2-tetrathiacyclotetradecane) [1 6]aneS4 ............... (1,5,9, 1 3-tetrathiahexadecane) [1 5]aneS ............... (1,4,7,10, 1 3-pentathiacyclopentadecane) [18]aneS6 ............... (1,4,7,10,13, 16-hexathiacyclooctadecane) [24]aneS8 ...............(1,4,7,10,13,16,19,22-octathiacyclotetraeicosane) [15 ]aneS2O3 ...........(1 ,4,7-trioxa- 10,1 3-dithiacyclopentadecane) [18]aneS2O4 ........... (1,4,7,1 0-tetraoxa- 13,1 6-dith iacyclooctadecane) benzo[ 1 8]aneS2O4 .... (4,7,10,1 3-tetraoxa- 1,1 6-dithia[ 161 -o-cyclophane) [2 1]aneS2O5 ........... (1,4,7,10, 13-pentaoxa- 16,1 9-dithiacycloheneicosane) [1 8]aneS3O3 ...........(1, 4,7-trioxa- 10,13,1 6-trithiacyclooctadecane) [20]aneS303 ...........(1,4,7-trioxa- 10,14,1 8-trithiacycloeicosane) The synthesis of [18]aneS204, [18]aneS303 benzo[18]aneS204 and [20]aneS303, the single crystal X-ray structures of [15]aneS203, [18]aneS204 and ([21]aneS205)1.1/2 H20, and molecular mechanics calculations on [18]aneS204 are described. ([21]aneS205)11/2 H20 is the first example of a neutral molecule binding to a mixed 0/S-donor ionophore with H-bonding to the hard polyether binding site. Studies of Ru(II) and Pd(II) complexes with these ligands were initiate in order to establish the fundamental co-ordination chemistry between mixed 0/S- donor ionophores and to establish the potential of these complexes to be used in the development of a metal mixed 0/S-donor macrocyclic host guest chemistry. [RuC12PPh3([15]aneS203)] and [RuCl(PPh3)([15]aneS203)2]PF6 were prepared by the reaction of [15]aneS203 with [RuC12(PPh3)3]. The role of [RuCl2PPh3([15]aneS203)] as a potential intermediate in the formation of the two isomers of [RuCl(PPh3)([15]aneS203)2]PF6 is discussed. The reaction of [18]aneS204 with [RuC12(PPh3)3] afforded [RuCl(PPh3)(118janeS204)2]PF6. [Ru([18]aneS2O4)3](PF6)2 was prepared by the reaction of [18]aneS204 and 'RuC13xH20' in the presence of potassium oxalate as a reducing agent. [Ru2C14(116-C6H6)2] and Reactions of [18]aneS204 with organometallic species [RuC1(PPh3)2(115-05H5)] afforded the 6-C6H6)(11 [RuCI(r16-C6H6)(1 1 8]aneS2O4)]PF6, [RUCI(11 8IaneS2O4)]BPh4 and [Ru(T15C5H5)(pph3)([181aneS204)]PF6. The single crystal X-ray structures of all compounds prepared are described. In all cases the macrocyclic ligands co-ordinate to the Ru(II) ion in an exo bidentate manner. [PdCl2([18IafleS204)1 and [Pd([18]afleS204)21(PF6)2 were prepared by reaction -of PdC12 with [18]aneS204. The reaction of [18]aneS303 and afforded and [20]aneS303 with PdCl2 [Pd([ 1 8]aneS3O3)2}(PF6)2. [PdC]([20]aneS303)]BPh4, the single crystal X-ray structures of which we describe. The Pd(II) ion adopts in the first three cases an exo co-ordination mode whereas in case of [PdCl([20]aneS303)IBPh4 endo co-ordination is present. Mixed 0/S-donor macrocyclic complexes containing exo co-ordinated Ru(1I) and Pd(II) ions are unsuitable candidates as hosts for other cations or neutral molecules due to steric and conformational reasons. [20]aneS303 has been identified as a potential candidate for further investigation and development. The complexes [Tl([ 15]aneS2O3)2]PF6, [Tl([ 1 8]aneS2O4)]PF6 and [TI(benzo[18]aneS204)]PF6 were prepared by the reaction of TIPF6 with [15]aneS2O3, [18]aneS2O4 and benzo[18]aneS204 respectively. The characterisation of these compounds is described. Similarities between spectroscopic results for these compounds compared with Ag(I) complexes (see below) suggest in-cavity co-ordination of the TI(I) ions within the macrocycle. Reactions of [1 8]aneS2O4 with AgNO3/NH4PF6 and AgClO4 afforded the two complexes [Ag([ 1 8laneS2O4)21 (PF6)2 and [Ag4(1 1 8]aneS2O4)4] (dO4)4. The single crystal X-ray structures of the products show Ag-atoms co-ordinated within the macrocyclic cavities with a range of Ag-S and Ag-U bonds. The structures of both compounds exhibit a series of thioether bridges between Ag(I) ions and [Ag4(118]aneSO4)41(Cl04)4 shows an unusual cyclic 4-membered Ag2S2 moiety. NMR studies, however, suggest the presence of mononuclear species in solution. The features found in the single crystal X-ray structures are therefore confined to the solid state and the degree of oligomerisation is dependent on the nature of the counterion. - vii - [Ag([18]aneS)]I7 and [Ag([18]aneS)1I3 were prepared by the reaction of [Ag([18]aneS)IBF4 with 12 in MeCN. The single crystal X-ray structure of [Ag([18]afleS)II7 shows a novel 3-dimensional polymeric polyiodide (176 which forms a cubane structure around the cation whereas [Ag([18]aneS)II3 shows a sheet-like structure. No AgI precipitation was observed in either reaction underlining the inertness of the [Ag([18]afleS)]+ cation under these conditions. The ability of cationic metal macrocyclic complexes to not only stabilise but to template extended anionic species is discussed. The reaction of 12 with S-donor macrocycles in CH2Cl2 afforded 12 thioether charge transfer complexes. Solid state studies on ([9]aneS3)2(12)4, ([12]aneS4)12, ([14]aneS4)12, ([1 6]aneS4)12 ([1 6]aneS4)(12)4, ([15]aneS5)(12)5, ([1 8]aneS6)12, ([18]aneS6)(12)4, ([24]aneS8)12 and ([24]aneS8)(12)4 are described. These structures can be broadly divided into two groups. 12 rich compounds show a columnar stacking motif of macrocyclic ligands, and 12 deficient compounds adopting a layered 1-dimensional chain structures with 12 molecules bridging between different macrocycles. Solution studies on [9]aneS3 and [18]aneS6 are described. CHAPTER I An introduction into the chemistry of macrocyclic compounds is given dealing with a brief historical outline of the key developments. Features special to macrocyclic co-ordination chemistry such as thermodynamic stability and kinetic inertness are emphasised and discussed. Other topics included in this introduction deal with the role of transition metal ions in biological systems, macrocyclic metal complexes in catalysis and applications for macrocyclic Ilgancis in particutar covering chemical sensing, solvent extraction and medical applications such as contrast agents for imaging purposes and the development of anti-cancer drugs.
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