The Preparation of Organosulfur Derived Electron Transfer Salts
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The Preparation of Organosulfur Derived Electron Transfer Salts Andrew C. Brooks A thesis submitted in partial fulfilment of the Requirements of Nottingham Trent University For the degree of Doctor of Philosophy July 2009 School of Science and Technology Davy-Faraday Research Laboratory Nottingham Trent University Kathleen Lonsdale Building Clifton Lane University College London Nottingham Gower Street NG11 8NS London WC1E 6BT This work is the intellectual property of the author, and may also be owned by the research sponsor(s) and/ or Nottingham Trent University. You may copy up to 5 % of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the first instance to the author. Abstract The concept of this thesis is to effect greater control over the crystalline state of radical cation salts in order to enhance electron transport, and to allow for the incorporation of additional functionality such as optical activity or magnetism. The salts formed are based on the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) framework, and are produced using the technique of electrocrystallisation. In attempts to control the crystal packing arrangements observed, a number of approaches have been explored including the incorporation of chirality, hydrogen bonding interactions and coordinate bonding interactions. These properties have been installed on the electron donor molecule and/ or the charge stabilising anion component. This thesis presents a novel radical cation salt that has been prepared from ET and the sulfamate anion, and which exhibits ordered channels of hydrogen bonded anions and water molecules extending in one crystallographic dimension. This research has also discovered an unusual chiral crystallographic packing observed in a novel semiconducting radical cation salt formed from ET and the bromide anion. Also presented are the synthesis of a family of metal-binding electron donors and the first radical cation salts formed from these, including a perrhenate salt which is both N- protonated and oxidised, giving an overall charge of +2 on the electron donor molecule. A group of novel aldehyde-functionalised donors are discussed, one of which could lead to a Little-type superconductor, and the syntheses towards a bis(donor) molecule containing a spiro centre, and separately a porphyrin appended electron donor are presented. Acknowledgements First and foremost I have to thank Professor John D. Wallis and Professor Peter Day FRS, for providing me with the opportunity to undertake research into this most fascinating field of interdisciplinary science. Your encouragement, enthusiasm and advice have inspired me throughout the past few years. Thank you also to Dr Lee Martin for your help with measurements and training, and for your friendship over the past couple of years, and to Dr Gary Hix for your advice and support. I also want to thank Dr Rob Smith, Dr Qiang Wang, Dr Songjie Yang and Dr Sara Krivikas for their advice and friendship over the past few years. Thank you to Dr Ian Watts (UCL) for assistance with conductivity measurements, and Dr Steve Firth (UCL) for the use of the Raman microscope. A big thank you to Dr David Chambers-Asman, Mr Mark Sladen, Mrs Marilyn Johnson, Mr Mark Cosgrove and Ms Barbara Stevenson for assistance with training on equipment and providing valuable technical support. Thank you to Gary Baker and Muriel Funck for providing the entertainment in the lab, the numerous food challenges, and the endless river of tea and coffee. Thank you to Vicky Mundell, Daniel Paul-Guest and Laura Neeves for the laughs, stories and experiences shared over the past few years, and to the many other students who have made the labs enjoyable places in which to conduct research. Thank you to Dr Bob Baker, Dr Gareth Cave, Dr Chris Garner, Dr Patrick Huddleston, Dr Michael Stockenhuber, Professor Richard Joyner, Professor Vernon Richardson and Professor Carole Perry for their advice during my studies. A special thank you to Mr Jim Bottrill, who introduced Nottingham Trent University to me, and whose encouragement and positive outlook always helped when the situation seemed grim. Thanks to John Spray for preparing the electrocrystallisation cells and electrodes, Brian O’Neill and Peter Moore for preparing the constant current sources, the EPSRC National X-ray service at Southampton for the X-ray data sets, the EPSRC National Mass Spectrometry Service for the mass spectrometry data, and Mr Stephen Boyer (London Metropolitan University) for providing the elemental analysis data. A special thank you to Neil Bowley whose friendship, support, and singing has constantly encouraged me to succeed over the last eight years, amused me, and ruined my hearing. Thanks mate… Many thanks go to Luke Headland and Laura Vahter for being great friends, and helping me to leave work at work when I needed to relax. Lastly, my biggest thanks go to my fiancée Laura, for supporting me, and to Mum, Dad, Elaine, Aivars, Matthew, Jessica, Andrew, Katherine, Richard, Annette, Antony, Danielle, Winston and every other member of the family who have in one way or another helped me achieve this thesis. Without all of your support, this couldn’t have been done. This thesis is dedicated to Laura and my family, without whom this thesis could never have been completed . Contents 1 Introduction 1 1.1 Types of conductivity 2 1.1.1 Band theory 2 1.1.2 Insulator 3 1.1.3 Semiconductor 4 1.1.4 Metal 6 1.1.5 Superconductor 7 1.2 Superconductivity 7 1.3 B. C. S. theory 8 1.4 Superconducting metal alloys 10 1.5 Conductivity in non-metallic materials 12 1.6 Non-metallic superconductors 13 1.7 Tetrathiafulvalene 17 1.8 Bis(ethylenedithio)tetrathiafulvalene 20 1.9 First organosulfur superconductor 25 1.10 First ambient pressure organosulfur superconductor 26 1.10.1 α- Phase packing of ET 29 1.10.2 β- Phase packing of ET 30 1.10.3 γ- Phase packing of ET 31 1.10.4 δ- Phase packing of ET 32 1.10.5 ε- Phase packing of ET 32 1.10.6 κ- Phase packing of ET 32 1.10.7 Unusual ligating behaviour of ET 36 1.10.8 ET halide salts 38 1.11 Temperature effects on the crystal conductivity 40 1.12 Functionalisation of the ET donor 41 1.13 Bis(vinylenedithio)tetrathiafulvalene 44 1.14 Techniques for the characterisation of electron-transfer salts 45 1.14.1 Raman spectroscopy 45 1.14.2 Elemental analysis 47 1.14.3 Thermal gravimetric analysis 48 1.14.4 Infrared spectroscopy 48 1.14.5 Single crystal X-ray crystallography 49 1.14.6 EPR spectroscopy 50 1.14.7 X-ray electron microprobe analysis 51 1.14.8 Superconducting quantum interference device 51 1.14.9 RF measurements 52 1.15 The magnetic properties of electron-transfer salts 52 1.15.1 Types of magnetism 54 1.15.2 Magnetic susceptibility 56 1.16 Electrocrystallisation 58 1.17 Other types of conducting materials 61 1.17.1 Polymers 61 1.17.2 Inorganic and ceramic superconductors 62 1.18 Applications of electron-transfer materials 64 1.19 References 66 2 Chiral organosulfur-derived electron donors 74 2.1 Introduction 75 2.2 Results and discussion 80 2.3 Materials made by electrocrystallisation 90 2.4 Experimental 95 2.5 Electrocrystallisation experimental 105 2.6 References 111 3 Metal-binding electron donors 113 3.1 Introduction 114 3.2 Results and discussion 119 3.3 Materials made by chemical oxidation or electrocrystallisation 137 3.3.1 (70)(CuCl 2)3(CH 3CN) 0.75 (H 2O) 1.5 137 3.3.2 (70)x(CoCl 4)y 138 + 3.3.3 (70-H) (ReO 4)2.0.5(CH 2Cl 2) 139 3.3.4 Experimental 144 3.3.5 Electrocrystallisation experimental section 156 3.4 References 158 4 Novel radical cation salts formed from ET 159 4.1 Synthesis of new radical cation salts of ET with the sulfamate anion 160 4.1.1 Introduction 160 4.1.2 Results and discussion 163 4.1.3 (ET) 3(H 2NSO 3)2.2H 2O 163 4.1.4 Electron transfer properties of (ET) 3(H 2NSO 3)2.2H 2O 173 4.1.5 Charge state of the donor species 175 4.1.6 Experimental 176 4.2 Electrochemical synthesis of a new solvated structure of ET chromium hexathiocyanate, (ET) 4[Cr(NCS) 6].C 6H5NO 2 180 4.2.1 Introduction 180 4.2.2 Results and discussion 185 4.2.3 Experimental 199 4.2.4 Electrocrystallisation experimental 202 4.3 Chiral packing of achiral components 203 4.3.1 Introduction 203 4.3.2 Results and discussion 204 4.3.3 Experimental 219 4.3.4 Electrocrystallisation experimental 221 4.4 (ET) 3(CoCl 4)2 223 4.4.1 Introduction 223 4.4.2 Results and discussion 223 4.4.3 Experimental 226 4.5 References 228 5 Chiral metal anion complexes 231 5.1 Introduction 232 5.2 Results and discussion 233 5.3 Experimental 237 5.4 Electrocrystallisation experiments 244 5.5 References 247 6 Aldehyde functionalised organosulfur electron donors 248 6.1 Introduction 249 6.2 Results and discussion 252 6.3 Experimental 269 6.4 References 278 7 A Porphyrin based electron donor 279 7.1 Introduction 280 7.2 Results and discussion 281 7.3 Experimental 284 7.4 References 289 8 A spiro organosulfur compound 290 8.1 Introduction 291 8.2 Results and discussion 292 8.3 Experimental 294 8.4 References 296 9 Recommendations for further work 297 Appendix 1 GC-MS method 300 CD-ROM X-ray crystal structure .cif files Table of Figures Figure 1 : Possible band structures of a solid.