Durham E-Theses A spectroscopic study of some halogeno-complexes of tellurium (IV) Gorrell, Ian Barnes How to cite: Gorrell, Ian Barnes (1983) A spectroscopic study of some halogeno-complexes of tellurium (IV), Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/7890/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk A SPECTROSCOPIC STUDY OF SOME HALOGENO- COMPLEXES OF TELLURIUM (IV) by Ian Barnes Gorrell A thesis submitted in part fulfilment of the requirements for the degree of Master of Science in the University of Durham. The copyright of this thesis rests with the author. April 19 8 3 No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. -5. OFC. 1983 TO MY MOTHER and MY FATHER1 S MEMORY' iii ACKNOWLEDGMENTS I wish to express my gratitude towards the late Professor T.C. Waddington for the encouragement and advice he gave during the early stages of this work. I also wish to thank Dr. C.J. Ludman for his considerable help and excellent supervision throughout my stay in his laboratory. Thanks are also due to Dr. R.S. Matthews for discussions on n.m.r. spectroscopy, Dr. A. Royston who designed and constructed the multinuclear n.m.r. facility, Mr. R. Coult and Mrs. M. Cocks for analyses and Mrs. J. Slegrova for recording most of the vibrational spectra. I also thank Mrs. M. Wilson for typing the manuscript. iv ABSTRACT The aim of this work was to prepare and structurally characterise a series of halogenc— complexes of tellurium (IV). The principal technique used in the structural determination was to have been tellurium-125 nuclear magnetic resonance spectroscopy, used in conjunction with the method of pairwise interactions. Unfortunately, although this method has been used elsewhere with great success, the chemical shifts obtained in the present study did not yield any consistent results, and the presence of a pair of electrons, not formally involved in bonding, is presented as a possible cause of this behaviour. Far-infrared and laser Raman spectroscopy were used in a qualitative manner to determine the configurations of the penta- and hexachlorobromo- complexes and the results obtained were found to agree with those predicted by a stereochemical model developed for complexes of tin. Assignments of new species were made, as far as possible, by analogy with published results for the corresponding complexes of selenium (IV) or antimony (V) and, in some cases, different assignments are given for previously reported species of tellurium (IV). Complexes containing iodine were found to give more com- 2_ plicated results but the new species Tel^X^ (X=F,Cl,Br) were prepared and characterised as well as the TeBr^I anion. The attempted preparation of novel fluoro- species generally led to the isolation of the pentafluorotellurate anion, although the TeBr^F ion is reported for the first time. The preparation of the unknown hexafluorotellurate anion was also attempted, and although it could not be isolated, some evidence was obtained for its presence in an excess of starting materials. Finally, the behaviour of tellurium dioxide in anhydrous hydrogen chloride and hydrogen bromide has been studied. In both cases tellurium tetrahalide is formed and, for the chlorine compound, further reaction occurs to yield a chloroxo- species. A possible reaction pathway is proposed. The analagous aqueous systems were also investigated. V CONTENTS Page No. Acknowledgements iii Abstract iv CHAPTER ONE - PREVIOUS STUDIES IN TELLURIUM-12 5 NUCLEAR MAGNETIC RESONANCE (N.M.R.) SPECTROSCOPY 1 CHAPTER TWO - THE HEXAHALOGENOTELLURATES 5 Introduction 5 2.1 The Hexachloro-, Hexabromo-, and Hexaiodotellurates 5 2.1.1 X-Ray Diffraction Studies 5 2.1.2 Nuclear Quadrupole Resonance (N.Q.R.) Spectroscopy 7 2.1.3 Mossbauer Spectroscopy 8 2.1.4 Vibrational Spectroscopy 10 2.1.5 Other Studies 16 2.2 Mixed Hexahalogenotellurates 22 Results and Discussion 2.3 The Hexachloro-, Hexabromo- and Hexaiodotellurates 2 4 2.3.1 Raman Spectra 2 4 2.3.2 Far-Infrared Spectra 25 2.3.3 Tellurium-125 N.M.R. Spectra 27 2.4 Mixed Hexahalogenotellurates 2 8 2.4.1 The Chlorobromotellurates 28 (a) Raman Spectra 2 8 (b) Far-Infrared Spectra 31 (c) Tellurium-125 N.M.R. Spectra 33 (d) Stereochemistry 34 2.4.2 The Chloroiodotellurates 37 (a) Raman Spectra 37 (b) Far-Infrared Spectra 39 (c) Tellurium-125 N.M.R. Spectra 40 vi Page No. 2.4.3 The Bromoiodotellurates 41 (a) Raman Spectra 41 (b) Far-Infrared Spectra 42 (c) Tellurium-125 N.M.R. Spectra 43 2.4.4 The Mixed Fluorotellurates 43 (a) Vibrational Spectra 44 (b) N.M.R. Spectra 45 47 Conclusion Experimental 49 2.5 The Hexachloro-, Hexabromo- and Hexaiodotellurates 49 2.6 Mixed Hexahalogenotellurates 50 CHAPTER THREE - THE HEXAFLUOROTELLURATE ANION 54 Introduction 54 Results and Discussion 56 3.1 Reaction between Me^NF and Me^NTeF^ in Liquid Sulphur Dioxide 56 3.2 Reaction between Bu4NF.nH20 and Bu^NTeF^ in Dichloromethane 57 3.3 Reaction between NaF and NaTeF,- in the Presence .of. 18-Crgwct26__ Ether _ 57 3.4 Reaction between Bu4NF.nH20 and Bu^NTeF,. in the Fused State 58 Conclusion 59 Experimental 59 3.5 Reaction between Me^NF and Me^NTeF,- in Liquid Sulphur Dioxide 59 3.6 Reaction between Bu^NF.n^o and Bu4NTeF,- in Dichloromethane 60 vii Page No. 3.7 Reaction between NaF and NaTeF,. in the Presence of 18-Crown-6-Ether 61 3.8 Reaction between Bu4NF.nH20 and Bu^NTeF,- in the Fused State 61 CHAPTER FOUR - THE PENTAHALOGENOTELLURATES 64 Introduction 64 4.1 The Pentahalogenotellurates not Containing Fluorine 64 4.2 The Pentafluorotellurates 69 Results and Discussion 71 4.3 The Chlorobromotellurates 71 4.3.1 Raman Spectra 71 4.3.2 Far-Infrared Spectra 76 4.3.3 Tellurium-125 N.M.R. Spectra 78 4.4 The Chloroiodo-, Bromoiodo- and Pentaiodotellurates 79 4.5 The Fluorotellurates 81 4.5.1 Vibrational Spectra 82 4.5.2 Tellurium-125 N.M.R. Spectra 84 Conclusion .37. Experimental 87 CHAPTER FIVE - REACTIONS OF TELLURIUM DIOXIDE WITH AQUEOUS AND ANHYDROUS HYDROGEN CHLORIDE AND HYDROGEN BROMIDE 91 Introduction 91 5.1 Reaction of Tellurium Dioxide with Anhydrous Hydrogen Chloride 91 5.2 Reaction of Tellurium Dioxide with Aqueous Hydrogen Chloride 92 5.3 Reaction of Tellurium Dioxide with Anhydrous Hydrogen Bromide 94 5.4 Reaction of Tellurium Dioxide with Aqueous Hydrogen Bromide 94 viii Page No. Results and Discussion 95 : 5.5 Reaction of Tellurium Dioxide with Anhydrous Hydrogen Chloride 95 5.6 Reaction of Tellurium Dioxide with Aqueous Hydrogen Chloride 100 ; 5.7 Reaction of Tellurium Dioxide with Anhydrous Hydrogen Bromide 102 ; 5.8 Reaction of Tellurium Dioxide with Aqueous Hydrogen Bromide 103 : Conclusion 104 Experimental 104 5.9 Reaction of Tellurium Dioxide with Anhydrous Hydrogen Halide 104 5.10 Reaction of Tellurium Dioxide with Aqueous Hydrogen Halide 105 CHAPTER SIX - EXPERIMENTAL METHODS " 106 6.1 The Dry Box 106 6.2 The Vacuum Line 106 6.3 X-Ray Power Diffraction Photography 109 6.4 Fluorine-19 N.M.R. Spectroscopy 109 6.5 "The" Tellurium-12 5 N.M.R." "Spectrometer " 110 6.6 Vibrational Spectroscopy 110 6.7 Preparation of Starting Materials 112 6.7.1 Tetrabutylammonium Fluoride 112 6.7.2 The Pentafluorotellurates 113 6.7.3 Tellurium Tetrafluoride 114 6.7.4 Tellurium Dichloridedibromide 114 6.7.5 Tellurium Dibromidediiod-ide 115 ix Page No. 6.8 Analyses 116 6.9 Solvents 117 6.10 Purification of Hydrogen Chloride and Hydrogen Bromide 117 APPENDIX 119 REFERENCES 120 1 CHAPTER ONE PREVIOUS STUDIES IN TELLURIUM-12 5 NUCLEAR MAGNETIC RESONANCE (N.M.R.) SPECTROSCOPY Tellurium-125 (1=^; natural abundance 7.03%) has a re- _3 ceptivity of only 2.21 x 10 , relative to that of the proton, and this has delayed the direct observation of its chemical shift in systems of interest to the chemist until the advent of Fourier transform spectrometers, although measurements had been made on some solid state systems."1" Prior to this, double resonance techniques were used in which the tellurium nucleus in question was coupled to a much more n.m.r.-receptive nucleus, usually a proton. If, when observing the proton spectrum, the sample is simultaneously irradiated at the tellurium resonance 125 1 frequency, then the Te- H coupling will be destroyed. A knowledge of the exact frequency that gives optimum decoupling leads to the tellurium chemical shift. The results, obtained using this technique, for some organotellurium compounds, have been reviewed.^ The first high resolution Fourier transform study re• ported the effect of differing substituents on the chemical shifts of 2-substituted tellurophenes, and since then a range of organic tellurium compounds has been investigated including 4 benzotellurophene (Fig.1.1) and its derivatives, tellurol 5 esters (Fig.1.2), 1,3-dihydrobenzotellurophene (Fig.1.3) and its dihalogeno- oxidation products,^ cyclic and acyclic phenyl- tellurium compounds,^^ di-2-tellurienylketone^^ (Fig.1.4) g and some trifluoromethyltellurium compounds.