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Synthesis of Coordination Complexes Using Mixed Donor Chalcogenoether Macrocycles to Investigate Hard/Soft Metal to Ligand Interactions

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Synthesis of Coordination Complexes Using Mixed Donor Chalcogenoether Macrocycles to Investigate Hard/Soft Metal to Ligand Interactions University of Southampton Research Repository ePrints Soton Copyright © and Moral Rights for this thesis are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder/s. The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given e.g. AUTHOR (year of submission) "Full thesis title", University of Southampton, name of the University School or Department, PhD Thesis, pagination http://eprints.soton.ac.uk UNIVERSITY OF SOUTHAMPTON FACULTY OF NATURAL AND ENVIRONMENTAL SCIENCES Chemistry SYNTHESIS OF COORDINATION COMPLEXES USING MIXED DONOR CHALCOGENOETHER MACROCYCLES TO INVESTIGATE HARD/SOFT METAL TO LIGAND INTERACTIONS by Paolo A. Farina Thesis for the degree of Doctor of Philosophy NOVEMBER 2013 UNIVERSITY OF SOUTHAMPTON ABSTRACT FACULTY OF NATURAL AND ENVIRONMENTAL SCIENCES Chemistry Thesis for the degree of Doctor of Philosophy SYNTHESIS OF COORDINATION COMPLEXES USING MIXED DONOR CHALCOGENOETHER MACROCYCLES TO INVESTIGATE HARD/SOFT METAL TO LIGAND INTERACTIONS Paolo Alberto Farina Improvements to the synthesis of Group 16 mixed donor macrocycles are reported. The mixed donor chalcogenoether macrocycles [15]aneO S , 3 2 [18]aneO S and [18]aneO E (E= S, Se and Te) can coordinate a range of both 2 4 4 2 soft and hard Lewis acids. Complexes investigating hard Lewis acids focussed on Ca(II), Sr(II), Sc(III) and Y(III) halides. The Group 2 metals are coordinated to all the donors in the macrocycle, importantly the metal centres showed an affinity for the softer donor (S, Se) as well as the harder donor (O). This interaction was maintained even after trace ingress of water. The lattice energies of the starting metal precursors were important in accessing the coordination chemistry of Ca(II) and Sr(II), CaI and SrI both gave products of 2 2 the type [MI (macrocycle)]. Similarly ScI was reacted with the macrocyclic 2 3 ligands to give ionic solids [ScI (macrocycle)][I]. The analogous Y(III) and Sc(III) 2 chlorides were also synthesised by using the halide abstractor FeCl and 3 [ScCl (THF) ] and [YCl (THF) ][YCl (THF) ] to give complexes of the type 3 3 2 5 4 2 [MCl (macrocycle)][FeCl ]. The macrocycles bind hexadentate (pentadentate in 2 4 case of [15]aneO S ) to the Group 3 cations. Softer and borderline Lewis acids 3 2 Sn(XF ) and Pb(XF ) (X=B, P; n= 4, 6 respectively) form complexes with the n 2 n 2 Group 16 donor macrocycles. The coordination compounds exhibit a range of unusual coordination modes for the weakly coordinating fluoroanions ([BF ]- μ2, 4 2 1 - 3 2 κ and κ ; [PF ] κ and κ ). Pb(II) and Sn(II) were shown to encourage the 6 hydrolysis of the [PF ]- anion and the decomposition of [18]aneO Te . Sn(II) also 6 4 2 cleaved the other [18]aneO E (E= S, Se) macrocycles, the complex 4 2 [Sn([18]aneO S )(HO(CH ) OH)][BF ] is the first structural evidence for metal 4 2 2 2 4 2 mediated ring opening of a saturated oxa-thia macrocycle. A series of coordination complexes of Sb(III), a soft Lewis acid, halides were investigated. Structural comparisons between the analogous fluoro-, chloro- and iodo- antimony(III) complexes showed the corresponding halide greatly influenced the Lewis behaviour of Sb(III). X-ray crystallography, 1H (and where appropriate 19F, 31P, 45Sc, 77Se and 125Te) NMR spectroscopy, elemental analysis, conductivity measurements and IR spectroscopy were used to characterise the complexes in this study. Contents ABSTRACT ................................................................................................................................ i Contents ................................................................................................................................... i List of tables ......................................................................................................................... v List of figures ......................................................................................................................ix DECLARATION OF AUTHORSHIP ............................................................................. xv Acknowledgements ...................................................................................................... xvii Definitions and Abbreviations ............................................................................... xix 1. Introduction ................................................................................................................ 1 1.1 Macrocycles ........................................................................................ 1 1.2 Heterocrown and Crown ether coordination chemistry ........................ 5 1.3 Characterisation Techniques ............................................................. 13 1.3.1 Single Crystal X-ray crystallography ............................................ 13 1.3.2 NMR spectroscopy ...................................................................... 14 1.3.3 IR Spectroscopy .......................................................................... 17 1.3.4 Mass spectrometry ..................................................................... 18 1.3.5 Conductivity studies ................................................................... 18 1.4 Aims ................................................................................................. 21 1.5 References ........................................................................................ 23 2. Mixed Donor Chalcogenoether Macrocycle Synthesis .................... 27 2.1 Introduction ..................................................................................... 27 2.1.1 Mixed Donor Group 16 Macrocycles ........................................... 31 2.1.2 Ligand preorganisation .............................................................. 34 2.2 Results and Discussion ..................................................................... 37 2.3 Conclusions ...................................................................................... 43 2.4 Experimental .................................................................................... 45 2.5 Structural Data ................................................................................. 51 2.6 References ........................................................................................ 53 i 3. Mixed Chalcogenoether Donor Macrocyclic Complexes of Divalent Calcium and Strontium ............................................................................ 55 3.1 Introduction ...................................................................................... 55 3.2 Results and Discussion ..................................................................... 59 3.2.1 Ca(II) coordination chemistry ...................................................... 59 3.2.2 Sr(II) coordination chemistry ....................................................... 75 3.3 Conclusions ...................................................................................... 83 3.4 Experimental .................................................................................... 85 3.5 Structural Data .................................................................................. 91 3.6 References ........................................................................................ 95 4. Mixed Chalcogenoether Donor Macrocyclic Complexes of Trivalent Scandium and Yttrium ............................................................................ 97 4.1 Introduction ...................................................................................... 97 4.2 Results and Discussion ................................................................... 101 4.2.1 Sc(III) coordination chemistry .................................................... 101 4.2.1.1 45Sc NMR spectroscopic studies .......................................... 111 4.2.1.2 [ScCl (MeCN) ] .................................................................... 113 3 3 4.2.2 Y(III) coordination complexes .................................................... 114 4.3 Conclusions .................................................................................... 119 4.4 Experimental .................................................................................. 121 4.5 Structural Data ................................................................................ 127 4.6 References ...................................................................................... 129 5. Mixed Donor Chalcogenoether Macrocyclic Complexes of Lead(II)................................................................................................................................. 133 5.1 Introduction .................................................................................... 133 5.1.1 Non-/Weakly-Coordinating Fluoroanions ............................. 138 5.2 Results and Discussion ................................................................... 139 5.2.1 Pb(II) precursors ....................................................................... 139 5.2.2 Pb(II) complexes with 15-membered macrocycles ..................... 140 5.2.3 Pb(BF ) complexes with 18-membered
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