The Synthesis and Characterisation of Macrocyclic Ligands with N, O and S Donor Atoms, and related Transition Metal Complexes of these Ligands. by Alison Mary Ingham B.Sc. (Hons.), University of the Witwatersrand, 1991 A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY in the Department of Chemistry We accept this dissertation as conforming to the required standard Dr. A. McAuley, Supervisor (Dgpartment of Chemistry) Dr. K.R. Dix (Department of Chemistry) Dr. D.J. Berg, Departmental Meriroer (Deparjrf^t of Chemistry) Dr. G.A. Beer, Outside Member (Department of Physics) Dr. C Orvig, External Examineraminer (Department ^ ep of Chemistry, University of British Columbia) © Alison Mary Ingham, 1996 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without the permission of the author. u ABSTRACT Supervisor: Dr. Alexander McAuley The ligand l-oxa-4,8-diazacyclodecane ([lOjaneNjO) was synthesised, along with the Cu“, Ni“, Pd“ and Co“ complexes, fiw-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 [Cu([1 0 ]aneNiO)J(ClO«)2 *(H 2 P) was determined, as is described. The copper(II), nickel(II) and paHadium(n) complexes have been characterised by FAB MS, electronic spectroscopy, elemental analysis and where possible by NMR and EPR spectroscopy. The nickel(II) and copper(n) 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 withiiL The synthesis of the novel tricyclic ligand, 7,16-dioxa-1,4,10,13- tetraazatricyclo[11.5.3.3]octadecane (tricyclo[ 10-14-lOlN^O^) is described. The Cu“ conplex has been synthesised and characterised. The complex gives an unusually stable Cu' complex compared to complexes where a similar donor set is present A novel template synthesis was utilised to synthesise the bicyclic ligand l,2-i>fr(l-oxa-5,8- diazacyclodecanyl)ethane ([lOjaneNzO earmuff). This synthesis involved reaction of lU 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) conçlex synthesised during this reaction has been characterised, and the redox reactions have been examined. The synthesis of 17-oxa-I,4,8,ll-tetraazabicyclo[6.6.5]tetradecane (bicycloElZ-lZjN^O) is reported. Copper(H) and nickeI(II) complexes of this ligand have been synthesised and characterised. The chloride ion substitution reaction of [Ni(bicyclo[ 1 2 - 1 2 ]N 4 0 )(OH2 )]^ 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 170±10M'*. The cobaltÇHI) h/j-ligand complex of the previously synthesised ligand, 8-aza-l,5- dithiacyclodecane ([lOjaneS^N) was synthesised. Under the conditions used, two isomers were formed - a facially coordinate his-ligand complex where the equatorial plane is defined by two sulfur and two nitrogen donors, and a more symmetrical isonxr where all four sulfur donors are coordinated equatorially. Isomensation of the unsymmetrical isomer to the symmetrical isomer occurs in solution. The Co“ and Co™ complexes of the ligand l,2-h«(8-aza-l,5-dithiacycIodecanyI)ethane ([lOlaneSjN earmuff) were synthesised and characterised. The ligand coordinates to Co™ in IV a pseudo five coordinate manner as determined by NMR spectroscopy. A solvent molecule or anion is likely to be coordinated to the Co*" centre in order to achieve distorted octahedral coordination. The complexes were characterised by FAB MS, electronic spectroscopy, elemental analysis and ESR spectroscopy. Although the Concentre was found to be in the low spin state, the electron transfer self exchange rate constant could not be determined by NMR spectroscopy. The Pd“ complex of this ligand was also synthesised and found to coordinate in a five coordinate marmer. 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 [PdCflOJaneSjN earmuff)]^^ complex. The potentially binuclear ligand, l,9-h«(4-aza-l,8-dithiacyclononane)-4,7-diaza-2,8-dione nonane, was synthesised and characterised. Preliminary results indicate that reaction with two equivalents of nickel(II) produced a binuclear complex. Examiners: Dr. A. McAuley, Supervisor (Department of Chemistry) ________________ Dr. K.R. Di5com D^artnienWiPleSEer^epartment of Chemis Dr. D.J. Berg, Departmenp^i^ember (D e^to en t of Chemistry) Dr. G. A. Beer, Outside Member (Department of Physics) Departmrat ofDr. C Orvig, External Examiner (DepartmentDepartmrat of Chemistry, ofDr. University of British Columbia) TABLE OF CONTENTS Abstract a Table of contents V List of Tables xiv List of Rguies xvi List of Schemes XX List of Abbreviations xxi Acknowledgements xxiii Dedication xxiv Chapter 1 Introduction 1 1.1 The origins of macrocyclic chemistry 2 1.2 Nomenclature of macrocyclic ligands 6 1.3 The thermodynamic stability and kinetic inertness of macrocyclic ligand complexes 7 1.3.1 Thermodynamic stability 7 1.3.2 Kinetic inertness 10 1.4 The implications of the macrocyclic effect 11 1.5 Synthesis of macrocyclic ligands 19 1.5.1 High dilution techniques 20 1.5.2 Template reactions 21 1.5.3 Rigid group synthesis 22 1.5.4 Synthetic strategies used to obtain polycycles 23 1.6 Methods used in the characterisation and study of macrocyclic complexes 24 1.6.1 Nuclear magnetic resonance 24 1.6.2 Electronic spectra 24 1.6.3 Electron paramagnetic resonance spectroscopy 25 VI 1.6.4 Mass spectrometry 26 1.6.5 Electrochemistry 27 1.7 Objectives of the research 29 Chapter 2 Synthesis and Characterisation of the Copper(II), NickeI(II), PaUadium(H) and CobaIt(ni) Complexes of the [lOJaneNjO ligand 32 2.1 Introduction 33 2.2 Synthesis of l-oxa-4,8-diazacyclodecane ([lOjaneNjO) 34 2.3 The copper(II) complex of [lOjaneNîG 35 2.3.1 Synthesis of [CuCClOjaneNzOjjCClO^); 35 2.3.2 Crystallography 36 2.3.3 Solution studies 42 2.3.3.1 Electronic spectroscopy 42 2.3.3.2 Electron paramagnetic resonance spectroscopy 44 2.3.3.3 Electrochemistry 47 2.4 The nickel(n) complex of [lOjaneNjO 50 2.4.1 Synthesis of [Ni([ 1 0 ]aneN 2 0 )J(C 1 0 4 ) 2 50 2.4.2 Crystallography 50 2.4.3 Solution studies 52 2.4.3.1 Electronic spectroscopy 52 2.4.3.2 Electron paramagnetic resonance spectroscopy of [Ni([10]aneN2O)2]^ 55 2.4.3.3 Electrochemistry of [Ni([10]aneN2O)2]^^ 56 2.4.3.4 Decomposition of Ni“ and [Ni“ ([ 1 0 ]aneN 2 O)2 ] complex ions 57 2.5 The PalladiumCH) complexes of [ 1 0 ]aneN 2 O 59 2.5.1 Synthesis of (Pd([ 1 0 ]aneN 2 O)2 ]^^ complexes 59 2.5.2 Solution studies 59 v u 2.5.2.1 High résolution nuclear magnetic resonance studies 59 2.5.2 Electronic spectroscopy 64 2.5.2.S Electrochemistry 65 2.5.Z4 Electron paramagnetic resonance spectroscopy 67 2.6 The cobalt(III) complex of [lOJaneNjO 6 8 2.6.1 Synthesis of [CoCClOjaneNgO) jCQ O J, 6 8 2.7 Conclusions 69 Chapter 3 The Synthesis of the Tricyclo[ 10-14-lOjN^O; Macrocycle and Related Ligands 70 3.1 Introduction 71 3.2 Synthetic strategy 72 3.3 Template reaction of the [Cu([ 1 0 ]aneN 2 O)J^^ complex 73 3.3.1 Synthesis 74 3.3.2 NMR studies of the free ligand, [10]aneN;O earmuff 76 3.3.3 Studies of the copper complex, [Cu([ 1 0 ]aneN 2 O earmuff)](C1 0 j 2 79 3.3.3.1 Characterisation of the copper complex by mass spectrometry 79 3.3.3.2 Electronic spectra 79 3.3.3.3 Electron paramagnetic resonance spectroscopy 80 3.3.3.4 Cyclic voltammetry 81 3.4 Coping of cyclam with htr-(2-(methylsulfonyl)oxyethyl)ether in order to form polycyclic products 82 3.4.1 Synthesis 82 3.4.2 Characterisation of [Cu(bicyclo[ 1 2 - 1 2 ]N4 0 )]^‘^ by FAB mass spectrometry 8 8 3.4.3 Characterisation of the free bicyclo[ 1 2 - 1 2 ]N4 0 ligand by NMR 90 3.4.4 Solution studies 93 3.4.4. 1 Electronic spectra 93 VIU 3.4A2 Electron paramagnetic résonance spectroscopy 94 3.4A3 Cyclic voltammetry 95 3.5 Synthesis of 7,16-dioxa-lA10,13-tetraazatricyclo[11.5.3.3]octadecane (tricycIoClO-lAlOlN^O;) by fusion of [lOJaneNjO to 4,8-(dichloroacetyI)- I-oxaA 8 -diazadecane 96 3.5.1 Nuclear magnetic resonance studies 98 3.5.2 Protonation of the tricyclo[ 1 0 - lA 1 0 ]N^ 0 2 ligand 103 3.5.3 Synthesis of [Cu(tricyclo[ 1 0 - 1 A 1 0 ]N4 0 2 )](C1 0 4 ) 2 107 3.5.3. 1 Characterisation of [Cu(tricyclo[10-1 A 1 0 ]N4 O2 )](CIOJ2 108 3.5.3.2 Solution studies 108 3.5.3.2.1 Electronic spectra 108 5.5.3.2.2 Electron paramagnetic resonance spectra 110 3.5.3.2.3 Cyclic voltammetry and chemical reduction of the tricyclic copper(H) complexes 1 1 2 3.5.4 Synthesis of [Cu(tricyclo[10-1 A 1 0 ]N4 O2 hiî-amide)](C 1 0 4 ) 2 115 3.5.5 Synthesis of nickel(U) and cobalt(III) complexes of the tricyclo[ 1 0 -lA 1 0 ]N4 0 2 ligand 115 3.6 Conclusions 117 Chapter 4 Synthesis and Characterisation of the Cobalt(lII) complex of [ 1 0 ]aneS 2 N, and the Cobalt(n/ni) and Palladium(II) complexes of [ 1 0 ]aneS 2 N earmuff 119 4.1 Introduction 120 4.2 Synthesis of the ligand [ 1 0 ]aneS 2 N 1 2 2 4.3 Synthesis of [Co([ 1 0 ]aneS 2 N)J(C 1 0