Disclosing the multi-faceted world of weakly interacting inorganic systems by means of NMR spectroscopy

The potential of NMR spectroscopy to investigate inorganic systems assembled by, or whose reactivity is affected by, non-covalent interactions is described. Subjects that have received particular attention in recent years (halogen bonding and Frustrated Lewis Pairs) and more classical subjects that remain under-explored (self-aggregation of ion pairs in low polar solvents, behavior of MAO containing metallocenium ion pairs, and hydrogen bonding/ion pairing effects in Au(I) catalysis) are considered, using an innovative approach, always focusing on the crucial information that can be provided by NMR

Building a Better Halide Receptor: Optimum Choice of Spacer, Binding Unit, and Halosubstitution

Quantum calculations are used to measure the binding of halides to a number of bipodal dicationic receptors, constructed as a pair of binding units separated by a spacer group. A number of variations are studied. A H atom on each binding unit (imidazolium or triazolium) is replaced by Br or I. Benzene, thiophene, carbazole, and dimethylnaphthalene are considered as spacer groups. Each receptor is paired with halides F-, Cl-, Br-, and I-. I-substitution on the binding unit yields a large enhancement of binding, as much as 13 orders of magnitude; a much smaller increase occurs for bromosubstitution. Imidazolium is a more effective binding agent than is triazolium. Benzene and dimethylnaphthalene represent the best spacers, followed by thiophene and carbazole. F- binds much more strongly than do the other halides which obey the order Cl- \u3e Br- \u3e I-

N-Aryl-9,10-phenanthreneimines as scaffolds for exploring non-covalent interactions: a structural and computational study

A series of 10-[(4-halo-2,6-diisopropylphenyl)imino]phenanthren-9-ones and derivatives of the phenanthrene-9,10-dione ligand have been synthesised and structurally characterised to explore two types of noncovalent interactions, namely the influence of the steric bulk upon the resulting C–H···π and π-stacking interactions and halogen bonding. Selected noncovalent interactions have additionally been analysed by DFT and AIM techniques. No halogen bonding has been observed in these systems, but X lone pair···π, C–H···O=C and C–H···π interactions are the prevalent ones in the halogenated systems. Removal of the steric bulk in N-(2,4,6-trimethylphenyl)-9,10-iminophenanthrenequinone affords different noncovalent interactions, but the C–H···O=C hydrogen bonds are observed. Surprisingly, in N-(2,6-dimethylphenyl)-9,10-iminophenanthrenequinone and N-(phenyl)-9,10-iminophenanthrenequinone these C–H···O=C hydrogen bonds are not observed. However, they are observed in the related 2,6-di-tert-butylphenanthrene-9,10-dione. The π-interactions in dimers extracted from the crystal structures have been analysed by DFT and AIM. Spectroscopic investigations are also presented and these show only small perturbations to the O=C–C=N fragment

Self-complementary nickel halides enable multifaceted comparisons of intermolecular halogen bonds : fluoride ligands vs other halides

The syntheses of three series of complexes designed with self-complementary motifs for formation of halogen bonds between an iodotetrafluorophenyl ligand and a halide ligand at square-planar nickel are reported, allowing structural comparisons of halogen bonding between all four halides C6F4IX–Ni (X = F, Cl, Br, I). In the series, trans-[NiX(2,3,5,6-C6F4I)(PEt3)2] 1pX and trans-[NiX(2,3,4,5-C6F4I)(PEt3)2] (X = F, Cl, Br, I) 1oX, the iodine substituent on the benzene ring was positioned para and ortho to the metal, respectively. The phosphine substituents were varied in the series, trans-[NiX(2,3,5,6-C6F4I)(PEt2Ph)2] (X = F, I) 2pX. Crystal structures were obtained for the complete series 1pX, and for 1oF, 1oCl, 1oI and 2pI. All these complexes exhibited halogen bonds in the solid state, of which 1pF exhibited unique characteristics with a linear chain, the shortest halogen bond d(C6F4IF–Ni) = 2.655(5) Å and the greatest reduction in halogen bond distance (IF) compared to the sum of the Bondi van der Waals radii, 23%. The remaining complexes form zig-zag chains of halogen bonds with distances also reduced with respect to the sum of the van der Waals radii. The magnitude of the reductions follow the pattern F > Cl ~ Br > I, 1pX > 1oX, consistent with the halogen bond strength following the same order. The variation in the IX–Ni angles is consistent with the anisotropic charge distribution of the halide ligand. The temperature dependence of the X-ray structure of 1pF revealed a reduction in halogen bond distance of 0.055(7) Å on cooling from 240 to 111 K. Comparison of three polymorphs of 1oI shows that the halogen bond geometry may be altered significantly by the crystalline environment. The effect of the halogen bond on the 19F NMR chemical shift in the solid state is demonstrated by comparison of the magic-angle spinning NMR spectra of 1pF and 1oF with that of a complex incapable of halogen bond formation, trans-[NiF(C6F5)(PEt3)2] 3F. Halogen bonding causes deshielding of iso in the component of the tensor perpendicular to the nickel coordination plane. The results demonstrate the potential of fluoride ligands for formation of halogen bonds in supramolecular structures

Self-Assembly von Metallo-Supramolekularen Architekturen und Massenspektrometrie von Bismut-Oxido-Clustern

0\. Summary / Zusammenfassung 11 0.1 Summary (English) 11 0.2 Zusammenfassung (Deutsch) 13 1\. Introduction to Supramolecular Chemistry 15 2\. Aim of this Study 17 3\. Theoretical Background 19 3.1 Coordination Chemistry 19 3.2 Self- Processes 22 3.2.1 Self-Assembly and Self-Organization 22 3.2.2 Self-Sorting 27 3.3 Metallo-Supramolecular Self-Assembly: A Brief Overview 29 3.3.1 Introduction to Metallo-Supramolecular Self-Assembly 29 3.3.2 Structural Insights into Metallo-Supramolecular Assemblies: From Small Dinuclear Macrocycles to Large Three-Dimensional Architectures 35 3.3.3 Functionalized Metallo-Supramolecular Systems 45 3.3.4 Metallo-Supramolecular Complexes Acting as Microreactors 50 4\. Mass Spectrometry 54 4.1 Mass Spectrometry in Supramolecular Chemistry: Ionization and Detection 54 4.2 ESI-FTICR Mass Spectrometry 56 4.3 Manipulation of Ions in the Gas Phase: Tandem Mass Spectrometry and Gas-Phase Chemistry 60 4.4 The Use of a Micro-Reactor – Online Mass Spectrometry 63 4.5 ESI MS as a Tool in Metallo-Supramolecular Chemistry 64 5\. Self-Assembly of Metallo-Supramolecular Architectures 67 5.1 Synthesis of Stang-Type Metal Centers 67 5.2 Self-Assembly as a Tool to Form Metallo-Supramolecular Complexes 69 5.2.1 The Self-Assembly of Metallo- Supramolecular M2L2 Complexes and Their Corresponding M4L4 Catenanes 69 5.2.2 Equilibria between Metallo-Supramolecular Triangles and Squares 77 5.2.3 The Influence of Small Constitutional Changes at the Formation of Metallo- Supramolecular Boxes 95 5.3 The Self-Assembly of Urea-Functionalized Metallo- Supramolecular Complexes 107 5.3.1 Bispyridyl-Urea Ligands – Synthesis and Structure 107 5.3.2 The Self-Assembly of Bispyridyl-Urea based M2L2 Complexes and their Equilibria with the Corresponding M3L3 Complexes 122 5.3.3 The Self- Assembly of Small Functionalized Metallo-Supramolecular Cages 143 5.4 Thermodynamically Controlled Self-Sorting of Homo- and Hetero-Bimetallic Metallo-Supramolecular Macrocycles 156 5.5 Investigation into the Mechanisms of Self-Assembly Reactions 165 5.5.1 Kinetic and Structural Investigation of the Self-Assembly of Metallo-Supramolecular Pt(II) Complexes 165 5.5.2 Online Mass Spectrometry: The Use of a Micro-Reactor to Examine Fast Metallo- Supramolecular Self-Assembly Processes 182 6\. ESI Mass Spectrometry of Bismuth-Oxido Clusters 197 7\. Outlook 208 8\. Experimental Part 210 8.1 General Techniques and Materials 210 8.2 List of Abbreviations 212 8.3 Syntheses of Organic Ligands 215 8.4 Syntheses of Metal Centers 226 8.5 Self- Assembly of Metallo-Supramolecular Complexes 233 8.5.1 Self-Assembly of M2L2 Complexes and their Catenanes 233 8.5.2 Self-Assembly of Metallo- Supramolecular Triangles and Squares 245 8.5.3 Self-Assembly of Small Metallo- Supramolecular Cages 248 8.5.4 Self-Assembly of M2L2 and M3L3 Complexes Based on Bispyridyl-Urea Ligands 252 8.5.5 Self-Assembly of Bispyridyl-Urea Based M2L4 and M3L6 Complexes 263 8.5.6 Self-Assembly and Self-Sorting of Homo- and Heterometallic M4L2 Complexes 267 8.5.7 Self-Assembly of Platinum-Containing Metallo-Supramolecular Macrocycles 272 8.6 Capillary Parameter for the Online Mass Spectrometric Experiments Using a Micro-Reactor 276 8.7 Mass Spectrometry of Bismuth-Oxido Clusters 277 8.8 Data of Crystal Structures 295 9.8.1 1,3-bis(2-methylpyridin-3-yl)urea 163 295 9.8.2 1,3-bis(4-methylpyridin-3-yl)urea 164 296 9.8.3 1,3-bis(5-methylpyridin-3-yl)urea 165 297 9.8.4 1,3-bis(6-methylpyridin-3-yl)urea 166 298 9.8.5 M2L2 complex [((en)Pd)2(165)2](NO3)4 171 299 9.8.6 M2L2 complex [((dppp)Pd)2(162)2](OTf)4 174a 300 9.8.7 M2L2 complex [((dppp)Pd)2(164)2](OTf)4 175a 301 9.8.8 M2L2 complex [((dppp)Pd)2(168)2](OTf)4 178 302 9\. References 303 10\. Acknowledgements 328 11\. Curriculum Vitae 330 11\. List of Publications and Presentations 332In the first part of this thesis, the principles of metallo-supramolecular self-assembly and self-sorting were studied. Depending on the properties of the building blocks used, many different metallo-supramolecular complexes were obtained and their properties were investigated using a combination of several analytic methods. In order to get functionalized complexes which can interact with guest molecules, several bispyridyl-urea ligands have been synthesized and used for self-assembly. Due to their ability to act as hydrogen-bond donor and acceptor and their dipole moment in the urea groups, these ligands are promising candidates for molecular recognition. Unfortunately, the solubility of the complexes was very low which hampers their use for molecular recognition. In many systems equilibria between two complexes were observed, which are based on a sensitive balance between enthalpy and entropy that can be influenced by the properties of their building blocks as well as by their environment. In principle, the larger complexes were favored at low temperatures and high concentrations, while the corresponding smaller complexes were favored vice versa. A drastic solvent effect was observed for the self-assembly of flexible divalent ligands with (en)Pd(NO3)2 in water. The formation of M2L2 complexes in equilibrium with their corresponding M4L4 catenanes was discovered, while the entropically more favorable M3L3 complexes were not observed. This can be assigned to hydrophobic effect which favors the formation of catenanes. Interestingly, 1:1:1 mixtures of 4,4´-bis(pyridine-4-ylethynyl)-2,2´-bipyridin with the metal centers (dppp)M(OTf)2 and (dppe)M(OTf)2 (M = Pd2+, Pt2+) showed self-sorting behavior. While (dppp)M(OTf)2 preferred coordination at the pyridine binding sites of the ligand, (dppe)M(OTf)2 showed no preference. This was used for the self- sorting of homo- and heterometallic M4L2 complexes and nicely shows the influence an additional CH2-group can have on self-assembly processes. Kinetic studies of the formation of several Pt(II) and Pd(II) complexes revealed that the coordination of the ligands to the metal centers is fast, whereas the error correction process is slower than that. Thus, some kinetically formed complexes were observed which convert into the thermodynamically favored complexes over time. Mixed-flow on-line mass spectrometry was successfully used to monitor fast self-assembly processes and identify intermediates of the self-assembly processes including the initial coordination. For the self- assembly reactions many different intermediates were observed and thus the process is rather unspecific, whereas self-sorting processes were found to be pathway-selective. Comparing the assemblies of isomeric ligands with each other shows that the constitution of the ligand has a drastic effect on the resulting assemblies. The complexes formed can be isomeric to each other or totally different. It was discovered, that the behavior of isomeric complexes depends highly on their constitution. For example, tandem MS experiments showed that isomeric complexes can undergo fragmentation using totally different pathways. The second part of the thesis deals with the analysis of bismuth-oxido clusters using ESI MS. Several bismuth-oxido clusters bearing different cluster cores as well as different ligands have been analyzed successfully. Tandem MS experiments confirmed their structure and enabled to investigate their stability. ESI MS has been shown to be a suitable analytical method to examine bismuth-oxido clusters.Im ersten Teil dieser Arbeit wurden die Grundlagen metallo-supramolekularer Selbst-Assemblierung und Selbst-Sortierung untersucht. Die Kombination verschiedener Baueinheiten führte zur Ausbildung einer Vielzahl unterschiedlicher Komplexe, deren Eigenschaften durch die Kombination mehrerer analytischer Methoden untersucht wurden. Um funktionalisierte Komplexe zu erhalten, welche in der Lage sind Gast-Moleküle zu erkennen, wurden mehrere Bispyridylharnstoff-Liganden hergestellt. Harnstoffe besitzen ein relativ hohes Dipolmoment und können bei der Ausbildung von Wasserstoff-Brücken sowohl als Donor als auch als Akzeptor fungieren, was sie zur molekularen Erkennung prädestiniert. Leider verhindert die geringe Löslichkeit der resultierenden Komplexe ausführliche Studien. In vielen Systemen wurden Gleichgewichte zwischen unterschiedlichen Komplexen gefunden, die auf einem empfindlichen Zusammenspiel von Enthalpie und Entropie beruhen, das sowohl durch die Eigenschaften der einzelnen Baueinheiten als auch durch die Umgebung beeinflusst wird. Generell sind größere Komplexe bei niedrigen Temperaturen und hohen Konzentrationen bevorzugt, während sich die kleineren Komplexe entgegengesetzt verhalten. Ein drastischer Lösungsmittel-Effekt wird für die Selbst-Assemblierung flexibler divalenter Liganden mit (en)Pd(NO3)2 in Wasser beobachtet. Hier werden Gleichgewichte zwischen M2L2-Komplexen und ihren M4L4-Catenanen beobachtet, während die entropisch bevorzugten M3L3-Komplexe nicht auftreten. Dies kann mit Hilfe des hydrophoben Effekts erklärt werden, welcher die Ausbildung der Catenane bevorzugt. Wenn 4,4´-Bis(pyridin-4-ylethynyl)-2,2´-bipyridin in einem 1:1:1-Verhältnis mit den Metallzentren (dppp)M(OTf)2 und (dppe)M(OTf)2 (M = Pd2+, Pt2+) kombiniert wird, werden Selbst-Sortierungs-Prozesse beobachtet. (dppp)M(OTf)2 koordiniert bevorzugt an die Pyridine des Liganden, während (dppe)M(OTf)2 keine Präferenz zeigt. Dies konnte für die Darstellung von homo- und heterometallischen M4L2-Komplexen über Selbst-Sortierungs-Prozesse genutzt werden. Durch zeitabhängige Untersuchungen der Bildung verschiedener Pt(II)- und Pd(II)- Komplexe konnte gezeigt werden, dass die Koordination der Liganden an die Metallzentren sehr schnell erfolgt, während die anschließende Fehler-Korrektur langsamer verläuft. Auf Grundlage dessen konnten verschiedene kinetisch gebildete Komplexe identifiziert werden, welche sich mit der Zeit in die thermodynamisch bevorzugten Strukturen umwandelten. Schnelle Selbst- Assemblierungs-Prozesse wurden erfolgreich mit Hilfe der „Mixed-Flow online Massenspektrometrie“ untersucht, wodurch neben verschiedenen Intermediaten selbst die sehr schnelle Koordination beobachtet werden konnte. Während sich bei Selbst-Assemblierungs-Prozessen eine Vielzahl an Intermediaten ausbildete und die Prozesse daher eher unspezifisch sind, scheint die Bildung von Komplexen in Selbst-Sortierungs-Prozessen spezifisch zu sein. Vergleicht man die Selbst-Assemblierungs-Prozesse isomerer Liganden mit denselben Metallzentren miteinander, so zeigt sich, dass die Konstitution der Liganden die Bildung der resultierenden Komplexe teils drastische beeinflusst. Hierbei können diese Komplexe sowohl isomer zueinander sein als auch völlig verschiedene Strukturen besitzen. Die Eigenschaften isomerer Komplexe unterscheiden können sich ebenfalls, so konnte zum Beispiel über MS/MS- Experimente gezeigt werden, dass isomere Komplexe völlig unterschiedliche Zerfallsmechanismen besitzen können. Der zweite Teil dieser Arbeit beschäftigt sich mit der Analyse von Bismut-Oxido-Clustern mittels ESI-MS. Die untersuchten Cluster unterschieden sich dabei in ihrem Cluster-Kern und in der Art ihrer Liganden. Tandem MS-Experimente ermöglichten sowohl die Strukturaufklärung der Cluster als auch Untersuchungen bezüglich deren Stabilität. Es wurde gezeigt, dass ESI-MS eine gute analytische Methode ist, um solche Cluster zu untersuchen

Inhemska preferensers påverkan på Internationella protokoll : En jämförande analys av Australiens och Kanadas inblandning i Kyotoprotokollet

Syftet med den här uppsatsen var att analysera vilka inhemska intressen som kan tänkas påverka nationalstaters ställningstagande i relation till Kyotoprotokollet. Detta har gjorts genom att svara på olika frågeställningar om varför länderna valde att agera som gjorde. Dessutom har det besvarats på vilket sätt ländernas agerande kan kopplas till den internationella, respektive den inhemska arenan. Uppsatsen har även besvarat hur internationella avtal påverkas av att länder väljer att ansluta sig respektive hoppa av avtalen