During the last decades the specific manipulation of matter on the (sub-) nanometer scale, also known as nanoscience, became possible by technologies such as the scanning tunneling microscope. Nanocatalysts, i.e. catalytic active structures of up to a few nanometers in size, belong to this rather new class of materials. Unlike ordinary ’macroscopic’ catalytic materials, the performance of nanocatalysts does not simply scale, for instance, with the surface to volume ratio of the active material. In this Thesis model nanocatalysts are investigated by means of ab-initio density functional theory calculations. In paper I, we explain the experimentally observed catalytic characteristics of small gold clusters, Au1-4, on a regular magnesium oxide terrace towards the oxidation of carbon monoxide by thoroughly studying the adsorption of CO and O2 on these clusters. In the subsequent paper II, we study the feasibility of a catalytic water-mediated CO oxidation reaction on Au1-4/MgO and find that this reaction mechanism is not assessable for Au2,4/MgO and unlikely for Au1,3/MgO. Papers III and IV concentrate on the reactivity of clusters in the gas phase. Particularly, we focus on the relative stability of Au13 isomers and its potential for O2 dissociation (paper III). We find the lowest energy isomers, which contain a triangular prism at their center surrounded by a ring of the remaining seven atoms, to be generally stable upon O2 adsorption. The dissociation of O2 at certain sites of Au13 is found to be exothermic. In paper IV we performed scans of the Born-Oppenheimer potential energy surfaces of neutral and charged Cu3, Ag3, and Au3 to explore the thermally excited vibrations of these trimers. While the Born-Oppenheimer surface of Cu3 exhibits one fairly deep energy minimum, it is comparatively flat with two shallow minima in the case of Ag3. Hence for Ag3 there exist many thermally accessible geometries in a wide range of angles and bond lengths. For Au3, two distinct energy minima appear, being well-separated by a barrier of 180 meV. Already at room temperature, we find bond lengths changes of up to 5% for the studied trimers. Choosing Au3 as a case study for the changed reactivity of thermally excited modes, we find CO to bind up to 150 meV stronger to the excited cluster. Gold deposited on graphene and graphite was observed to form larger aggregates. In paper V, we study the electronic structures, high mobility, and substrate-mediated clustering processes of Au1-4 on graphene. Already in the 1970s is was speculated that dispersion forces, i.e. van der Waals forces, significantly contribute to the adsorption energies of gold atoms on graphite. We accounted for van der Waals interactions in our density functional theory calculations (paper VI) and investigated the influence of these dispersion forces on the binding of copper, silver, and gold adatoms on graphene. While copper and gold show a mixed adsorption mechanism, i.e. chemical binding plus attraction due to the van der Waals forces, silver is purely physisorbed on graphene. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 719

This work comprises two main parts. The first part outlines our efforts to expand on the recent work of Gütlich et.al. by synthesizing Co(II) based spin crossover systems within a dendritic framework. We wanted to investigate the possibility of synthesizing different first generation, triazole containing dendrimers using “click” type reactions and their coordination ability with Co(II) ions. To this end we have had limited success mainly due to the numerous challenges in synthesizing a pure dendrimer product. The second part details our efforts in the synthesis of a mononuclear Co(II) based single molecule magnet. This comes as an extension to recent reports by Chang and Long where they have successfully obtained mononuclear Fe(II) single molecule magnets by inducing structural distortions within the complexes to amplify the spin-orbit coupling. We postulated that the use of Co(II) in conjunction with a bulky ligand framework would lead to desirable magnetic properties. We chose the known bis(imino)pyridine ligand scaffold due to its rich chemistry and its interesting and unexpected coordination behaviour, as we have seen in previous research efforts by our lab. To this end we were successful in isolating and characterizing 4 compounds, and we have carried out detailed magnetic measurements on the two most magnetically interesting species.

Neste trabalho foram estudadas as fases topológicas não triviais presentes em sistemas formados pela deposição de átomos de grafeno. Encontramos que quando um átomo hibridiza fortemente com o grafeno, apresenta um momento magnético e um forte spin-órbirta é possível a formação de uma rede hexagonal de baricentros que efetivamente gera uma estrutura de bandas característica de um efeito hall quântico anômalo. Especificamente, determinamos que o Ru satisfaz estas características. Quando este metal é depositado em uma configuração triangular no grafeno ocorrem picos na densidade de estados localizados no centro geométrico (baricentro) dos triângulos formados pelos Ru. Estes picos estão distribuídos de forma hexagonal e efetivamente geram uma estrutura de bandas que nas proximidades do nível de Fermi apresenta uma configuração de spin característica do efeito Hall quântico anômalo. Adicionalmente, encontramos que o sistema composto pela absorção de Ba ou Sr no grafeno favorece a formação do efeito Hall quântico de spin. Neste sistema, o acoplamento spin-órbita (SOC) gera um gap mais de 1000 vezes maior ao período no grafeno prístino. Para o estudo destes sistemas, implementamos no código SIESTA a aproximação on-site do acoplamento spin-órbita via o formalismo dos pseudopotenciais relativísticos de norma conservada. Nossa implementação foi testada a partir do estudo de fenômenos já conhecidos: i) o strong spin-splitting gerado no grafeno pela adsorção de Au, ii) o efeito hall quântico de spin no poço quântico de HgTe/CdTe e, iii) a formação de estados topológicos na superfície do Bi2Se3 e as fases magnéticas deste material com átomos de Mn adsorvidos. / In this work, were studied the non-trivial topological phases present in systems formed by deposition of atoms in graphene. We found that when an atom hybridizes strongly with grapheme, has a magnetic moment and a strong spin-orbit it is possible the formation of a hexagonal network of barycentres that effectively generates a structure band characteristic of a quantum anomalous Hall effect. Specifically, we determined that Ru satisfies these characteristics. When this metal is deposited in a triangular configuration in grapheme, peaks occur in the density of localized states in the geometric center (centroid) of the triangles formed by Ru. These peaks are distributed in a hexagonal structure and effectively generates a band structure that near the Fermi level has a spin configuration characteristic of the spin quantum Hall effect anomalous. Additionally, we found that the system composed by the adsorption of Ba or Sr in grapheme, promotes the formation of spin quantum Hall effect. In this system, the spin-orbit coupling (SOC) generates a gap more than 1000 times grater that predicted in pristine praphene. To study these systems, wu implemented in the code SIESTA the on-site approach of the spin-orbit coupling throught the formalism of norm conserved relativistic pseudo potentials. Our implementation was tested from the study of phenomena already known: i) the strong spin-splitting generated in graphene by adsorption of Au, ii) the quantum spin Hall effect in quantum well of HgTe / CdTe and, iii) formation of topological states in the surface of Bi2Se3 and the magnetic of this material with Mn atoms adsorved.

Cette thèse porte sur la manipulation du moment angulaire de la lumière à l'échelle sub-micronique. Le moment angulaire total de la lumière est composé d'une partie de spin, relié au degré de liberté de polarisation circulaire de la lumière, et d'une partie orbitale, relié au degré de libertés spatiaux de la lumière que sont sa direction de propagation (locale et globale) et sa distribution spatiale d'intensité. Le couplage spin-orbite existant entre ces deux contributions permet alors de manipuler les degrés de libertés spatiaux de la lumière par un simple contrôle de son état de polarisation circulaire. Dans cette thèse, nous avons étudié et exploité ce couplage à l'échelle sub-micronique dans deux nouveaux phénomènes que nous avons mis en évidence. Le premier met à profit ce couplage pour permettre d'exciter de manière unidirectionnelle des modes plasmoniques guidés. Une étude complète (numérique, expérimentale et analytique) de ce phénomène nouveau, basé sur un couplage entre le moment de spin du photon incident et le moment orbital extrinsèque des modes plasmoniques guidés dans la courbure d'un guide, est présentée. La deuxième étude présente une voie pour tirer parti du transfert de moment orbital de la lumière à un gaz d'électrons libres dans un métal afin de générer et contrôler le sens et la géométries de boucles de courants sub-microniques dans des structures métalliques. Ce contrôle permettrait la génération d'optomaimants nanométriques, entièrement contrôlés par la lumière, pouvant être modulés aux fréquences optiques. Ce travail a été soutenu par le LABEX Action. / This thesis focuses on the manipulation of the angular momentum of light at the nanoscale.The total angular momentum of light is composed of a spin component, connected to the polarization degree of freedom of light, and an orbital component, related to the spatial degrees of freedom of the light which are its propagation direction (local and global) and its intensity distribution. The spin-orbit coupling between these two contributions allows the control of the spatial degrees of freedom of light by a simple manipulation of its circular polarization state. In this thesis, we have studied and applied this coupling at the nanoscale anbd we have highlighted two new phenomenas. The first one takes part of this coupling to allows unidirectional excitation of plasmonic guided modes. A complete study (numerical, experimental and analytical) of this new phenomenon, based on a coupling between the spin of the incident photon and the extrinsic orbital momentum of the plasmonic guided modes within the curvature of a waveguide, is presented. The second study propose a way to benefit from the transfer of the angular momentum of light to the free electrons gas in a metal to generate and control the direction and the geometry of nanoscale current loops in metallic structures. this control would at optical frequencies. This work was supported by the LABEX Action.

La signature spectroscopique des ions moléculaires est fondamentale pour l'étude et la caractérisation de plasma en astrophysique et en laboratoire. Différentes techniques peuvent être utilisées pour caractériser ces plasmas parmi lesquelles la spectroscopie de photoélectrons induits par rayons X et la photo-absorption X. L'objectif de cette thèse est la simulation des spectres de photo-absorption au seuil L (2p) des ions moléculaires de silicium SiHn+ (n= 1, 2, 3) et au seuil K (1s) des ions moléculaires de l'oxygène OHn+ (n=1, 2) et du carbone CHn+ (n= 1, 2) produits lors d'une décharge plasma. Nous avons développé différents protocoles numériques permettant de calculer les spectres d'absorption aux seuils K et L en combinant des méthodes de structures électroniques et de propagation de paquet d'ondes. Les optimisations de géométrie et le calcul des seuils d'ionisation (IP) sont obtenus en utilisant la théorie de la fonctionnelle de la densité (DFT). Les effets de relaxation électronique due à la formation d'un trou en couche interne sont pris en compte au niveau SCF (convergence de la fonction d'onde électronique à N-1 électrons). Les surfaces d'énergie potentielle (PES) et les moments de transition dipolaires sont calculés à un niveau Post-HF (Interaction de configurations, CI). L'introduction explicite du couplage spin-orbite à l'aide de l'opérateur Breit-Pauli est utilisée pour l'étude du processus d'excitation au seuil L du silicium. Les spectres théoriques calculés pour les différentes molécules étudiées présentent un accord raisonnable avec les mesures expérimentales. La présence d'états électroniques métastables produits lors de la décharge plasma est discutée. / Molecular ions cover important roles in study and characterization of astrophysical and laboratory plasma. To this purposes, different spectroscopic techniques are used among which we found the X-ray photoelectron spectroscopy and the X-ray photoabsorption spectroscopy. This PhD work is focused on the calculation of X-ray photoabsorption spectra of molecular ions of silicon, carbon and oxygen XHn+ (X= Si, C, O; n= 1, 2, 3). The former is excited on the L (2p) shell while the others on the K (1s) shell produced in plasma discharged. We developed numerical protocols which permits to compute with reasonable precision the K and L-shell photoabsorption spectra combining electronic structure and nuclear wavepacket propagation methods. The optimization of the geometries and the calculation of the ionization potentials (IP) are carried out using the density functional theory (DFT). The relaxation effects due to the core hole creation are taken into account at the self-consistent field (SCF) level. The potential energy surfaces (PES) and the dipole moment transitions are computed at the post Hartree-Fock (configuration interaction, CI) level. The spin-orbit coupling effect are explicitly taken into account through the Breit-Pauli operator. The theoretical results have been compared with the experimental data and they allow the interpretation of the experimental bands.

Cette thèse traite de l'application des approches topologiques de la liaison chimique à des systèmes contenant des éléments lourds sujets aux effets relativistes, notamment ceux dépendant du spin. Elle présente deux volets principaux : (i) l'évaluation des effets du couplage spin-orbite (SO) sur la structure électronique à l'aide d'une analyse combinée des propriétés de la fonction ELF et de l'approche QTAIM en deux composantes et (ii) la rationalisation des distorsions structurales pour des molécules impliquant des éléments lourds et le rôle du couplage SO dans ces distorsions. Nous avons pu mettre en évidence différentes situations pour lesquelles le couplage SO peut avoir une influence très importante, modérée ou négligeable. Un résultat important de ce travail démontre la dépendance du couplage SO à son environnement chimique. Pour le second volet, nous avons élaboré une approche qui a consisté à établir une corrélation entre les interactions électrostatiques locales entre régions liantes et non liantes (bassins ELF et QTAIM) et la géométrie moléculaire du système dans l'esprit des modèles VSEPR et du Ligand Close Packing (LCP). Cette approche a notamment mis en évidence la connexion entre la structure moléculaire et les répulsions des paires non-liantes de l'atome central avec leur environnement. / This thesis deals with the aplication of topological approaches of the chemical bonding by means of analysing properties of density-based functions like Electron Localization Function (ELF) and the Quantum Theory of Atoms in Molecumes (QTAIM) to systems involving heavy elements such as 6p elements or actinides . It is divided into two main parts: (i) the evaluation of the spin-orbit coupling (SOC) effects on the electronic structure by means of combination of the QTAIM and ELF topological analyses in the field of quasirelativistic quantum calculations, and (ii) the rationalization of structural distorsions on molecules containing heavy atoms, and the role of the SOC on these distorsions. We were able to emphasize different situations for which SOC has strong, moderate or tiny influence on the chemical bonding, depending on the chemical environnement on which the heavy element is involved. In the second part of this thesis we tested our approach consisting of ELF/QTAIM interbasin repulsion energy analysis in connection with the molecular geometry of the system, in the spirit of the VSEPR and LCP models.

L'importance des effets relativistes dans la chimie a été reconnu depuis les années 1980. Par exemple, sans la relativité (a) l'or aurait la même couleur que l'argent (b) le mercure ne serait pas liquide à la température ambiante et (c) nos voitures ne démarrent pas avec une batterie de plomb. Pour une description théorique de la structure et la réactivité des éléments lourds, la relativité est un ingrédient essentiel. Le hamiltonien pour les calculs moléculaires relativistes à 4 composantes est construit en remplaçant la partie mono-électronique de l'hamiltonien électronique non-relativiste par le hamiltonien de Dirac. La partie bi-électronique est approchée par le terme de r Coulomb comme dans le cas non relativiste, ce qui donnel'hamiltonien de Dirac-Coulomb (DC). Pour réduire le coût de calcul, on peut utiliser des hamiltoniens relativistes à 2 composantes. Parmi eux, l'hamiltonien exact à 2 composantes (X2C) est le plus précise. La corrélation électronique est, cependant, une contribution très importante pour obtenir une description théorique à la fois qualitative et quantitative des spectroscopies moléculaires, réactions, etc. Dans cette thèse, nous avons étudié l'interaction entre la relativité et de la corrélation. à la fois par des développements méthodologiques et par des applications moléculaires. Dans la première partie de la thèse, nous avons calculé les constantes spectroscopiques dimères des gaz rares lourds. La liaison faible de ces dimères ne peut être décrit que par l'inclusion de la corrélation électronique. Les dimères des gaz rares les plus lourds, le radon et l'eka-radon, nécessite de plus un traitement adéquat de la relativité. Nos calculs sont basés sur l'hamiltonien X2Cmmf, à la fois avec des méthodes de corrélation basés sur une fonction d'onde et séparation de porte (srDFT). La deuxième partie de cette thèse concerne la simulation de la spectroscopie des rayons X, où l'on sonde la région du cœur d'une molécule, ou la relativité joue un rôle très important. Nous avons étudié la spectroscopie L-edge de la série isoélectronique: UO22 +, UNO+, et UN2, où le couplage spin-orbite joue un rôle majeur. Au niveau des méthodes, nous avons considéré MP2 à couches ouvertes et la théorie de la fonctionnelle de la densité dépendante de temps (TDDFT). Dans un autre étude, nous avons simulé la spectroscopie K-edge de la série H2X (X = O, S, Se, Te) et XH3 (X = N, P, As) ainsi que les molécules N2 et N2O2. Pour ces systèmes, l'interaction spin-orbite est moins important. Par conséquent, nous avons utilisé un hamiltonien DC sans spin (SF). Certains des systèmes pris en compte dans ce travail sont de caractère multi-référentielles ; nous avons utilisé la methode Coupled Cluster Multi-référentielle de type State Universal et adapté au groupe unitaire (UGA-SUMRCC) comme une méthode de corrélation. Dans la troisième et partie principale de la thèse, l'attention est de nouveau sur la relativité et de la corrélation, mais pour le calcul des propriétés électriques et magnétiques moléculaires. Nous avons développé et mis en œuvre un module pour le calcul des valeurs moyennes au niveau relativiste à 4-composantes coupled cluster monoréferentiel. Les propriétés qui sondent la densité électronique près de noyaux (lourds), telles que la résonance paramagnétique électronique (RPE), les paramètres des gradients de champ électrique et la non-conservation de la parité (NCP) des molécules chirales ,sont parfaitement adaptés pour l'application de cette méthode. Pour l'instant, nous avons étudié que la NCP. Ce module dans le logiciel DIRAC pour les calculs moléculaires relativistes fournit un cadre propice pour la mise en œuvre de méthodes de CC relativistes employant la symétrie de groupes doubles et de permutation de manière très efficace. En perspective, nous ciblons la mise en œuvre de la réponse linéaire CC pour le calcul des énergies d'excitation et propriétés moléculaires de second ordre tels que les paramètres de RMN. / The importance of relativistic effects in chemistry has been recognized since the 1980s. Without relativity (a) gold would have the same colour as silver (b) mercury would not be liquid at room temperature (c) our cars would not start (lead-battery). For a theoretical description of the structure and reactivity of heavy-elements, relativity is considered as an essential ingredient. The Hamiltonian for the 4-component relativistic molecular calculations is constructed by replacing the one-electronic part of the non-relativistic molecular Hamiltonian by the Dirac Hamiltonian. The two-electronic part of the Hamiltonian is approximated by the Coulombic repulsion term as in the non-relativistic case. The resulting Hamiltonian is called the Dirac-Coulomb (DC) Hamiltonian. For chemical applications there exist a class of relativistic Hamiltonians, where one-electronic part of the DC Hamiltonian is transformed to a 2-component one. Among them the eXcact 2-component (X2C) Hamiltonian is the most accurate one. Electron correlation, however, is a very important contribution to achieve a both qualitative and quantitative correct description of molecular spectroscopies, reactions etc. It is, therefore, essential to study the interplay between relativity and correlation. In this thesis, we have studied this interplay both in terms methodological developments and molecular applications. In the first part of the thesis we have studied the spectroscopic constants of the heavy rare gas dimers. The weak bonding of those dimers can only be described by the inclusion of electron correlation. The heavier analogues in the rare gas series i.e, Radon and eka-Radon, in addition require adequate treatment of relativity. Our calculations are based on the eXact 2-Component molecular-mean field (X2Cmmf) Hamiltonian both with wave function methods and range-separated DFT methods. The second part of this thesis simulates X-ray spectroscopy, where one probes the core region of a molecule. In the core region relativity plays a very significant role. Removal and excitation of electrons from that region involve various processes, which are beyond a mean-field description. We have studied L-edge spectroscopy of the isoelectronic series: UO22+, UNO+, and UN2, where spin-orbit coupling plays a major role. For the theory we have considered single reference open-shell MP2 and Time Dependent Density functional Theory (TDDFT). In another work, we have studied K-edge spectroscopy of the H2X (X= O, S, Se, Te) and XH3 (X= N, P, As) series as well as N2, N2O2 molecules. For this study spin-orbit coupling is less important, therefore, we have treated them with the Spin-Free (SF) DC Hamiltonian. Some of the systems considered in this work are Multi-Reference in nature; we have used Unitary Group Adapted (UGA) State Universal Multi-reference Coupled Cluster (UGA-SUMRCC) theory as a correlation method. In the third and major part of the thesis, the thrust is again on relativity and correlation, but for the calculation of molecular electric and magnetic properties. We have developed and implemented a module for the calculation of expectation values at the 4-component Relativistic Single Reference Coupled Cluster level. Properties that probe the electron density near (heavy) nuclei, such as Electron Paramagnetic Resonance (EPR) parameters, electric field gradients and parity non-conservation (PNC) in chiral molecules are ideally suited for the application of this method. However, we have only studied PNC so far. This module in the DIRAC software for relativstic molecular calculations provides a convenient framework for the implementation of relativistic CC methods employing double group and permutation symmetry very efficiently. In the near future we therefore target the implementation of Linear Response CC for the calculation of excitation energies and second-order molecular properties such as NMR parameters.

Cette thèse porte principalement sur l'étude de modèles de fermions en interactions contenant un couplage spin-orbite. Ces modèles (i) peuvent décrire une classe de matériaux composés d'iridates sur le réseau en nid d'abeille ou (ii) pourraient être réalisés artificiellement dans des systèmes d’atomes froids. Nous avons étudié, dans un premier temps, le système à demi-remplissage avec l'interaction de Hubbard et un couplage spin-orbite anisotrope. Nous avons trouvé plusieurs phases: la phase isolant topologique pour de faibles corrélations, et deux phases avec des ordres magnétiques frustrés, l'ordre de Néel et l'ordre spiral, dans la limite de très fortes corrélations. La transition entre les régimes de faibles et de fortes corrélations est une transition de Mott dans laquelle les excitations électroniques se fractionnent en excitations de charge et de spin. Les charges sont localisées par l'interaction. Le secteur de spin présente de fortes fluctuations qui sont modélisées par un gaz d’instantons. Nous avons ensuite exploré la physique d'un système régi au demi-remplissage par le modèle de Kitaev-Heisenberg, qui présente une phase magnétique de type zig-zag. En dopant le système, autour du quart remplissage, la structure de bande présente de nouveaux centres de symétrie en plus de la symétrie d'inversion. Le couplage de spin de Kitaev-Heisenberg favorise alors la formation de paires de Cooper dans un état triplet autour de ces centres de symétrie. La condensation de ces paires de Cooper autour de ces vecteurs d'onde non triviaux se manifeste par une modulation spatiale du paramètre d'ordre supraconducteur, comme dans la supraconductivité de Fulde–Ferrell–Larkin–Ovchinnikov (FFLO). La dernière partie de la thèse propose et étudie une implémentation des phases topologiques dite de Haldane et de Kane-Mele dans un système avec deux espèces de fermions sur le réseau en nid d'abeille, stabilisée grâce à l’interaction RKKY médiée par l’espèce rapide et qui agit sur l’espèce lente. / This thesis is dedicated largely to the study of theoretical models describing interacting fermions with a spin-orbit coupling. These models (i) can describe a class of 2D iridate materials on the honeycomb lattice or (ii) could be realized artificially in ultra-cold gases in optical lattices. We have studied, in the first part, the half-filled honeycomb lattice model with on-site Hubbard interaction and anisotropic spin-orbit coupling. We find several different phases: the topological insulator phase at weak coupling, and two frustrated magnetic phases, the Néel order and spiral order, in the limit of strong correlations. The transition between the weak and strong correlation regimes is a Mott transition, through which electrons are fractionalized into spins and charges. Charges are localized by the interactions. The spin sector exhibits strong fluctuations which are modeled by an instanton gas. Then, we have explored a system described by the Kitaev-Heisenberg spin Hamiltonian at half-filling, which exhibits a zig-zag magnetic order. While doping the system around the quarter filling, the band structure presents novel symmetry centers apart from the inversion symmetry point. The Kitaev-Heisenberg coupling favors the formation of triplet Cooper pairs around these new symmetry centers. The condensation of these pairs around these non-trivial wave vectors is manifested by the spatial modulation of the superconducting order parameter, by analogy to the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) superconductivity. The last part of the thesis is dedicated to an implementation of the Haldane and Kane-Mele topological phases in a system composed of two fermionic species on the honeycomb lattice. The driving mechanism is the RKKY interaction induced by the fast fermion species on the slower one.

This work comprises two main parts. The first part outlines our efforts to expand on the recent work of Gütlich et.al. by synthesizing Co(II) based spin crossover systems within a dendritic framework. We wanted to investigate the possibility of synthesizing different first generation, triazole containing dendrimers using “click” type reactions and their coordination ability with Co(II) ions. To this end we have had limited success mainly due to the numerous challenges in synthesizing a pure dendrimer product. The second part details our efforts in the synthesis of a mononuclear Co(II) based single molecule magnet. This comes as an extension to recent reports by Chang and Long where they have successfully obtained mononuclear Fe(II) single molecule magnets by inducing structural distortions within the complexes to amplify the spin-orbit coupling. We postulated that the use of Co(II) in conjunction with a bulky ligand framework would lead to desirable magnetic properties. We chose the known bis(imino)pyridine ligand scaffold due to its rich chemistry and its interesting and unexpected coordination behaviour, as we have seen in previous research efforts by our lab. To this end we were successful in isolating and characterizing 4 compounds, and we have carried out detailed magnetic measurements on the two most magnetically interesting species.

No description available.