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The major focus of this thesis involves a new approach to spin-crossover (SCO) in iron(II) dinuclear complexes. In order to acquire SCO properties, a series of novel ligands (L1M, L2M, L3M, L4M), together with the corresponding iron(II) and/or nickel(II) complexes were synthesized and characterized. Beyond the successful synthesis and characterization of these ligands, some interesting aspects of their synthesis are discussed. The reported ligands are methyl-derivatives from ligands previously studied in the group. The methyl group in the position 6 of the pyridine group is introduced to induce steric hindrance in the complexes and decrease the ligand field strength. As a result, the influence of the methyl group may induce SCO in low spin (LS) complexes, or tune the SCO properties (such as transition hysteresis or transition temperature) in complexes with SCO. Ligands were divided into three different types according to their spacers: a ligand with an aromatic spacer (L1M), ligands with aliphatic spacer (L2M, L3M) and a ligand with no spacer (L4M). The difference between their structures helped us to better understand the coordination chemistry of the corresponding complexes. The nickel(II) complexes formed provided useful background information on the coordination chemistry of iron(II), such as the crystal field stabilization energy (10Dq) value. An approximation of 10Dq value of iron(II) was calculated based on the 10Dq value of analogous nickel(II) complexes using an empirical rule, to provide a prediction of SCO property. / Thesis (Master, Chemistry) -- Queen's University, 2013-09-20 10:34:02.756

The rational design of ligand architectures that enables the development of well-defined metallic constructs has long been recognized as an avenue toward controlling and/or tuning the properties of the corresponding material. To date, one of the most widely studied ligand systems is 2,2’;6’,2”-terpyridine, whose tridentate chelating environment allows for coordination to a variety of metal ions with a wide range of geometries. The development of a terpy-like framework which incorporates a boratriazine moiety into the central ring has been recently reported by the Brusso group, namely 2,2-difluoro-4,6-bis(2-pyridyl)-1,3-dihydro-1,3,5,2-triazaborinine (Py2F2BTA) and 2,2-difluoro-4,6-bis(2-4,6-pyrimidinyl)-1,3-dihydro-1,3,5,2-triazaborinine (Pm2F2BTA). These compounds constitute unfused analogues to the extensively studied boron dipyrromethene (bodipy) family of luminophores, which are known for their high thermal resistance, chemical robustness, low photodegradation, and interesting photophysical signatures. While numerous bodipy derivatives have been studied, metal coordination with these compounds remains an intricate property to explore. Thus, the work presented herein represents the first investigations into the coordination chemistry of these novel ligand frameworks. Chapter one serves as an introduction to coordination chemistry, exploring important concepts as they relate to the field; the origin of our boratriazine based ligands is also explored within this chapter. Chapter two aims to describe trends in coordination and reactivity of these ligands with iron and cobalt metal sources of different oxidation states. The third and fourth chapter focuses on the targeted use of azide and thiocyanate ligands, respectively, to promote interesting magnetic interactions in related complexes. In the fifth chapter, luminescent metal complexes synthesized through the use of d10 metals are described. Conclusions and future outlooks are then presented in the final section, chapter six.

The work presented herein describes efforts to synthesize and characterize new types of cyanide-bridged molecular materials encompassing both discrete clusters and extended solids. This investigation focused on the incorporation of anisotropic 4d and 5d transition metal ion building blocks into such materials. In this vein, systematic studies on the magnetic properties of families of these cyano-bridges species were conducted and these new materials represent a new addition to the field of cyanide chemistry incorporating for the first time the hexacyanometallates of [Ru(CN)6]3- and [Os(CN)6]3- into discrete molecules and extended networks. These compounds will serve as models for new theoretical studies in understanding the role of magnetic exchange interactions, both isotropic and anisotropic, in the study of nanomagnetic materials. Results were obtained from using the well known octacyanometallates of MoV and WV as building blocks for the synthesis and the magnetic investigation of both trigonal bipyramidal and pentadecanuclear clusters including the discovery of a new SMM. By expanding the research to previously unused hexacyanometallates, the synthesis and characterization of the first known examples of clusters based on hexacyanoosmate(III) and hexacyanoruthenate(III) building blocks and their use in preparing new theoretical models of magnetic species. A novel pair of clusters is further detailed in the study of the trigonal bipyramidal clusters of [Fe(tmphen)2]3[Os(CN)6]2 and [Fe(tmphen)2]3[Ru(CN)6]2 and an in depth study of the CTIST behavior of these clusters using Mossbauer spectroscopy, variable temperature crystallography, epr, and variable temperature IR measurements. Finally, this work discusses new magnetic Prussian Blue analogs prepared from the hexacyanoosmate(III) and hexacyanoruthenate(III) anions with a comparison to the trigonal bipyramidal clusters presented based on these hexacyanoosmate(III) and hexacyanoruthenate(III) building blocks.

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Since only one example of an asymmetric synthesis which involved an intermediate containing an optically active ligand has been reported, two questions immediately arise: "Is this type of asymmetric synthesis an isolated example, or is it a stepping stone toward a generalized trend for Co (III) which may be extended to include levo rotatory, as well as dextro rotatory molecules?" In addition, asymmetric synthesis affords a new avenue for synthesizing resolved neutral complexes.

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