| Description |
Emphasis I Magnetic materials form the foundation for much of our current technology with uses spanning through a wide variety of industries including automotive, energy generation, and electronics, with applications in data storage devices, radios, and televisions. Prussian blue analogs (PBAs) are of special interest as candidates for new magnetic materials. Since its initial discovery, research into Prussian blue and its analogs has grown substantially and continues to grow steadily with well over 200 scientific publications reported annually. To study the effect of cation size in Prussian blue related magnets, and to identify new magnetic materials and structural motifs, we investigated NEt3Me+ and NEt2Me2+ to target A2MnII[MnII(CN)6] (A = NEt3Me, NEt2Me2), leading to a cubic, 3-D extended network structure of A2MnII5(CN)12. The work described within details the optimization of the synthesis of vanadium-chromium based PBAs, to minimize the further oxidation of the vanadium sites. A series of VII-CrIII PBAs were investigated to isolate different synthetic and environmental variables, which led to the development of an alternative synthesis route through pH control during the synthesis. This was utilized to improve the Tc and subsequently minimize oxidation of the vanadium sites. Emphasis II Organic chemistry has been exceptionally well served by this two-electron, two-center (2e-/2c) bonding description and the concept of resonance. However, D2h eclipsed π-[TCNE]22- (TCNE = tetracyanoethylene) represent an unusual class of organic compounds that possess exceptionally long multicenter C-C bonding interactions with 2e-/4c C-C MO bonding description. To date there are ~30 structural determinations of the eclipsed, D2h π-[TCNE]22- dimer with cations. The work described within details an in-depth investigation into the discovery and characterization of a π-[TCNE]22- dimer with a new bonding motif. Reaction of [NMe4]CN with TCNE yielded [NMe4]2[TCNE]2, which possesses the π-[TCNE]22- dimer with two interacting [TCNE]•- fragments in a previously unknown, noneclipsed, C2 conformation. This interaction forms a 3.039(3) Å long 2e-/6c, unusual bonding motif between the central carbon atoms in the [TCNE]•- fragments. Further characterization of these materials including temperature dependent solid state phase transitions and liquid phase equilibrium properties are described and the physical and thermodynamic properties are discussed. |
