Redox Active Compounds & Non-innocent Ligands: Synthesis, Structure, Electrochemistry, EPR Spectroelectrochemistry

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The development of new materials at the molecular level represents the next great advance in technology beyond the miniaturized solid-state devices that drive current technology. Devices that could operate at the molecular level (that is, on the picometer scale) offer a thousand-fold increase in storage density over the smallest integrated circuits available today. The most spectacular advances can be expected in development of sensors that monitor a myriad of processes with great selectivity. Achieving these goals will require the skills of many, but must include major contributions by chemists who both produce new kinds of molecules and gain understanding of properties: colour, physical characteristics, electric field susceptibility, magnetic states, etc.***My research program contributes to this goal by studying the energetics and mechanisms of adding and removing electrons from materials that contain new combinations of elements. The work described herein has two major foci: (i) advances in chemical synthesis of targeted species and (ii) detailed investigations of the consequences of adding and/or removing electrons from them. These new materials contain distinct components, typically `donors' and `acceptors'. One project will prepare carefully designed modifications to a series of donors based on a Group V element, relating the designed-in structures to the propensity for electron transfer. Another will examine the same for a more recent class of donors employing divalent carbon. In a third project, such donors will be examined along with acceptors from Group III elements, which have demonstrated ability to accelerate the addition or removal of dihydrogen. Here electron transfer can probe the driving forces for these transformations. I also propose to perform similar analyses on a class of electron-delocalized Group V and VI element compounds as donors with metallic acceptors in which the degree of electron transfer is not directly quantifiable. The electrical response of such `non-innocent' entities is an indicator of their true electronic state. Furthermore, the interaction of these entities with a unique chromium compound is expected to be able to function as an electric-field-dependent switch, turning activity on with the application of an electrical potential.***I employ inert-atmosphere chambers for synthesis and measurement. Molecular structures are determined most importantly by single-crystal X-ray diffraction methods. Electrical work employs special circuitry capable of varying the applied voltage in a highly controlled manner and measuring very small currents with high precision. Characterization of species at the circuit/chemistry interface involves probing with visible/ultraviolet light and especially electron paramagnetic resonance spectroscopy. All the required major instruments to perform this work are in place.